Angiokeratoma corporis diffusum (Fabry disease) is an X-linked inherited disorder caused by a deficiency of the lysosomal enzyme alpha-galactosidase. This inborn error of metabolism results in unremitting deposition of neural glycosphingolipids in the lysosomes of the vascular endothelium; in fibroblasts; and in pericytes of the dermis, heart, kidneys, and autonomic nervous system. The Fabry disease gene is now known as the GLA gene, which stands for alpha-galactosidase. More than 370 GLA gene mutations have been cloned, all with a cytogenetic location of Xq22, located between base pairs 100,539,452 and 100,549,606.[1]
Beta-mannosidosis, a lysosomal enzyme disorder (which also results in mental retardation, hearing loss, and renal failure); fucosidosis; sialidosis; galactosialidosis; aspartyl-glycosaminuria; GM1 gangliosidosis; and Kanzaki disease can also be causes of angiokeratoma corporis diffusum.[2]
Additionally, several patients without detectable abnormalities have been reported.
Nucleoside sequencing of the entire GLA gene has enabled theoretical treatment using recombinant technology.
A defect in the activity of alpha-galactosidase, a lysosomal enzyme, results in the insidious storage of 2 neutral glycosphingolipids: trihexosylceramide (galactosylgalactosylglucosylceramide) and digalactosylceramide (galabiosylceramide). These glycosphingolipids accumulate in many different types of cells. The most affected are the vascular endothelium and smooth muscle cells. Deposition of glycosphingolipids can be attributed to both endogenous production and diffusion of material from the circulation. As a result of the lack of this lysosomal enzyme that breaks down the glycolipid, persons with Fabry disease have 3-10 times the normal amount in their serum.
Larralde et al[3] have extensively explained the mechanism behind Fabry disease. The enzymatic defect in Fabry disease results in the accumulation of uncleaved glycosphingolipids in many human cell types. Particular types consist of endothelial cells, blood vessel cells, pericytes, vascular smooth muscle cells, renal epithelial cells, myocardial cells, skin structure cells, neuronal cells, and corneal cells.
Important mouse model work involving cardiomyopathy and enzyme replacement continues to be done.[4]
Persons with Fabry disease who have type AB or B blood also accumulate blood group B glycosphingolipids (those with alpha-galactosyl-terminated residues) and can have more severe Fabry disease (related to greater body substrate mass) than patients with blood group A. This is because these blood groups have 2 additional terminal alpha-galactosyl moieties.
Specifically, deposits in lysosomes of endothelial, perithelial, and smooth muscle cells of blood vessels cause swelling into the hollow bore of the blood vessel. In so doing, the vessels are narrowed and reactively expand, which leads to ischemia and infarction. This occurs, to a greater or lesser extent, in all affected cells, underlying the protean manifestations of Fabry disease.
In 2004, Larralde et al[3] report that most families have "private" mutations (ie, mutations found only in that particular family). Fabry disease is transmitted in an X-linked recessive pattern. The gene is located at band Xq22. Similar to other entities with this inheritance pattern, hemizygous males are most severely affected. The female carrier of this disease has diminished levels of alpha-galactosidase, which is enough to cause some symptoms but also to be spared the full clinical manifestations. Deficient alpha-galactosidase A activity can be present in the plasma in persons who do not have the full manifestations of Fabry disease. The deficiency must be extensive for full effects to manifest.
Molho-Pessach et al,[5] in 2007, reported a 36-year-old Arab woman with beta-mannosidosis who presented with mental retardation and multiple angiokeratomas with a novel null mutation involving a G→A transition in exon 6 at nucleotide position c.693, resulting in the formation of a stop codon (W231X).
Researchers found increased serum levels of vascular endothelial growth factor-A (VEGF-A), an endothelial cell mitogen, in 35 patients with angiokeratoma corporis diffusum (Fabry disease) versus matched controls, suggesting VEGF-A might be involved with vascular damage in angiokeratoma corporis diffusum (Fabry disease); however, additional research is needed to clarify the significance of this finding.[6]
Angiokeratoma corporis diffusum (Fabry disease) is rare; the estimated incidence is 1 case per 40,000 population. Others believe this prevalence is an overestimation. According to Larralde et al,[3] inheritance of the abnormal gene among whites (resulting in a hemizygous boy or a heterozygous girl) has been estimated to occur once in every 117,000 live births.
International
Most occurrences of angiokeratoma corporis diffusum (Fabry disease) are in whites; however, Fabry disease has been reported to occur in black persons, Latin Americans, Native Americans, Egyptians, and Asians.
Race
While angiokeratoma corporis diffusum (Fabry disease) is most common in whites, it has been reported in black persons, Latin Americans, Native Americans, Egyptians, and Asians.
Sex
Because angiokeratoma corporis diffusum (Fabry disease) is an X-linked recessive disease, only men are fully afflicted. Heterozygous women, in addition to transmitting the condition, may develop symptoms.
Age
In males, signs and symptoms of angiokeratoma corporis diffusum (Fabry disease) begin in late childhood or adolescence. By age 20-29 years, most affected men experience the full brunt of the disease. Heterozygous women first note symptoms by age 20 years to early 30 years. Möhrenschlager et al[7] report that the Anderson-Fabry disease register shows the median cumulative survival of hemizygous men with Fabry disease is 50 years, compared with 70 years for females. This means that men live approximately 20 years less than unaffected men and that women live 15 years less than unaffected women. Some men, however, even without enzyme replacement, live to their 70s.
Few afflicted men live to be older than 50 years. A male cardiac variant exists in which patients have enough alpha-galactosidase to stave off the renal, neurologic, and skin changes typical of Fabry disease. Patients develop cardiac manifestations, especially cardiomyopathy.
Before the advent of enzyme replacement therapy, renal failure secondary to uremia and hypertension was the major cause of death for men with angiokeratoma corporis diffusum (Fabry disease) aged 30-39 years, followed by congestive heart failure and cerebrovascular accidents. Currently, mortality due to renal pathology seems to be decreasing, leaving cardiac issues as an increasing cause of morbidity and mortality among patients with Fabry disease.[8]
Heterozygous women have a longer lifespan with the disease because if they develop renal and cardiac symptoms, they do so later in life. Heterozygous females develop angiokeratomas and cataracts and experience a milder clinical course. Some patients may have more serious involvement; however, lifespan is longer for women than for men diagnosed with this disease.
A variety of clinical findings occur in female carriers. The scope is vast and ranges from asymptomatic carriers to carriers with fully expressed Fabry disease. Asymptomatic corneal dystrophy occurs in approximately 70% of carriers. This is an indication of the carrier state. Approximately 30% of female carries have angiokeratomas, with less than 10% having paresthesias. A 2004 study by Larralde et al[3] of obligate female carriers found significant disease manifestations in 20 of 60 women. Another study performed on 20 carriers of Fabry disease showed that each woman had some symptom of Fabry disease, with a wide scope of manifestations. Larralde et al[3] concluded that Fabry disease might be designated a storage disease transmitted as an X-linked–dominant, not X-linked–recessive, disease.
Hormonal function and fertility rates are normal in both male and female Anderson-Fabry patients compared with controls.
Genetic counseling is urged. Both affected men and heterozygous women can transmit the gene. Sons of affected men are free of the gene, but daughters can pass the gene to future generations. In the offspring of heterozygous women, 50% of male children may have the disease and 50% of female children may become carriers.
Angiokeratoma corporis diffusum (Fabry disease) is variable in its clinical symptoms and, as a result, can be a challenge to define if it does not manifest in classic fashion or in a person whose family is not known to have Fabry disease. The classic presentation of Fabry disease is a male with initial manifestations occurring in childhood or adolescence. The initial findings are intermittent or chronic paresthesias and episodes of severe acral and/or GI distress (Fabry crisis), heat intolerance, hypohidrosis or anhidrosis, and generalized angiokeratomas.
Angiokeratoma corporis diffusum (Fabry disease) can be confused with more common diseases, delaying its diagnosis. Presentation involves musculoskeletal manifestations. Extremity pain, past or present, is typical. Early and progressively severe osteoporosis manifests.Family history, musculoskeletal disease, and osteoporosis can prompt alpha-galactosidase assays, which define the diagnosis of Fabry disease in males, whereas genetic testing is used in females.[9]
If the diagnosis is missed, it will, in almost all cases, be made when a patient presents with (1) end-stage kidney failure or (2) cardiac or cerebrovascular pathology with early mortality. If the disease is milder (intermediate forms), it may not be diagnosed until late adulthood.
Some variants of Fabry disease only have renal and/or cardiac pathology and no angiokeratomas. A physician can establish that a patient has Fabry disease by searching for low activity of alpha-galactosyl A in plasma, leukocytes, cultured skin fibroblasts, or dried blood spots on filter paper.[3] Because of the Lyon effect, enzymatic detection of carriers can be misleading; thus, specific genetic analysis can be helpful in making the diagnosis.
In its typical form, Fabry disease starts in early childhood and manifests with constant acral paresthesia (acroparesthesia, ie, chronic burning, neuropathic tingling, or unmitigated acral discomfort). Intermittent Fabry crisis is the term for incapacitating sharp pain lasting minutes to days. This can occur in children, but it often stops occurring in adulthood. Crises can be triggered by any kind of stress, including disease, extremes in temperature, exercise, or emotional trauma. In addition to pain, a crisis can also manifest with fatigue, low-grade fever, and joint pain.[3]
The Fabry Registry[10] published the baseline demographic and clinical characteristics of the first 1765 patients enrolled in the Fabry Registry. Of these patients, 54% are males (16% aged < 20 y) and 46% are females (13% aged < 20 y). The median ages at symptom onset and at diagnosis are 9 and 23 years, respectively, for males and 13 and 32 years, respectively, for females. Frequent presenting symptoms in males include neurological discomfort and pathology (62%), skin signs (31%), gastroenterological signs (19%), unspecified renal pathology (17%), and ophthalmological pathology (11%). Frequent presenting symptoms in females include neurological pain (41%), gastroenterological symptoms (13%), ophthalmological symptoms (12%), and skin eruptions (12%).
In men and women with Fabry disease reporting renal progression, the median age at occurrence was 38 years for both men and women. In men and women with Fabry disease reporting an onset of cerebrovascular and cardiovascular events, the median age at occurrence was 43 and 47 years, respectively, for females, and 38 and 41 years, respectively, for males.
Recurrent fevers and vague pain in the hands and feet, resulting in periodically incapacitating pain in the fingers, toes, and occasionally the entire extremity, usually precede physical signs of Fabry disease. Typically, fever, heat, cold, and exertion trigger pain. Paroxysmal vertigo has occurred as an initial manifestation of Fabry disease, which may initially help to establish the diagnosis.
In 2007, Moeller and Jensen[11] noted that females with Fabry disease who present with pain and neurological symptoms are often not appropriately assessed and are misdiagnosed. This is likely because many physicians assume that Fabry disease's X-linked pattern of inheritance means it cannot occur in women.
As stated, the second type of pain is a nagging, chronic, constant discomfort in the hands and feet, characterized by burning tingling paresthesias.
Some patients with Fabry disease manifest with chronic exercise-induced pain, fasciculations, and cramps of the feet and legs. This can affect other members of their families.[12]
Subsequently, angiokeratomas develop, which are the typical skin lesions for which the disease is named. Angiokeratomas usually manifest after puberty and increase in number with age; they can become generalized and involve the mucosa. Angiokeratomas occur as a result of lysosomal storage of Gb3 in cutaneous endothelial cells. This results in impairment of capillary wall integrity and the development of secondary ectasias.
Atypical presentations can occur. In 2005, Choudhury et al[13] reported an 11-year-old boy with Fabry disease who had a 6-year history of widespread petechia, rare papules with an overlying crust, and acral paresthesias of the hands and feet.
Not every case of angiokeratoma corporis diffusum is due to Fabry disease. An idiopathic or cutaneous variant of angiokeratoma corporis diffusum has been described as a discrete clinical category of disease occurring only in the skin in persons with no metabolic disease or lysosomal defect.
Ocular changes may be detected during the disease course. Although ocular involvement may be extensive (affecting the lens, cornea, conjunctiva, and retina), visual impairment is unusual. The fact that Fabry disease does not compromise ocular acuity is notable. It is sometimes a useful finding that helps diagnose Fabry disease. Fabry disease is commonly associated with a corneal opacity that can only be noted with slitlamp biomicroscopy. This corneal opacity shows a whorled pattern. Persons with Fabry disease sometimes manifest anterior capsular deposits in the lens or granular spokelike deposits on the posterior lens, termed Fabry cataract.[3]
Patients may develop chronic edema of the feet before true renal or cardiac dysfunction.
A history of heat intolerance secondary to hypohidrosis is often noted.
With the relentless progression of the disease, cardiac infiltration can result in angina, myocardial infarction, mitral valve prolapse, congestive heart failure, hypertension, mitral insufficiency, and left ventricular hypertrophy. Other cardiac findings may include angina pectoris, aortic outflow abnormalities, arrhythmia, coronary artery disease, myocardial infarction, myocardial ischemia, ECG abnormalities, valvular lesions, varicose veins, and altered vasomotion.
Similarly, glycolipid deposits in the CNS result in paresis, seizures, hemiplegia, labyrinthine disorders, aphasia, tremor, sensory disturbances, and loss of consciousness.
Renal pathology is one of the hallmarks of Fabry disease and is the most frequent cause of death, usually when patients are aged 30-50 years. Polyuria due to concentration defects can be among the first manifestations of kidney malfunction but, in many cases, does not prompt testing that leads to a diagnosis.[3] As persons with Fabry disease approach age 20 years, proteinuria increases as the patient ages. Polarization microscopy of the sediment of urine demonstrates birefringent lipid globules (ie, renal tubular epithelial cells or cell fragments with lipid inclusions) with the characteristic Maltese cross configuration. Birefringent inclusions in the urinary sediment (ie, fat-laden epithelial cells or mulberry cells) may be noted. While protein, red blood cells, casts, desquamated urinary tract cells, and the characteristic Maltese crosses of lipid globules can be seen in childhood, the kidneys do not exhibit signs of deterioration until the patient is older. By middle age, azotemia and progressive proteinuria reflect deteriorating renal function. Uremia usually ensues and heralds end-stage renal disease.
When the GI system is affected, a patient with Fabry disease has a history of intermittent nonbloody diarrhea and proctocolitis.
Rheumatologically, patients may have arthritis of the distal interphalangeal joints with some loss of motion and limitation of movement of the temporomandibular joints.
Angiokeratoma corporis diffusum is linked to beta-mannosidosis. Mental retardation, hearing loss, and renal failure are also linked to angiokeratoma corporis diffusum. In one case, the activity level of beta-mannosidase in the patient's plasma was 2% of the normal range, while the level in the patient's mother was 40%.[2]
Persons with Fabry disease have a high rate of subclinical hypothyroidism.
Other nervous system findings of Fabry disease include headache, hearing loss, psychologic/psychiatric disease, tinnitus, tremors, vertigo, and aphasia.
Angiokeratoma corporis diffusum (Fabry disease) was reported in a patient with Hodgkin lymphoma, possibly suggesting it might be a new, albeit rare, paraneoplastic skin finding.[14]
Depression is common in adults with Fabry disease and is an underdiagnosed problem.[15]
Dominguez et al,[16] in 2007, found that restless legs syndrome is common in Fabry disease patients and is associated with neuropathic pain.
Physical findings involve the skin, heart, lungs, extremities, eyes, and neurologic system.
Skin findings
The hallmark of the disease, angiokeratoma, is a lightly verrucous, deep-red to blue-black papule varying in size from punctate to 0.5 cm. These are a type of capillary malformation.[17] See the images below.
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Angiokeratomas are commonly observed as dense cluster of lesions on the flank and private areas.
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Angiokeratoma is the small punctate reddish-to-bluish angiectases on the umbilicus.
Early, small lesions may not be hyperkeratotic; however, as lesions age and enlarge, their surfaces become somewhat crusty. Discrete verrucous overgrowth can occur.
Great variation in lesion size is evident, making patients appear as if they are "peppered with buckshot."
The papules of Fabry disease are symmetric and do not blanch with pressure (diascopy negative).
Angiokeratomas can appear almost anywhere; however, typically they spare the face, scalp, and ears. Lesions tend to concentrate between the umbilicus and the knees, with a predilection for the scrotum, penis, lower back, thighs, hips, buttocks, and lips. Some authors have stated that the angiokeratomas occur in the "bathing trunk" area.
Patients with Fabry disease can have scant body hair.
Other skin findings include varicose veins, stasis-related edema, lymphedema of the arms and legs, and edematous upper eyelids.
Hypohidrosis[18] and Raynaud phenomenon[19] can be early signs of the existence of Fabry disease.
Cardiac findings
Fabry disease is associated with a high prevalence of cardiac morbidity. In 2007, Linhart et al[20] noted that while Fabry disease has well-described associations with microvascular disease, deficiency of GLA is associated with premature macrovascular events such as stroke and, likely, heart attack.
Sadick and Thomas[21] studied the heart pathology in 12 patients and reported that 5 had cardiovascular symptoms, 9 had left ventricular hypertrophy on ECG tracings, 1 had a short PR interval, 3 had epicardial coronary disease, 4 had a rat-tail appearance on left-sided ventriculogram images, and 6 were assessment by myocardial biopsy, which demonstrated extensive vacuolation of the myocytes on light microscopy and concentric, myelinoid lamellar cytoplasmic inclusion bodies on electron microscopy.
Alterations in parameters as reported by Sadick and Thomas[21] were (1) traditional parameters of diastolic function, including peak E velocity, peak A velocity, and deceleration time, were no different between Fabry disease patients and normal controls; (2) isovolumic relaxation time was significantly prolonged in Fabry disease patients; (3) pulmonary venous atrial reversal duration exceeded that of mitral A wave duration in patients with Fabry disease; and (4) septal E' velocity with Doppler tissue imaging was much lower in Fabry disease patients compared with normal controls.
Murmurs associated with mitral regurgitation and stenosis may be heard.
Left ventricular hypertrophy is apparent in patients with more advanced disease.
Signs of congestive heart failure and hypertension are noted.
Pulmonary findings
Pulmonary findings include wheezing respirations and dyspnea, which are frequent. Lymphedema and varicose veins are also common. Additionally, hearing loss can be a familial part of Fabry disease.[22] Vestibular and auditory deficits in Fabry disease patients are often responsive to enzyme replacement therapy.[23]
Ocular findings
Ocular changes may be specific, and the diagnosis may be made on the basis of ophthalmologic examination findings. Corneal changes vary from diffuse haziness to corneal opacities characterized by whorled streaks extending from a central point to the periphery of the cornea. This change is identical to chloroquine or amiodarone toxicity. Posterior capsular cataracts with whitish spokelike deposits of granular material may be seen. This type of cataract may be the first sign of ocular involvement and is so characteristic that it has been dubbed the Fabry cataract. Occasionally, aneurysmal dilatation of thin-walled venules is seen on the bulbar conjunctiva. Mild-to-marked tortuosity and angulation of the retinal vessels occur. Conjunctival vascular tortuosity may be the most common eye finding associated with Fabry disease. In a study of 25 patients with Fabry disease, Wasik et al found more bushy capillaries and clusters of vessels in persons with Fabry disease (72%) versus those without disease (10%). Seventeen of the patients were males who had not used enzyme replacement treatment.[24]
See the image below.
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Corneal verticillata, commonly seen in patients with Fabry disease, detectable by slit lamp examination
Neurologic findings
Neurologic findings include multifocal small vessel involvement, which may result in hemiplegia, hemianesthesia, balance disorders, and personality changes. Chiari type I malformation has been reported in some patients with Fabry disease and should be sought if apposite MRI screening is performed. The role of general screening for Chiari type I malformation is not clear. Chronic meningitis and thalamic involvement has been described in a woman with Fabry disease.[25]
Bone findings
Osteopenia and osteoporosis have been linked to Fabry disease.[26] Bilateral femoral head and distal tibial osteonecrosis have also been linked to Fabry disease. Osteopenia is common in Fabry disease patients.[27]
Gastrointestinal findings
Gastrointestinal symptoms were found to be common patients with Fabry disease, as reported by Hoffmann et al in 2008. Symptoms were similar to inflammatory bowel disease; these symptoms improved with enzyme replacement therapy.[28]
A defect in the activity of alpha-galactosidase, a lysosomal enzyme, results in the insidious storage of 2 neutral glycosphingolipids: trihexosylceramide (galactosylgalactosylglucosylceramide) and digalactosylceramide (galabiosylceramide). Angiokeratoma corporis diffusum is inherited in an X-linked recessive pattern.
Renal: Azotemia and progressive proteinuria can lead to frank uremia.
Neurologic: Pain from Fabry disease can be debilitating. Other neurologic problems include paresis, seizures, hemiplegia, labyrinthine disorders, aphasia, tremor, sensory disturbances, and loss of consciousness.
Cardiac: Fatal cardiac complications can result from cardiac hypertrophy, ventricular tachycardias, and dilated cardiomyopathy. A number of other cardiac complications may occur, including mitral regurgitation, mitral stenosis, left ventricular hypertrophy, congestive heart failure, and hypertension. Arrhythmias occur commonly in older patients with Fabry disease. Pacemaker implantation is often required, especially because of the possibility of sudden cardiac death associated with Fabry disease.
Other: Wheezing and dyspnea occur as small vessels in the lungs are affected. Fairly marked lymphedema and varicose veins result from the disease's effect on small blood vessels of the legs.
Serum, leukocytes, tears, skin biopsy samples, and cell cultures demonstrate alpha-galactosidase deficiency. These tests are the most definitive means of diagnosis.
Papaxanthos-Roche et al[30] noted that azoospermia can be a feature of Fabry disease.
Holzl et al reported in 2010 on a fast and simple (yet sensitive) test to identify enzyme deficiencies in patients with angiokeratoma corporis diffusum Fabry disease).[31]
Novel Gb(3) isoforms can be found in patients with Fabry disease.[32]
Pereira et al found the lysosome-associated membrane proteins (LAMP) 1 and 2 are normal in normal controls and normalize with treatment with alpha-galactosidase.[33] This helps to measure the effective of enzyme replacement therapy.
Using a mouse model, Shu et al found that 3-nitrotyrosine can function as a marker for Fabry disease–related vasculopathy.[34]
A variety of imaging studies can be used to evaluate Fabry disease. These include cardiac, body, and brain imaging tests.
Neurological
In a group of young Fabry disease patients with normal MRI findings, a significant increment of greater than 12% in apparent diffusion coefficient values in the corona radiata occurred compared with age-matched controls. The difference might demonstrate increased interstitial water in tissue after the Starling equilibrium under raised cerebral blood flow. This increase water content has been previously defined as a manifestation of Fabry disease. Thus, increased apparent diffusion coefficient values might occur before conventional MRI changes in persons with Fabry disease. Increased apparent diffusion coefficient values seem to be a sensitive marker of disease progression and the healing effect of enzymatic replacement therapy.[35]
Cardiac
Echocardiography can disclose left ventricular hypertrophy and systolic anterior motion of the mitral leaflets. Cardiac catheterization can show marked gradient loss in the left ventricular peak systolic outflow gradient, which indicates the presence of left ventricular outflow obstruction. Cardiac MRI might play a role in evaluating the effectiveness of enzyme therapy for Fabry disease.[36]
Slit-lamp examination of the eyes of patient with Fabry disease can reveal a whorl-like keratopathy.[37] Thus, ophthalmic examination can be useful in defining Fabry disease.
A variety of neurological tests can be done to detect small-fiber neuropathy in Fabry disease and other small-fiber diseases that involve neuropathy.[38]
The characteristic angiokeratoma of Fabry disease is found diffusely and is not limited to the scrotum as it is in Fordyce angiokeratoma. Mibelli angiokeratoma is observed primarily on the dorsum of the hands and feet. Angiokeratoma circumscriptum is a rare type of angiokeratoma with a unilateral distribution of discrete papules and nodules localized to a small area of the legs or trunk.
Slit-lamp ophthalmologic examination demonstrates characteristic corneal opacity. Also, look for the unique spokelike cataracts in the posterior capsule.
Histology shows numerous, dilated, thin-walled, endothelial-lined, blood-engorged capillaries in the papillary dermis, with an overlying hyperkeratotic epidermis. Careful inspection may reveal cytoplasmic vacuoles containing lipid in the endothelial cells, fibroblasts, and pericytes. However, in most patients, histologic findings essentially are identical to those of other angiokeratomas.
Endomyocardial biopsy findings of the heart can demonstrate sarcoplasmic vacuolization of cardiac muscle cells under light microscopy and lamellated zebra bodies in the cytoplasm under electron microscopy.
Electromicroscopy investigation can show stromal cells in hemizygous tissue and endothelial and smooth muscle cells in heterozygous tissue; cells contain membrane-bound inclusions with a lamellar structure (ie, inclusion bodies with a zebralike appearance).
As a multisystemic disease, angiokeratoma corporis diffusum requires treatment by a number of specialists. Treatment is intended to extend the lifespan of affected patients and make their lives more comfortable, especially in light of the often excruciating pain they experience. Significant clinical improvement and enhancement of quality of life have been achieved with enzyme replacement therapy (ERT), in particular at the early stages of Fabry disease, with positive benefits for the cardiac and renal systems and a decrease in pain.
Early detection of Fabry disease has made extending the lifespan and improving the quality of life possible for these patients. The administration of recombinant human alpha-galactosidase or agalsidase beta replacement therapy can reverse and delay cardiac, renal, and neural damage to patients with Fabry disease. It is not clear which enzyme therapy is superior and both therapies are helpful at enhancing health.
Future treatments of Fabry disease that seem promising include (1) substrate deprivation based on the inhibition of an earlier step in the synthesis of the accumulating glycosphingolipid and (2) gene therapy.
Note the following treatments broken down by specialty:
Dermatology: Carbon dioxide laser treatment can improve cosmetic appearance by removing angiokeratomas from the skin. Variable pulse width 532-nm Nd:YAG laser therapy, 578-nm copper vapor laser therapy, and flashlamp-pumped dye laser therapy can also be used to treat angiokeratomas. Hyperhidrosis can be treated with topical and systemic antiperspirant agents. Hypohidrosis or anhidrosis can be treated with moisturizers and topical applications of artificial lacrimal fluid and saliva.
Nephrology: Renal insufficiency, the most common cause of mortality, can be treated with hemodialysis or kidney transplantation. Renal transplantation may benefit patients because it supplies a source of the missing enzyme alpha-galactosidase A.
Neurology: Two antiseizure medications, diphenylhydantoin and carbamazepine, are the most helpful in alleviating the debilitating pain of neurologic involvement.
Pulmonology: Obstructive lung disease is a problem late in the disease process. Discourage patients from smoking.
Gene therapy: In recent years, nucleoside sequencing of the entire alpha-galactosidase A gene has enabled theoretical treatment using recombinant technology.
Replacement therapy: Occasionally, infusions of plasma or partially purified enzyme from healthy donors have produced promising results.
Politei suggested that statins might be helpful in the treatment of Fabry disease to help prevent stroke, owing to neuroprotective properties or pleiotropic effects.[39]
Cardiology: Imbriaco et al reported that twice-monthly continuous treatment with agalsidase beta at 1 mg/kg every 2 weeks significantly reduced left ventricular hypertrophy, improving overall heart performance and decreasing clinical symptoms in Fabry disease.[40]
Kidney transplantation often is beneficial. Kidney transplantation improves survival. In addition to restoring renal reserve, the transplanted kidney produces a portion of the lacking enzyme alpha-galactosidase.
Consultation with the following specialists may be necessary:
Nephrologist: Kidney failure is responsible for most fatalities associated with angiokeratoma corporis diffusum. A nephrologist can determine when renal dialysis and transplantation are indicated.
Neurologist: Patients describe the pain associated with nerve involvement of Fabry disease as excruciating. In addition, a number of CNS problems are associated with this condition.
Cardiologist: In addition to congestive heart failure and hypertension resulting from renal impairment, frequent primary dysfunction of the heart occurs.
Pulmonologist: As the lung vasculature becomes increasingly affected, obstructive pulmonary disease often develops.
Geneticist: Genetic counseling is helpful in this genetically transmitted disease.
Screening for Fabry disease using analysis of spots of whole blood fails to identify one third of female carriers.[41]
With regard to urinary testing, the Fabry hemizygotes have higher concentrations of the substrate for the deficient enzyme, ceramide trihexoside, lactosylceramide, and ceramide in combination with decreased concentrations of glucosylceramide and sphingomyelin. Ratios of these analytes enhanced distinction between the control and Fabry groups. The Fabry heterozygotes had levels between the Fabry hemizygotes and the control group.[42]
The goals of pharmacotherapy are to reduce morbidity and prevent complications.
Early intervention with enzyme replacement therapy (ERT) with intravenous infusions of recombinant human alpha-galactosidase A consistently and clearly decreases Gb3 levels in the blood plasma and clears vascular endothelial cellular lysosomal inclusions. While effects on other tissue are no so obvious, ERT, when initiated early, seems to prevent cellular damage and disease complications.[43] Certain genetic defects can make enzyme replacement treatment less effective or totally ineffective and can lead to renal failure.[44]
Lidove et al[45] noted that 2 formulations of the enzyme alpha-galactosidase A are used in Europe: agalsidase alpha (produced in a human cell line) and agalsidase beta (produced in Chinese hamster ovary cells). Two different enzyme preparations are made by different companies: agalsidase alpha (Replagal, Shire) and agalsidase beta (Fabrazyme, Genzyme). Lin et al found that patients can be switched form alpha-galactosidase to agalsidase beta with no ill effect after one year follow-up.[46]
Lidove et al,[45] based on a review of 11 trials, reported that these preparations both appear to have clinical efficacy but that further assessments are needed. The trials have not been optimal in design and would benefit from a prospective design and a specific investigation into the effects of ERT in women and on the use of ERT early in the course of Fabry disease to halt organ damage before it starts. Additionally, Kim et al[47] noted that the pulmonary manifestations of Fabry disease respond positively to ERT.
A report from France in 2012[48] studied the use of miglustat hydrochloride, an investigational pharmacological chaperone, given orally at 150 mg every other day in 2 phase 2 studies. Researchers found miglustat hydrochloride increased α-Gal A activity of at the very least 50% in blood, skin, and kidney in 6 of 9 patients. In this study, α-Gal A activity also induced GL-3 reduction in skin, urine, and/or kidney. This is promising drug and is being studied in phase 3 studies.
Clinical Context:
Phenytoin may act in the motor cortex where it may inhibit the spread of seizure activity. Activity of the brainstem centers responsible for the tonic phase of grand mal seizures also may be inhibited.
Individualize dosing; if the dose cannot be divided equally, the larger dose should be taken before retiring for the evening.
Clinical Context:
Agalsidase alfa is a recombinant form of the human enzyme alpha-galactosidase A, levels of which are deficient in persons with Fabry disease. Data from clinical trials show a decrease in GL-3 levels following enzyme replacement, reversal in lipid tissue storage, stabilized or improved renal and cardiac function, and reduced or relief from neuropathic pain. Following enzyme replacement, long-term use of neuropathic pain medication has been reduced.
Agalsidase beta (Fabrazyme) is manufactured by Genzyme Corporation (Cambridge, Mass) and is based on the expression of the human GLA gene in CHO cells.
Agalsidase alfa (Replagal) is manufactured by Transkaryotic Therapies (Cambridge, Mass) and is based on activation of the human GLA gene expression in human (skin) fibroblasts.
Noah S Scheinfeld, JD, MD, FAAD, † Assistant Clinical Professor, Department of Dermatology, Weil Cornell Medical College; Consulting Staff, Department of Dermatology, St Luke's Roosevelt Hospital Center, Beth Israel Medical Center, New York Eye and Ear Infirmary; Assistant Attending Dermatologist, New York Presbyterian Hospital; Assistant Attending Dermatologist, Lenox Hill Hospital, North Shore-LIJ Health System; Private Practice
Disclosure: Nothing to disclose.
Coauthor(s)
Anusuya Mokashi, MD, MS, Resident Physician, Department of Radiology, Staten Island University Hospital
Disclosure: Nothing to disclose.
Specialty Editors
Michael J Wells, MD, FAAD, Dermatologic/Mohs Surgeon, The Surgery Center at Plano Dermatology
Disclosure: Nothing to disclose.
Rosalie Elenitsas, MD, Herman Beerman Professor of Dermatology, University of Pennsylvania School of Medicine; Director, Penn Cutaneous Pathology Services, Department of Dermatology, University of Pennsylvania Health System
Disclosure: Received royalty from Lippincott Williams Wilkins for textbook editor.
Chief Editor
William D James, MD, Paul R Gross Professor of Dermatology, Vice-Chairman, Residency Program Director, Department of Dermatology, University of Pennsylvania School of Medicine
Disclosure: Received income in an amount equal to or greater than $250 from: Elsevier; WebMD.
Additional Contributors
Timothy McCalmont, MD, Director, UCSF Dermatopathology Service, Professor of Clinical Pathology and Dermatology, Departments of Pathology and Dermatology, University of California at San Francisco; Editor-in-Chief, Journal of Cutaneous Pathology
Disclosure: Received consulting fee from Apsara for independent contractor.
Acknowledgements
Arnold R Oppenheim, MD Assistant Professor, Department of Internal Medicine, Division of Dermatology, Eastern Virginia School of Medicine
Arnold R Oppenheim, MD is a member of the following medical societies: American Academy of Dermatology and American Society for Clinical Pathology
Disclosure: Nothing to disclose.
References
U.S. National Library of Medicine, part of the National Institutes of Health,. GLA. Genetics Home Reference. Available at http://ghr.nlm.nih.gov/gene=gla. Accessed: June 21, 2009.
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