127: Fabry Disease Flashcards
What is the incidence of Fabry disease in different populations?
The incidence of Fabry disease is estimated to be between 1:40,000 and 1:170,000 across all ethnic groups. Specific incidences include 1:3200 in Italy and 1:7000 in Japan.
What are the primary causes of Fabry disease?
Fabry disease is caused by a partial or complete deficiency of the lysosomal enzyme α-galactosidase A.
What is the significance of globotriaosylsphingosine levels in Fabry disease?
Elevated levels of globotriaosylsphingosine correlate with the severity of Fabry disease and inhibit the activity of α-galactosidase A.
How does the expression of Fabry disease vary in females?
In females, the expression of Fabry disease can be variable due to the Lyon hypothesis, which states that one X chromosome is inactivated randomly.
What are the characteristics of angiokeratomas in Fabry disease?
Angiokeratomas are a cutaneous hallmark of Fabry disease, present in 70% of males and 39% of females. They are pinpoint lesions, dark red to blue-black, that do not blanch on pressure.
Where are angiokeratomas typically located in males with Fabry disease?
In males, angiokeratomas are typically found in the ‘bathing trunk’ area, including the genitals, buttocks, lower abdomen, umbilicus, groins, inner thighs, and sacrum.
What is the incidence of Fabry disease in the general population?
1 in 40,000 to 1 in 170,000.
What is the genetic basis of Fabry disease?
It is caused by a partial or complete deficiency of the lysosomal enzyme alpha-galactosidase A.
What is the cutaneous hallmark of Fabry disease?
Angiokeratoma.
In which demographic is Fabry disease more prevalent?
It affects all ethnic groups, with a higher incidence in males.
What is the typical age range for the appearance of angiokeratomas in males?
Between ages 5-15 years.
What is the significance of globotriaosylsphingosine in Fabry disease?
Elevated levels correlate with disease severity and inhibit the activity of alpha-galactosidase A.
What is the Lyon hypothesis in relation to Fabry disease?
It explains the variable expression in females due to random inactivation of one X chromosome.
What are the common locations for angiokeratomas in males?
Typically in the bathing trunk area, including genitals, buttocks, and lower abdomen.
What is the life expectancy for individuals with Fabry disease?
20 years in males and 15 years in females.
What types of mutations are associated with the GLA gene in Fabry disease?
More than 600 mutations including missense, nonsense, and single amino acid deletions and insertions.
What histopathological features are observed in Fabry disease?
- Dilated, ectatic capillaries in the papillary dermis
- Thinned epidermis with acanthosis at the edges
- Overlying focal compact orthokeratosis
- Cytoplasmic vacuoles in endothelial, perithelial, perineural, eccrine, and smooth muscle cells filled with glycosphingolipid
- Presence of zebra bodies on electron microscopy.
How do cutaneous vascular lesions relate to disease severity in Fabry disease?
Presence of cutaneous vascular lesions is associated with higher disease severity scores and increased prevalence of major organ involvement.
What facial features are associated with Fabry disease?
‘Pseudoacromegalic’ facial appearance includes periorbital fullness, prominent ear lobes, bushy eyebrows, recessed forehead, and pronounced nasal angle.
What is the significance of lower-limb edema and lymphedema in Fabry disease?
Lower-limb edema and lymphedema are frequently observed and may indicate underlying changes related to glycosphingolipid accumulation.
What are zebra bodies and their significance in Fabry disease?
Zebra bodies are characteristic electron-dense, lamellated, intracytoplasmic vacuolar inclusions seen on electron microscopy.
What is the relationship between cutaneous vascular lesions and disease severity in Fabry disease?
The presence of telangiectases and/or angiokeratomas is associated with higher disease severity scores.
What is the significance of lymphedema in Fabry disease?
Lymphedema is frequently observed and may indicate underlying changes related to glycosphingolipid accumulation.
How do telangiectases present in patients with Fabry disease?
Telangiectases blanch on diascopic pressure, are more common in males, and often occur at sun-exposed sites.
What is the typical age of onset for telangiectases in Fabry disease?
The mean age of onset is 26 years in males and 42 years in females.
What factors contribute to the development of lymphedema in Fabry disease?
Glycosphingolipid accumulation, recurrent edema, and primary abnormalities of the lymphatics.
What diagnostic tools are useful when other tests are inconclusive in Fabry disease?
Electron microscopy and immunoelectron microscopy using anti-Gb3 antibodies.
What systemic complications should be monitored in a male patient with Fabry disease?
Systemic complications to monitor include cerebrovascular, cardiac, and renal involvement.
What is the likely mechanism behind lymphedema and elevated serum VEGF-A levels in Fabry disease?
The lymphedema is likely due to glycosphingolipid accumulation, recurrent edema, or a primary abnormality of the lymphatics.
What dermatologic assessments are predictive of systemic morbidity in Fabry disease?
The presence of cutaneous vascular lesions is associated with higher disease severity scores.
What histopathologic features are characteristic of angiokeratomas?
Histopathologic features of angiokeratomas include dilated, ectatic capillaries in the papillary dermis and variable degrees of overlying focal compact orthohyperkeratosis.
What systemic complications are associated with widespread angiokeratomas?
The presence of widespread angiokeratomas is associated with higher disease severity scores and a higher prevalence of major organ involvement.
What are the common abnormalities of sweating associated with Fabry disease?
Reduced sweating is a classical feature of Fabry disease, affecting 53% of males and 28% of females.
What ocular findings are associated with sensory organ abnormalities in Fabry disease?
Cornea verticillate is characterized by lines radiating from the center of the cornea, occurring in >90% of males and 70% of females.
What gastrointestinal changes are commonly observed in patients with Fabry disease?
Common symptoms include cramping abdominal pain, nausea, diarrhea, and occasionally constipation.
What are the renal manifestations of Fabry disease?
Renal manifestations are seen in >90% of males, including microalbuminuria and hyperfiltration as early features.
What are the cardiac manifestations associated with Fabry disease?
Cardiac manifestations are increasingly recognized as a major cause of death in Fabry disease.
What is hypohidrosis and its prevalence in males and females with Fabry disease?
Hypohidrosis occurs in 53% of males and 28% of females.
What symptoms are associated with heat intolerance in Fabry disease?
Heat intolerance can result in reduced exercise tolerance, nausea, and light-headedness.
What is the Raynaud phenomenon in the context of Fabry disease?
Cold intolerance and the development of pain in the extremities in cold environments is a frequent complaint.
What ocular finding is most common in Fabry disease?
Cornea verticillate, characterized by opacities in the cornea, occurs in >90% of males and 70% of females.
What auditory findings are common in patients with Fabry disease?
Tinnitus and high-frequency sensorineural hearing loss are common, occurring in more than 50% of patients.
What gastrointestinal symptoms are often presenting in Fabry disease?
Cramping abdominal pain, nausea, diarrhea, and occasionally constipation are often the presenting symptoms.
What renal manifestations are seen in males with Fabry disease?
Renal manifestations are seen in >90% of males, including microalbuminuria and hyperfiltration.
What is a common cardiac manifestation in Fabry disease?
Left ventricular hypertrophy is a common presentation.
What triggers acroparesthesias in individuals with Fabry disease?
Triggers include increased body temperature, exercise, and stress.
What is the pathophysiology behind acroparesthesias in Fabry disease?
Acroparesthesias are caused by damage to nerve fibers due to inflammation and substrate accumulation.
What is the likely cause of sudden hearing loss and dizziness in a patient with Fabry disease?
The likely cause is high-frequency sensorineural hearing loss and vestibular dysfunction.
What is the significance of cornea verticillata in Fabry disease?
Cornea verticillata is the most common ocular finding, occurring in >90% of males and 70% of females.
What are the characteristics of the renal variant of Fabry disease?
The renal variant is characterized by decreased but not absent alpha-galactosidase A activity.
What is the underlying cause of heat intolerance in Fabry disease?
Heat intolerance is due to hypohidrosis or anhidrosis.
What is the significance of left ventricular hypertrophy in Fabry disease?
Left ventricular hypertrophy is a common cardiac manifestation caused by substrate deposition.