Fabry Disease — Symptoms, Causes & Treatment | MyMedicPlus

Fabry disease (Anderson-Fabry disease) is a rare, progressive, X-linked lysosomal storage disorder caused by mutations in the GLA gene encoding the lysosomal enzyme alpha-galactosidase A (α-Gal A). Deficient enzyme activity leads to progressive intracellular accumulation of globotriaosylceramide (Gb3/GL-3) and its deacylated derivative globotriaosylsphingosine (lyso-Gb3) in vascular endothelial cells, smooth muscle cells, cardiomyocytes, renal podocytes, tubular cells, and neurons throughout the body. Fabry disease has an estimated prevalence of approximately 1 in 40,000 to 1 in 170,000 in the general population, but screening studies of dialysis populations and young stroke patients suggest it may be underdiagnosed, with prevalence potentially as high as 1 in 3,000–4,000. The classic, severe phenotype occurs predominantly in males (who, as hemizygotes, express no functional α-Gal A) and presents in childhood with neuropathic pain and progresses to cardiac, renal, and cerebrovascular disease causing premature death in the 4th–5th decade without treatment. Female carriers (heterozygotes) express a wide spectrum of disease — from asymptomatic to severe — depending on X-chromosome inactivation patterns; all female carriers should be assessed and monitored. Enzyme replacement therapy (ERT) has transformed the prognosis of Fabry disease since 2001, substantially reducing organ progression when initiated before irreversible damage.

Fabry disease is caused by mutations in the GLA gene located on the X chromosome (Xq22.1), encoding the lysosomal enzyme alpha-galactosidase A. Over 1,000 pathogenic mutations have been identified, including missense mutations (most common), nonsense mutations, splice-site mutations, deletions, insertions, and rearrangements. The G9975 insertion (late-onset variant) and the p.Asn215Ser mutation are associated with late-onset cardiac-variant Fabry disease — presenting with hypertrophic cardiomyopathy in middle-aged men without the classic systemic manifestations. Males with pathogenic mutations (hemizygotes) typically express the full disease spectrum; females are heterozygous carriers who may or may not have significant disease depending on X-chromosome inactivation (lyonisation). The disease follows X-linked inheritance: affected fathers pass the mutant GLA allele to all daughters (obligate carriers) and none of their sons; carrier mothers have a 50% chance of transmitting the mutation to both sons (who would be affected) and daughters (who would be carriers). De novo mutations account for approximately 10–15% of cases, making a negative family history insufficient to exclude the diagnosis. Gb3 accumulation causes endothelial dysfunction, progressive smooth muscle hypertrophy in vessel walls, glomerulosclerosis in podocytes, cardiomyocyte hypertrophy, and neuronal dysfunction in dorsal root ganglia (peripheral neuropathic pain) and autonomic ganglia.

Classic Fabry disease in males presents in childhood (typically ages 5–10 years) with peripheral neuropathic pain — acroparesthesiae (burning or lancinating pain in the palms and soles, triggered by fever, exercise, heat, cold, or emotional stress) from small-fibre neuropathy in dorsal root ganglia — often misdiagnosed for years as juvenile arthritis, Raynaud's disease, or growing pains. Angiokeratomas (small dark-red to black, non-blanching papules) appear on the skin — classically in a 'bathing suit' distribution (umbilicus, genitalia, buttocks, upper thighs) — and are pathognomonic when present. Hypohidrosis (reduced or absent sweating) causes heat intolerance and exercise limitation. Corneal verticillata (whorl-pattern corneal deposits visible only on slit-lamp examination) are present in virtually all affected males and 70% of female carriers — asymptomatic but diagnostically important. Characteristic lenticular opacities (posterior lens capsule) are also common. Progressive organ involvement: renal disease (proteinuria in early adulthood, progressive CKD, end-stage renal disease requiring dialysis by ages 30–40 in classic untreated males); cardiac disease (left ventricular hypertrophy — LVH — from Gb3 deposition in cardiomyocytes; hypertrophic cardiomyopathy; arrhythmias — atrial fibrillation, Brady and tachyarrhythmias; progressive heart failure); cerebrovascular disease (stroke and TIA from vasculopathy — 6-fold increased stroke risk in young patients); gastrointestinal symptoms (nausea, abdominal pain, diarrhoea — from autonomic neuropathy and mucosal infiltration); hearing loss and tinnitus.

Diagnosis is confirmed by measuring alpha-galactosidase A enzyme activity: leukocyte α-Gal A enzyme activity — significantly reduced (typically less than 1–5% of normal) in affected males is diagnostic. Female carriers may have intermediate or even normal enzyme activity due to X-chromosome inactivation — enzyme activity is insufficient for diagnosis in females. GLA gene sequencing is required for all female patients and to identify the specific mutation for family cascade screening. Plasma and urine Gb3 and lyso-Gb3 measurement: markedly elevated lyso-Gb3 (above 2 nM) supports the diagnosis and is a useful biomarker for monitoring treatment response — lyso-Gb3 is more sensitive than Gb3 and does not require direct enzyme measurement. Plasma lyso-Gb3 is elevated even in female carriers with intermediate enzyme activity. Dried blood spot (DBS) cards enable cost-effective newborn screening and opportunistic screening in at-risk populations. Organ assessment at diagnosis includes: echocardiography (LVH, wall thickness — interventricular septum above 12 mm is abnormal); 24-hour ECG Holter monitoring (arrhythmia); brain MRI (white matter lesions, posterior fossa hyperintensities characteristic of Fabry disease, prior stroke); renal function (eGFR, urine albumin-to-creatinine ratio — proteinuria is an early marker of nephropathy); audiology; ophthalmology (slit-lamp corneal verticillata). Annual monitoring (on ERT) includes serum Gb3/lyso-Gb3, eGFR, urine ACR, echocardiogram, ECG, and neurological assessment.

Enzyme replacement therapy (ERT) is the disease-modifying mainstay: intravenous infusions administered every 2 weeks, replacing the deficient α-Gal A enzyme and clearing Gb3 from vascular endothelium, heart, and kidneys. Two licensed ERTs — agalsidase alfa (Replagal — 0.2 mg/kg) and agalsidase beta (Fabrazyme — 1.0 mg/kg) — both effective; head-to-head trials show equivalent clinical outcomes in most analyses. ERT stabilises renal function, reduces LVH progression, and decreases pain events when initiated before advanced organ damage; it is less effective once cirrhosis-equivalent nephrosclerosis or extensive fibrosis has developed — underscoring the importance of early initiation in childhood or early adulthood. Migalastat (Galafold): an oral pharmacological chaperone that stabilises misfolded but functional mutant α-Gal A protein — approved for patients with amenable mutations (approximately 50% of mutations are amenable — confirmed by a standardised cell-based assay); taken every other day; comparable long-term efficacy to ERT in amenable mutations with the advantage of oral administration. Symptomatic management: neuropathic pain — gabapentin (300–3,600 mg/day), pregabalin (150–600 mg/day), carbamazepine, mexiletine, and opioids for breakthrough pain; renal protection — ACE inhibitors/ARBs from the onset of proteinuria (reduce progressive nephropathy); cardiac management — antiarrhythmic therapy, ICD for high-risk arrhythmias, heart failure medications; antiplatelet therapy (aspirin or clopidogrel) and anticoagulation (for AF) for stroke prevention; renal replacement therapy (dialysis or transplantation — Fabry patients have excellent graft outcomes and ERT can continue post-transplant). Gene therapy trials are ongoing.

Progressive renal failure leading to end-stage kidney disease (ESKD) requiring dialysis or transplantation is the principal life-limiting complication in untreated classic Fabry males — occurring in the 4th decade of life on average; even with ERT, renal progression may continue once significant glomerulosclerosis and interstitial fibrosis are established. Hypertrophic cardiomyopathy (HCM) and cardiac arrhythmias: Fabry cardiomyopathy causes progressive left ventricular hypertrophy, diastolic dysfunction, and eventually systolic heart failure; life-threatening arrhythmias (ventricular tachycardia, complete heart block) cause sudden cardiac death — the most common single cause of death in Fabry disease, accounting for 30–40% of mortality; ICD implantation is indicated in high-risk patients. Stroke and TIA: Fabry disease causes a 6 to 12-fold increased risk of stroke in young adults (ages 20–45) from Gb3 deposition in cerebrovascular walls causing vasculopathy, thrombosis, and embolism from cardiac arrhythmias and cardiomyopathy. White matter lesions accumulate on brain MRI with disease duration and contribute to cognitive decline, depression, and dementia. Severe chronic pain in childhood and adolescence causes school absence, social isolation, and significant psychological morbidity — depression affects approximately 35% of Fabry patients. Infusion-related reactions to ERT (urticaria, fever, rigors) occur in 20–40% of patients and can be managed with pre-medication (antihistamines, paracetamol, corticosteroids) and slowed infusion rates.

There is no prevention for Fabry disease. Genetic counseling is essential for affected families to identify at-risk relatives. Newborn screening programs in some countries detect Fabry disease early before organ damage occurs. Early ERT initiation before significant organ damage is crucial for optimal outcomes. Avoid triggers for pain crises: extreme temperatures, febrile illness, and strenuous exercise. Maintain normal blood pressure and avoid nephrotoxic medications. Annual monitoring of kidney function, cardiac structure, and neurological status guides treatment adjustments and timing of intervention.

Seek medical assessment if you or a family member has: unexplained severe burning pain in the hands and feet particularly triggered by exercise, fever, or heat (acroparesthesiae — the most common early symptom); anhidrosis (inability to sweat normally) causing heat or exercise intolerance; a characteristic skin rash of small reddish-purple spots particularly in the bathing trunk area (angiokeratomas); unexplained stroke or TIA in a young person (below 40) with no conventional risk factors; unexplained progressive kidney disease (proteinuria, declining GFR); unexplained hypertrophic cardiomyopathy; or a first-degree relative diagnosed with Fabry disease (X-linked — all at-risk male and female relatives should be tested). Fabry disease is commonly misdiagnosed for many years — the average diagnostic delay is 14-15 years. If clinically suspected, request alpha-galactosidase A enzyme activity (in leukocytes or plasma — reduced in affected males) and GLA gene sequencing. Females may have normal or near-normal enzyme activity — GLA sequencing is essential. Enzyme replacement therapy (agalsidase alfa or agalsidase beta) significantly slows disease progression when started early.