An 11-year-old boy has episodes of burning pain in his palms and soles triggered by exercise and hot weather, relieved by cold. Examination reveals small dark-red punctate macules clustered around the umbilicus, hips, and scrotum, along with cornea verticillata on slit-lamp examination. Renal biopsy shows lamellar zebra bodies within lysosomes of podocytes. Deficient activity of which enzyme is expected?

• A Sphingomyelinase
• B Galactocerebrosidase
• C Alpha-galactosidase A ✓
• D Acid ceramidase

Explanation

Fabry disease is an X-linked lysosomal storage disorder caused by alpha-galactosidase A deficiency, leading to accumulation of globotriaosylceramide. Classic findings are childhood acroparaesthesiae (burning extremity pain worsened by heat and exercise), angiokeratomas in a bathing-trunk distribution, cornea verticillata, hypohidrosis, cardiomyopathy, renal failure, and strokes. Zebra bodies on electron microscopy confirm glycosphingolipid deposition. Sphingomyelinase, galactocerebrosidase, and acid ceramidase correspond to Niemann-Pick A/B, Krabbe, and Farber diseases respectively.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.