A 19-year-old man has episodic burning pain in his palms and soles, clusters of dark red vascular skin lesions over the lower trunk, corneal verticillata on slit lamp examination, and increasing proteinuria. Family history reveals a maternal uncle who died of renal failure. Electron microscopy of the kidney biopsy shows concentric lamellated myelin-like inclusion bodies (zebra bodies) within podocyte lysosomes. The deficient enzyme is:

• A Alpha galactosidase A ✓
• B Sphingomyelinase
• C Hexosaminidase A
• D Glucocerebrosidase

Explanation

Fabry disease is an X-linked deficiency of alpha galactosidase A leading to accumulation of globotriaosylceramide (ceramide trihexoside) in vascular endothelium, podocytes, and other cells. Zebra bodies, concentric lamellated lysosomal inclusions on electron microscopy, are its renal ultrastructural hallmark, and affected males develop progressive proteinuria and renal failure. Sphingomyelinase deficiency defines Niemann Pick disease, hexosaminidase A deficiency Tay Sachs disease, and glucocerebrosidase deficiency Gaucher disease.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.