An 8-month-old child presented with reduced appetite, abdominal distension and pain and psychomotor retardation. The child was normal at bih and both parents are normal. O/E: - Hepatosplenomegaly Moderate lymphadenopathy Abnormal posturing of the limbs, trunk, and face Impaired voluntary rapid eye movements Cheery red spot on fundus examination. Bony defects Lymph node-histopathology and electron microscopy. EM findings Which of the following enzymes is most likely deficient in the above disease: -

This is a case of Niemann-pick disease. 1. Autosomal recessive disease 2. Divided into 2 groups depending on deficiency: - Deficiency of acid sphingomyelinase enzyme- Type A and B Impaired intracellular cholesterol trafficking- Type C and D 3. Normal at bih 4. Presents with hepatosplenomegaly, lymphadenopathy and cherry red spot on fundus examination. 5. HPE image shows Niemann-pick cells- These are foam cells with soap suds appearance (Distention of Lysosomes due to sphingomyelin and cholesterol) 6. Electron microscopy shows Zebra bodies - These are concentric lamellated myelin figures (in engorged secondary lysosomes). OTHER ENZYME DEFICIENCIES: - Hexosaminidase A- Tay-sach's disease Alpha-galactosidase A - Fabry's disease Glucocerebrosidase - Gaucher's disease