A 3-year-old boy from rural Maharashtra presents with progressive hepatosplenomegaly, developmental delay, and cherry-red spot on the macula on fundoscopy. Bone marrow examination shows foamy macrophages. Enzyme assay reveals deficiency of hexosaminidase A. What is the most appropriate next step in management?

Explanation

## Clinical Diagnosis This child has **Tay-Sachs disease** (GM2 gangliosidosis Type I), confirmed by: - Cherry-red spot on macula (pathognomonic) - Hepatosplenomegaly and developmental delay - Foamy macrophages (storage cells) - Hexosaminidase A (Hex-A) deficiency ## Management Strategy for Lysosomal Storage Disorders **Key Point:** Lysosomal storage disorders (LSDs) are currently incurable. Management is primarily **supportive care and genetic counselling**. ### Why Genetic Counselling is the Next Step 1. **Autosomal recessive inheritance** — both parents are carriers; risk of recurrence in future pregnancies is **25%** 2. **Prenatal diagnosis available** — amniocentesis/CVS with enzyme assay or genetic testing can identify affected fetuses 3. **No disease-modifying therapy** for Tay-Sachs at present — enzyme replacement therapy (ERT) and gene therapy are experimental/not standard of care 4. **Family planning** — parents need informed counselling about reproductive options ### Supportive Care Measures (Concurrent) - Anticonvulsants for seizures - Nutritional support and feeding assistance - Palliative care as disease progresses - Physiotherapy to maintain function **High-Yield:** The diagnosis of an LSD in a child mandates **immediate genetic counselling** for the family, regardless of the specific disorder. This is the standard of care and the most appropriate next step. ## Why Other Options Are Incorrect | Option | Why Not | Explanation | |--------|---------|-------------| | N-acetylcysteine | No role in Tay-Sachs | Used in acetaminophen toxicity, not LSDs | | Bone marrow transplant | Ineffective at this stage | May have limited benefit in infantile-onset disease; not standard for Tay-Sachs; requires early intervention before neurological damage | | Vitamin B6 | Specific to different disorder | High-dose B6 is used in homocystinuria and primary hyperoxaluria, not gangliosidoses | **Clinical Pearl:** Tay-Sachs is invariably fatal by age 4–5 years in the infantile form. The focus shifts to family counselling, symptom management, and prevention of recurrence.