A 6-month-old infant presents with progressive psychomotor regression, hyperacusis, an exaggerated startle response, and a cherry-red spot on fundoscopy. Enzyme assay confirms hexosaminidase A deficiency. What is the INHERITANCE pattern?

• A Autosomal recessive ✓
• B Autosomal dominant
• C X-linked recessive
• D Mitochondrial inheritance

Explanation

This is Tay-Sachs disease, a GM2 gangliosidosis caused by deficiency of hexosaminidase A (HEXA gene mutation), leading to accumulation of GM2 ganglioside in neurons. It follows autosomal recessive inheritance and has high prevalence in Ashkenazi Jewish populations. The cherry-red spot results from contrast between the avascular fovea and surrounding lipid-laden ganglion cells. There is no effective treatment; death typically occurs by age 4-5 years. All lysosomal storage disorders are autosomal recessive except Fabry and Hunter syndrome (X-linked).

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.