A 16-year-old boy presents with slowly progressive bilateral loss of central vision. Fundoscopy shows yellow-white pisciform flecks scattered at the level of the retinal pigment epithelium around the macula, and fundus autofluorescence confirms lipofuscin accumulation. Which gene mutation is responsible?

• A ABCA4 on chromosome 1 ✓
• B BEST1 on chromosome 11
• C RHO on chromosome 3
• D RS1 on chromosome Xp22

Explanation

Stargardt disease, the commonest inherited juvenile macular dystrophy, is an autosomal recessive disorder caused by mutations in ABCA4, a photoreceptor ATP-binding cassette transporter involved in vitamin B cycle handling. Accumulated toxic bisretinoid lipofuscin damages the RPE. BEST1 causes Best vitelliform macular dystrophy, RHO causes autosomal dominant retinitis pigmentosa, and RS1 causes X-linked retinoschisis, so each maps onto a different clinical entity.

Reference: Khurana's Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.