A couple with a family history of otosclerosis seeks genetic counselling. What is the established mode of inheritance of otosclerosis?

• A Autosomal recessive with complete penetrance
• B Autosomal dominant with approximately 40% penetrance ✓
• C X-linked dominant
• D Mitochondrial maternal inheritance

Explanation

Otosclerosis is inherited as an autosomal dominant trait with incomplete penetrance of about 40%, so many carriers never develop clinical disease. Several loci have been mapped, including OTSC1 on chromosome 15q. Recessive, X-linked and mitochondrial patterns are not supported by pedigree studies, and the low penetrance explains why a positive family history is common yet many relatives are unaffected.

Reference: Dhingra's Diseases of Ear, Nose and Throat, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.