Gorlin-Goltz syndrome

Correct answer: A. Missing or hypoplastic clavicles

• A. Correct — this is the EXCEPTION. Absent or hypoplastic clavicles (allowing the shoulders to be approximated in front of the chest) belong to CLEIDOCRANIAL DYSPLASIA, not Gorlin-Goltz.
• B. Multiple odontogenic keratocysts are a cardinal feature and are often the presenting sign in adolescence — this is why the dentist frequently makes the diagnosis.
• C. Bifid, splayed or fused ribs are a recognised skeletal feature.
• D. Calcification of the falx cerebri, frontal and parietal bossing, and multiple basal cell carcinomas complete the classic picture.

Correct answer: A. Autosomal dominant

• A. Correct. Gorlin-Goltz syndrome is AUTOSOMAL DOMINANT, caused by mutation of the PTCH1 tumour suppressor gene on chromosome 9q, with high penetrance and variable expressivity.
• B. X-linked dominant is rare; hypophosphatemic (vitamin D-resistant) rickets is the usual example.
• C. X-linked recessive conditions predominantly affect males through carrier mothers — hemophilia A/B is the classic example.
• D. Autosomal recessive would require two affected alleles and typically shows no vertical transmission through generations; Papillon-Lefèvre is the autosomal recessive syndrome commonly tested.

Note: Cleidocranial dysplasia (RUNX2) is ALSO autosomal dominant — do not use inheritance pattern to distinguish these two; use the clinical features.