A patient's condition may follow all of the following patterns of inheritance EXCEPT one. Which is the EXCEPTION?

Correct answer: D. Y-linked

• A. X-linked inheritance is seen in hypohidrotic ectodermal dysplasia, X-linked hypophosphatemic rickets and one form of amelogenesis imperfecta.
• B. Autosomal dominant inheritance is the pattern for dentinogenesis imperfecta, Gardner syndrome, cleidocranial dysplasia and many others.
• C. Autosomal recessive inheritance is common and underlies conditions such as hypophosphatasia and several forms of amelogenesis imperfecta.
• D. CORRECT. Y-linked (holandric) inheritance is vanishingly rare. Only genes in the non-recombining region of the Y chromosome are transmitted this way, exclusively father to son, affecting males only. Essentially no recognized dental or craniofacial condition follows this pattern, which makes it the reliable EXCEPT answer.

Note: Quick screen: if a pedigree shows any affected female, or any father-to-daughter transmission of the trait, Y-linked is excluded immediately.