23rd May 2025

A child attends the GP surgery for his preschool vaccinations.

A child attends the GP surgery for his preschool vaccinations. He has failed to meet his developmental milestones and is on the 10th centile for height and weight. 

He has required multiple courses of antibiotics for recurrent sinusitis and otitis media.

You note the presence of a small mouth and chin, prominent ears, as well as a healed surgical scar on his upper lip. Given the underlying diagnosis, where is the gene defect?

Select the SINGLE most appropriate option from the list below. Select ONE option only.