Camptomelic Dysplasia

This is camptomelic, or campomelic, dysplasia. It is a rare, often lethal skeletal dysplasia caused by mutation or disruption of SOX9, usually arising de novo. The skeletal hallmark, which the case shows, is congenital bowing of the long bones - camptomelia - characteristically anterior bowing of the tibia, often with a skin dimple over the apex of the bow, together with hypoplastic scapulae, a reduced number of rib pairs, scoliosis, clubfeet and a small thorax. The respiratory distress reflects the principal cause of the high mortality: the small thorax combined with laryngotracheomalacia, a softening of the airway cartilage that follows from the SOX9 chondrogenesis defect, causing airway collapse and respiratory failure that is frequently fatal in the neonatal period. The clinching clue here is the discordance between a 46,XY karyotype and female-appearing genitalia - XY sex reversal - which occurs because SOX9 is essential for testis determination; this directly links the skeletal phenotype to the SOX9 gene. I would confirm the diagnosis with SOX9 genetic testing and the karyotype, and look for associated anomalies such as cleft palate and Pierre Robin sequence. Management is largely supportive and palliative given the high mortality, with neonatal airway and respiratory support as the immediate priority and an honest prognostic discussion with the family; for the minority who survive, orthopaedic care addresses the limb bowing, scoliosis and foot deformity, alongside endocrine and genetic input.