The Antley–Bixler syndrome

Antley-Bixler syndrome (ABS) is an autosomal recessive, exceptionally rare craniosynostosis syndrome characterized by radiohumeral synostosis present from the perinatal period. It is a rare genetic disorder that can cause structural changes of the skull, bones of the face and other skeletal abnormalities. The disorder is typically associated with premature closure of joints (cranial sutures) between particular bones of the skull (craniosynostosis).

It was first described in 1975 by Antley and Bixler, and since then fewer than 50 cases have been reported in the literature.

Mortality has been reported to be as high as 80% in the neonatal period, primarily due to airway compromise, and prognosis improves with increasing age.

Antley-Bixler syndrome primarily manifests with brachycephali, sever mid-face hypoplasia, craniosynostosis, radiohumeral synostosis, femoral bowing and spontaneous long-bone fractures. Other manifestations comprise choanal atresia as well as stenosis, loss of hearing, agenesis of kidneys, proptosis, arachnodactilia, heart malformations and, in some patients, disordered steroidogenesis and ambiguous genitalia.

The exact causes of Antley Bixler syndrome is unknown in many cases; however, some are due to changes (mutations) in the FGFR2 gene or the POR gene. There appear to be autosomal dominant and autosomal recessive forms of the condition.
The Antley–Bixler syndrome