Antley–Bixler syndrome

Antley–Bixler syndrome
Synonyms	Trapezoidocephaly-synostosis syndrome,
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Antley–Bixler syndrome, is a rare, very severe autosomal recessive congenital disorder characterized by malformations and deformities affecting the majority of the skeleton and other areas of the body.

Presentation

Antley–Bixler syndrome presents itself at birth or prenatally. Features of the disorder include brachycephaly (flat forehead), craniosynostosis (complete skull-joint closure) of both coronal and lambdoid sutures, facial hypoplasia (underdevelopment); bowed ulna (forearm bone) and femur (thigh bone), synostosis of the radius (forearm bone), humerus (upper arm bone) and trapezoid (hand bone); camptodactyly (fused interphalangeal joints in the fingers), thin ilial wings (outer pelvic plate) and renal malformations.

Other symptoms, such as cardiac malformations, proptotic exophthalmos (bulging eyes), arachnodactyly (spider-like fingers) as well as nasal, anal and vaginal atresia (occlusion) have been reported.

Pathophysiology

There are two distinct genetic mutations associated with the Antley–Bixler syndrome phenotype, which suggests the disorder may be genetically heterogeneous.

OMIM	Gene	Description
207410	FGFR2	Mutations found in the FGFR2 gene have been shown to cause synostosis and other formal skeletal, polydactylic and syndactylic abnormalities found in Antley–Bixler and similar disorders.
201750	POR	A missense mutation in the cytochrome P450 reductase (POR) gene results in abnormal steroidogenesis related to the genital malformations often found in Antley-Bixler. In OMIM, this is classified as an "Antley–Bixler syndrome-like phenotype" and not as Antley–Bixler syndrome itself.

Antley–Bixler syndrome is inherited in an autosomal recessive pattern, which means the defective gene is located on an autosome, and two copies of the gene (one inherited from each parent) are required to be born with the disorder. The parents of an individual with an autosomal recessive disorder both carry one copy of the defective gene but are usually not affected by the disorder.

Eponym

Antley–Bixler syndrome is named after Drs. Ray M. Antley (b. 1936) and David Bixler (b. 1929), who first described the disorder in a journal report from 1975.

See also

• Cytochrome P450 oxidoreductase deficiency
• Crouzon syndrome
• Jackson–Weiss syndrome
• Pfeiffer syndrome

Further reading

• GeneReviews/NIH/NCBI/UW entry on FGFR-Related Craniosynostosis Syndromes
• GeneReviews/NCBI/NIH/UW entry on Cytochrome P450 Oxidoreductase Deficiency

External links

Classification	ICD-10: Q87.0 OMIM: 207410 MeSH: D054882
External resources	Orphanet: 83