Antley-Bixler Syndrome (ABS) is a rare disorder that presents with congenital abnormalities of the head and skeleton. It is associated with mutations that can occur at 2 separate genes.
Abnormalities of the head and face:
(1) craniosynostosis (with brachycephaly, trapezoidocephaly)
(2) mid-facial hypoplasia with flat facies
(3) choanal atresia or stenosis with variable upper airway obstruction
(4) large anterior fontanelle
(5) frontal bossing
(6) proptosis
(7) flattened nasal bridge
(8) long philtrum
(9) small, dysplastic ears with variable auditory dysfunction
(10) variable hydrocephalus
(11) variable preaurical tags
Skeletal abnormalities may include:
(1) radiohumeral synostosis
(2) multiple joint contractures
(3) anterior bowing of the femurs with neonatal fractures
(4) arachnodactyly with distal tapering of digits
(5) camptodactyly
(6) scoliosis
(7) humeral bowing
Miscellaneous abnormalities:
(1) atrial septal defect (ASD)
(2) renal malformation
(3) multiple hemangiomata
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Type
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Distinguishing Features
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Genetic Defect
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Type 1
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normal steroidogenesis and genitalia
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FGFR2 (10q26)
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Type 2
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congenital adrenal hyperplasia with impaired steroidogenesis and ambiguous genitalia
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POR (7q11.2)
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where:
• POR = cytochrome p450 oxidoreductase
