bird-headed dwarfismA popular term for Seckel syndrome, an autosomal recessive condition characterised by growth and mental retardation, a beak-like nose, micrognathism, microcephaly, prominent maxilla and eyes, hypertelorism, strabismus, anti-mongoloid slant of palpebral fissures, premature balding, short trunk, variable musculoskeletal changes (e.g., kyphoscoliosis, joint dislocations, clubbing of fingers) and genitourinary defects (e.g., cryptorchidism).
Bird-headed dwarfism is divided into four types based on the gene (or locus if the gene has yet to be identified) found defective. The most common is type 1 (OMIM 210600), in which the ataxia-telangiectasia (ATR) and Rad3-related gene, which maps to chromosome 3q22.1-q24, is defective. The protein encoded by ATR plays a central role in DNA repair.
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