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Medical Definition of Chromosome 16
1. Trisomy 16, the most common autosomal aneuploidy encountered in spontaneous abortuses, is rarely diagnosed in ongoing pregnancies and is considered lethal. However, cases of trisomy 16 mosaicism ascertained either by amniocentesis or in liveborn infants are reported. The liveborns exhibit a distinct and recognizable phenotype of highly variable severity, with multiple congenital anomalies and dysmorphic features including asymmetry, intrauterine growth retardation, congenital heart disease, respiratory tract and musculoskeletal defects. The phenotype of 16p trisomy includes considerable intrauterine and postnatal growth retardation, small round skull, scant lashes and eyebrows, round flat face, prominent maxillae, micrognathia, round low-set ears with hypoplastic tragus and helix and protuberant anthelix, aplasia or hypoplasia of the thumb and severe mental impairment. All reported cases of complete or partial duplication of 16q result from a parental translocation. Frequent findings include growth retardation, mental handicap, asymmetrical head, high forehead, short prominent or beaked nose, long philtrum and thin upper lip. Osteoarticular and perineal anomalies are constant. Duplication 16q13 shows multiple malformations including ambiguous genitalia, congenital heart disease, syndactyly and unusual facies including downslanting palpebral fissures, low set ears with severe unilateral microtia, micrognathia and cleft palate. Chromosome 16 gene assignments include the alpha-globin genes, whose mutations cause thalassaemias, and the genes for haptoglobin, adult polycystic kidney disease, and others. (05 Mar 2000)
Lexicographical Neighbors of Chromosome 16
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