, Volume 47, Issue 5, pp 429-432
Date: 19 Aug 2010

Phenotypic heterogeneity and parental origin of extra chromosome 21 in Down syndrome

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Abstract

We compared the frequency of phenotypic features of 40 children with Down syndrome between individuals with a maternally or paternally derived extra chromosome 21, using quantitative FISH for comparing heteromorphisms of the nucleolar organizing region. Parental origin was determined in 90% of families. Hypotonia and craniofacial abnormalities were present in 90% or more individuals, irrespective of parental origin of chromosome 21. Congenital heart defects were more frequent in cases with a maternally derived extra chromosome 21. Imprinted gene(s) may contribute to the development of congenital heart defects in Down syndrome.