Phenotypic heterogeneity and parental origin of extra chromosome 21 in Down syndrome.
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.
Muranjan
Mamta
M
Department of Pediatrics, Genetic Clinic, KEM Hospital, Parel, Mumbai, India. muranjanmamta@rediffmail.com
Chaudhari
Tejasvi
T
Vundinti
Babu Rao
BR
D000328:Adult; D002675:Child, Preschool; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics*; D004314:Down Syndrome / Q000235:genetics*; D005111:Extrachromosomal Inheritance / Q000235:genetics*; D005260:Female; D018392:Genomic Imprinting; D006330:Heart Defects, Congenital; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D008297:Male; D008875:Middle Aged; D010290:Parents; D010641:Phenotype