Ring 21 chromosome: the mild end of the phenotypic spectrum.
The case is reported of a child with the karyotype 46,XY,r(21), who presented with linear growth retardation but who appears, at age 2 years 8 months, to be developing normally mentally. There is a small number of reports of mildly affected cases of r(21), and of some with an apparently completely normal phenotype. We presume a structural and functional cytogenetic heterogeneity underlies the observed phenotypic heterogeneity in the ring 21 spectrum.
D002675:Child, Preschool; D002869:Chromosome Aberrations; D002891:Chromosomes, Human, Pair 21; D006130:Growth Disorders / Q000235:genetics; D006345:Heart Septal Defects, Ventricular / Q000235:genetics; D006801:Humans; D008297:Male; D010641:Phenotype; D012303:Ring Chromosomes