A 10-year-old mentally and physically retarded girl has a mosaic ring-4 chromosome. The number of ring chromosomes in her peripheral blood preparations has increased from 9% to 72% in the past seven years. The child had a low birth weight and has had several phenotypic changes.
Parker CE, Alfi OS, Derencsenyi A, Mavalwala J, Donnell G. A Child With a Ring-4 Chromosome (46,XX/46,XX,r 4). Am J Dis Child. 1974;128(3):371-374. doi:10.1001/archpedi.1974.02110280101015