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Down's syndrome with a recombinant tandem duplication of chromosome 21 derived from a maternal ring.

1984; BMJ; Volume: 21; Issue: 4 Linguagem: Inglês

10.1136/jmg.21.4.310

1468-6244

R T Howell, Alan McDermott, A. Gardner, V. Dickinson,

Genomics and Rare Diseases

An account is given of the cytogenetic investigations of a girl with Down's syndrome found to have a dicentric duplication of chromosome 21. This tandem type of rearrangement was interpreted as a recombinant derived from a single meiotic crossover between a maternal ring 21 and its normal homologue. A population of cells was also found in which breakage of the dicentric resulted in a chromosome 21 with a small terminal deletion. The mother and the proband's younger brother, who was also a ring 21 heterozygote, were both clinically normal.