Down's syndrome with a familial D/D reciprocal translocation and a G/G chromosome.

The presence of a translocation between two chromosomes in the I3-I5 (D) group does not usually give rise to any phenotypical abnormality and may be relatively common in the population (Hamerton, Giannelli, and Carter, I963). Such translocations have, however, been reported in a patient with XXY Klinefelter's syndrome (Lejeune, Turpin, and DeCourt, i960), and Hamerton et al. (I963) describe a family in which the mother of a 2I trisomic mongol was found to have a D/D translocation and also cite a case of a 2I trisomic mongol with a D/D translocation. The present report describes a case of a Down's syndrome in which such a translocation was found in association with a G/G translocation.