Chromosomal Translocations in Patients with Mongolism and in Their Normal Relatives

MONGOLISM is usually the result of trisomy of a small acrocentric chromosome in Group 21–22 in the Denver Classification. This is generally referred to as 21-trisomy. These patients have a somatic chromosome number of 47.1 However, a number of cases of mongolism with a somatic chromosome number of 46 have been reported. In almost all these, karyotype analyses have revealed the probable presence of a translocation, usually between chromosomes 14 or 15 and 212 3 4 but in some cases between 21 and 22.3 , 5 In the families so far described, the translocation has been present in otherwise normal mothers as well as . . .