Mechanisms of Meiotic Non-disjunction in Man

Abstract

IT is now well known that there is an abnormal chromosome number in mongolism in chromatin-positive Klinefelter's syndrome, and in chromatin-negative Turner's syndrome. It is also known that mongolism is associated with increased maternal age, and there is some evidence that a similar association exists in chromatin-positive Klinefelter's syndrome^1,2 and in chromatin-negative Turner's syndrome¹. In cases of chromatin-positive Klinefelter's syndrome previously studied the available data (Table 1) provide supporting evidence that there is an association with, among other possibilities, increased maternal age. Fifty four cases were classified with respect to position in the sibship. Four were in the centre of the sibship and of the remaining 50 cases, 17 were in the first half and 33 in the second half. This is significantly different from the expected 25 to 25 distribution.