STRUCTURAL VARIATIONS OF CHROMOSOME 9

Partial trisomy of chromosome 9 has relatively frequently been observed in liveborn subjects. In the majority of the reported cases breaks occur in the centric segment of the long arm (q11-q13). Two characteristics of this chromosome part, i.e. 9qh+ and inv(9), have been studied. The results of a study of selected samples do not support an association between 9qh+ chromosome anomaly and reproductive failure. The frequency of inv(9) in different samples agrees with those reported by other investigators (1.11—2.32%). An excess of male carriers was found. Aneusomy of recombination has been observed in one case. Partial trisomy of chromosome seems to be the most frequently observed type of unbalanced structural aberration of autosomes in liveborn subjects. Up to now 50 cases have been reported. Three of these have been described as 9q trisomy, the others were 9p trisomies