Interactions between C-bands of chromosomes 1 and 9 in recurrent reproductive loss.

The size of the heterochromatic regions of chromosomes 1 and 16 was measured in a Test group of women with histories of recurrent spontaneous abortion and a Control group of fertile women. Measurements were made on Giemsa banded preparations and the euchromatic regions of 1q and 16q were used to correct for between-cell contraction. For each chromosome pair, the larger and smaller chromosome was identified and populations of each were compared between the two subject groups. For chromosome 1, the smaller chromosome of the Test group was significantly smaller than that of the Control group (P less than 0.001) and the size of the pair difference was larger in the Test than in the Control group (P less than 0.01). For chromosome 16, the smaller chromosome of the Test group was smaller than that of the Control group (5% level). The interaction of chromosome 1 and chromosome 9 heterochromatin in each individual has been analyzed. The combined score for the smaller chromosome 1 and the larger chromosome 9 shows a bimodal distribution and allows discrimination between the two subject groups. Various possible ways in which this interaction might affect reproductive outcome are discussed.