Abstract
Morphological variations of human chromosomes due to heterochromatic DNA have been the subject of numerous speculations for a quarter of century. Chromosomal variations or heteromorphisms have been correlated to a number of clinical parameters and a barrage of conflicting views have emerged. An enlarged secondary constriction region [qh] of chromosome 9 and the heterochromatin of the Y chromosome are frequent examples that have been correlated with increased risk of abortions. Recently, we were referred two couples for cytogenetic evaluation, each having three consecutive fetal losses. Both males had very large heterochromatic segments on their Yq chromosomes, while the male of the second couple also had an enlarged qh region on chromosome 16. To the best of our knowledge, such an enlarged qh region on chromosome 16 has not been reported before in combination with a large Y chromosome. A chromosome 16 specific alphoid probe [Oncor] was used to evaluate centromeric size by the FISH technique. A normal size centromere was noted, suggesting that the morphological variation of the long arm of chromosome 16 [16q] was due to the enlarged qh region. Does the male have double trouble or is this a fortuitous finding? Utmost caution should be exercised during counseling of such couples as there are no convincing evidence suggesting heterochromatin plays a role in fetal loss.
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Shklovskaya, T., Kleyman, S., Macera, M. et al. Influence of hcterochromatin on fetal loss: Clinical and counseling aspects. Genet Med 1, 70 (1999). https://doi.org/10.1097/00125817-199901000-00113
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DOI: https://doi.org/10.1097/00125817-199901000-00113