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母亲年龄增加对某些三体发生率的影响是人所共知的,在三体中了解最清楚的是21三体(Down综合征)。但是13三体、18三体和许多其它常染色体三体以及XXX、XXY都和母亲的年龄有关。然而在少数染色体异常的病例中却发现了母亲年龄的相反效应(母亲年龄增加,染色体异常发生率降低)。X单体(45)正是这样的染色体异常。本文收集两份材料,一份是1971年1月至1975年12月在日内瓦收集的447例自然流
It is well known that the impact of increased maternal age on the prevalence of some trisomics is best understood in trisomy 21. However, trisomy 13, trisomy 18, and many other autosomal trisomies, as well as XXX, XXY, are all related to the age of the mother. However, in the rare cases of chromosomal abnormalities, the opposite effect of mother’s age was found (mother’s age was increased and the incidence of chromosomal abnormalities was reduced). X monomer (45) is exactly such a chromosomal abnormality. This article collects two pieces of information, one of 447 natural flows collected in Geneva from January 1971 to December 1975