假设母亲年龄对21——三体的影响认定是因卵子发生时出现错误分配所致,那么随着母亲年龄的增加.母源病例与父源病例之比 M:P 值将会明显地增加.可是对具标记染色体的父源三体性的研究却报道 M:P 的值随母亲年龄变化很小,因此又有人认为:年龄效应源自母亲的年龄,而母亲年龄又受胎儿流产的影响(这里不考虑父源问题).不过许多人对支持这个假设持保留意见.实际上对染色体多态性这一细胞遗传学证据的可靠性人们也产生了怀疑。但是,要确认大多数研究是否是由于技术所限,这在亲源被确定之前需要作二或三次一致性的观察.就是这样某些错误还是会发生.因为21——三体病例的大多数基于母源,而父源的锴误分配导致出现错误类别的比例又比那些母源病的比例要高.所以,假如 M:P Assuming that the effect of maternal age on trisomy 21 is due to a misallocation of the egg, the M: P ratio of maternal and paternal cases will increase significantly as the mother’s age increases. However, studies of paternal trisomy with labeled chromosomes reported that the value of M: P varies little with the age of the mother, and therefore some people think that the age effect is due to the age of the mother and that the age of the mother is affected by fetal abortion Fatherhood problems are not considered here.) But many people have reservations about supporting this hypothesis, and indeed the suspicion of the reliability of cytogenetic evidence of chromosomal polymorphism. However, to confirm whether most of the studies are due to technical limitations, this would require two or three coherence observations before the progeny were identified, which is why some of these mistakes still occur because most of the 21-trisomy cases Based on the maternal source, the misclassification of the paternal source leads to a higher proportion of error categories than maternal sources, so if M: P