Holmes L B, Driscoll S G, Atkins L
N Engl J Med. 1976 Feb 12;294(7):365-9. doi: 10.1056/NEJM197602122940704.
We classified 106 stillborn and live-born infants with anencephaly, meningomyelocele, meningocele and encephalocele according to the recognized causes of these malformations. Six different causes were identified, including both genetic and nongenetic disorders; 12 per cent had nongenetic disorders, a chromosome abnormality, or an encephalocele as part of the autosomal recessive Meckel syndrome. Therefore, for this 12 per cent genetic counseling normally provided for isolated anencephaly, meningomyelocele or encephalocele would have been incorrect. If all infants were considered together regardless of cause, the precurrence and recurrence rates of similar malformations in the sibs were 5.2 and 1.7 per cent respectively. However, if infants with other disorders, especially the Meckel syndrome, were excluded, the precurrence and recurrence rates for isolated anencephaly, meningomyelocele and encephalocele among white infants were only 1.7 per cent and 0 per cent. These rates are much lower than the risk of 5 per cent currently being used in genetic counseling in the United States.
我们根据这些畸形的公认病因，对106例死产和活产的无脑儿、脊髓脊膜膨出、脊膜膨出和脑膨出婴儿进行了分类。确定了六种不同的病因，包括遗传和非遗传疾病；12%的患儿患有非遗传疾病、染色体异常或作为常染色体隐性梅克尔综合征一部分的脑膨出。因此，对于这12%的患儿，通常为单纯性无脑儿、脊髓脊膜膨出或脑膨出提供的遗传咨询是不正确的。如果不考虑病因将所有婴儿一起考虑，同胞中类似畸形的先证发病率和复发率分别为5.2%和1.7%。然而，如果排除患有其他疾病的婴儿，尤其是梅克尔综合征患儿，白人婴儿中单纯性无脑儿、脊髓脊膜膨出和脑膨出的先证发病率和复发率仅为1.7%和0%。这些比率远低于美国目前遗传咨询中使用的5%的风险率。
