Boomsma D I, Frants R R, Bank R A, Martin N G
Department of Psychonomics, Free University, Amsterdam, The Netherlands.
Hum Genet. 1992 May;89(3):329-32. doi: 10.1007/BF00220552.
In a sample of 160 Dutch twin pairs and their parents, we found that mothers of dizygotic twins had frequencies of the S and Z alleles at the protease inhibitor (Pi) locus that were 3 times higher than a control sample. Mothers of identical twins also had a higher frequency of S than controls. The S allele may thus both increase ovulation rate and enhance the success of multiple pregnancies. There was also an increased frequency of the S allele in fathers of dizygotic twins; however, this may be a secondary effect of assortative mating for family size (indicating by the number of siblings of the parents), for which a correlation of 0.2 was observed. Parents of dizygotic twins came from larger families than parents of monozygotic twins, but no effect of Pi type on family size was seen.
在一个由160对荷兰双胞胎及其父母组成的样本中，我们发现，异卵双胞胎的母亲在蛋白酶抑制剂（Pi）位点上的S和Z等位基因频率比一个对照样本高3倍。同卵双胞胎的母亲中S等位基因的频率也高于对照组。因此，S等位基因可能既会增加排卵率，又会提高多胎妊娠的成功率。异卵双胞胎的父亲中S等位基因的频率也有所增加；然而，这可能是家庭规模的选型交配（由父母的兄弟姐妹数量表示）的次要效应，观察到其相关性为0.2。异卵双胞胎的父母来自比同卵双胞胎的父母更大的家庭，但未观察到Pi类型对家庭规模的影响。
