一对男性双胞胎中的一个存在畸形；他们会是同卵双胞胎吗？一个诊断难题。

Department of Pediatrics, Consultant Pediatrician, Aminu Kano Teaching Hospital,/Bayero University Kano, Kano State, Nigeria.

J Family Med Prim Care. 2014 Jul;3(3):281-3. doi: 10.4103/2249-4863.141646.

Twinning occurs worldwide, but Nigerian women of the southwest extraction record one of the highest rates in the world. Among the notable risk factors for fraternal twinning is advanced maternal age, which is also an independent risk factor for Down syndrome. Even as morphological characteristics can easily be applied to distinguish identical from fraternal twins, in cases of an associated dysmorphism, in any member of the couplet, it becomes a difficult tool to use, as has been observed in the case of a set of twins who were of the same sex, blood group, hemoglobin genotype, and shared the same placenta.

双胞胎现象在全球范围内都有发生，但祖籍为尼日利亚西南部的女性的双胞胎出生率位居世界前列。异卵双胞胎的显著风险因素之一是母亲年龄较大，而这也是唐氏综合征的一个独立风险因素。尽管形态特征很容易用于区分同卵双胞胎和异卵双胞胎，但在双胞胎中有任何一方存在相关畸形的情况下，它就成了一个难以使用的工具，就像在一对性别相同、血型相同、血红蛋白基因型相同且共用一个胎盘的双胞胎案例中所观察到的那样。