Orioli I M, Castilla E E
ECLAMC (Latin-American Collaborative Study of Congenital Malformations, WHO Collaborating Centre for the Prevention of Birth Defects) at Departamento de Genética, Universidade Federal do Rio de Janeiro, Brazil.
Am J Med Genet. 1999 Jan 29;82(3):219-24.
It was recently shown that hand postaxial polydactyly differed from foot postaxial polydactyly. The aim of this work was to test whether thumb and hallux duplication also had different clinical and epidemiological characteristics, depending on limb involvement. We studied 920 newborn infants with first digit duplication, ascertained among 3,444,374 births by the Latin-American Collaborative Study of Congenital Malformations (ECLAMC), from 1967 to 1995. Since biphalangeal thumb duplication or hallux duplication can occur in families with triphalangeal thumb or polysyndactylous propositi, these groups were also analyzed. The 715 isolated (nonsyndromal) cases (prevalence 2.08 per 10,000) were subdivided into five groups: thumb duplication (N = 568; prevalence: 1.65/10,000); hallux duplication (N = 82; prevalence: 0.24); thumb and/or hallux duplication plus syndactyly (polysyndactyly) (N = 37; prevalence: 0.11); triphalangeal thumb (N = 24; prevalence: 0.07), and thumb duplication plus hallux duplication (N = 4; prevalence: 0.01). Both thumb and hallux duplication groups showed a significant excess of males, and right sidedness was also more frequent in both of them, though without statistical significance for hallux duplication. Thumb duplication was more often unilateral (94.7% versus hallux duplication of 81.5%), and its prevalence was higher in Bolivia (3.37/10,000) than in the other 10 Latin-American countries included (1.62/10,000). In a subseries of 405 preaxial polydactylies with matched controls, a logistic regression analysis showed that birth weight and gestational age had an effect on the calculated risk of having an infant with thumb duplication, while first trimester vaginal bleeding had only a borderline effect. None of the polydactyly groups showed abnormal values for twinning, perinatal mortality, ethnicity, maternal education, parental ages, parity, parental subfertility, or consanguinity. There were 70/405 familial cases. Their pedigrees were compatible with autosomal dominant inheritance with a 9% penetrance for thumb duplication and hallux duplication and a 70% penetrance for triphalangeal thumb and polysyndactyly. Inheritance of thumb duplication and probably the untested inheritance of hallux duplication were also compatible with a four-locus multiplicative model. The observed differences in laterality, geographical distribution, birth weight, gestational age, and first trimester vaginal bleeding between thumb duplication and hallux duplication groups suggested that apparent preaxial polydactyly type 1 is a causally heterogeneous group.
最近研究表明，手部轴后多指畸形与足部轴后多指畸形有所不同。本研究的目的是检验拇指和拇趾重复畸形是否也因肢体受累情况而具有不同的临床和流行病学特征。我们研究了920例患有第一指重复畸形的新生儿，这些病例是在1967年至1995年拉丁美洲先天性畸形协作研究（ECLAMC）的3444374例出生病例中确定的。由于在具有三指节拇指或多指畸形先证者的家庭中可能出现双指节拇指重复或拇趾重复，因此也对这些群体进行了分析。715例孤立（非综合征性）病例（患病率为每10000例中有2.08例）被分为五组：拇指重复（N = 568；患病率：1.65/10000）；拇趾重复（N = 82；患病率：0.24）；拇指和/或拇趾重复合并并指（多指畸形）（N = 37；患病率：0.11）；三指节拇指（N = 24；患病率：0.07），以及拇指重复合并拇趾重复（N = 4；患病率：0.01）。拇指和拇趾重复畸形组均显示男性明显过多，且两者右侧受累也更常见，不过拇趾重复畸形的这一情况无统计学意义。拇指重复畸形更常为单侧（94.7%，而拇趾重复畸形为81.5%），其患病率在玻利维亚（3.37/10000）高于其他10个拉丁美洲国家（1.62/10000）。在一个有匹配对照者的405例轴前多指畸形的子系列中，逻辑回归分析表明出生体重和孕周对计算得出的生育患有拇指重复畸形婴儿的风险有影响，而孕早期阴道出血仅有边缘性影响。没有一个多指畸形组在双胎妊娠、围产期死亡率、种族、母亲教育程度、父母年龄、产次、父母生育力低下或近亲结婚方面显示出异常值。有70/405例家族性病例。其系谱符合常染色体显性遗传，拇指重复和拇趾重复的外显率为9%，三指节拇指和多指畸形的外显率为70%。拇指重复的遗传以及可能未经检验的拇趾重复的遗传也符合一个四位点乘法模型。拇指重复畸形组和拇趾重复畸形组在偏侧性、地理分布、出生体重、孕周和孕早期阴道出血方面观察到的差异表明，明显的1型轴前多指畸形是一个病因异质性群体。
