并指（趾）畸形的分类及遗传学研究进展

并指（趾）畸形（syndactyly，SD）是最常见的遗传性肢体畸形，表现为某些手指或脚趾的融合。这类畸形可单独出现，也可以作为300多种综合征的一个体征出现。SD在家庭间及家庭内部具有显著的临床异质性。即使在同一个体中，表型也可表现为单侧或双侧，对称或不对称。目前，已经报道的非综合征型的SD至少9种，主要遗传模式为常染色体显性遗传，其次是常染色体隐性遗传及X-连锁隐性遗传。其中Ⅱ-a，Ⅲ，Ⅳ，Ⅴ，Ⅶ，Ⅷ型的SD致病基因及其突变位点已经找到，其他SD的遗传学机制仍然未知。在Sajid Malik分类的基础上，系统总结近几年SD的遗传研究成果，以期为该病机制的深入研究和临床诊断提供帮助。

Syndactyly: Classification and Genetics

Syndactyly (SD) is one of the most common hereditary limb malformations depicting the fusion of certain fingers or toes. It may occur as an isolated entity or a component of more than 300 syndromic anomalies. Syndactylies exhibit great inter- and intra-familial clinical variability. Phenotype can be unilateral or bilateral and symmetrical or asymmetrical within a subject. At least nine non-syndromic syndactylies have been characterized. Most of the syndactyly types are inherited as autosomal dominant but two autosomal recessive and an X-linked recessive entity have also been described. Whereas the underlying genes/mutations for types Ⅱ-a,Ⅲ, Ⅳ, Ⅴ, Ⅶ and Ⅷ have been worked out, the etiology and molecular basis of the other syndactyly types remain unknown. In this communication, based on the classification of Sajid Malik, we summarized the results of genetic studies on syndactyly in recent years, which will contribute to further investigation of the pathogenic mechanism and implementation of genetic diagnosis of syndactyly.