Ng Zhi Yang, Sau Po Yi, Lim Gale Jue-Shuang
From the Departments of *Plastic Reconstructive and Aesthetic Surgery, †Obstetrics and Gynecology, and ‡Orthopedic Surgery, KK Women's and Children's Hospital, Singapore, Singapore.
Ann Plast Surg. 2015 Oct;75(4):398-400. doi: 10.1097/SAP.0000000000000336.
There are 4 types of preaxial polydactyly (PPD), and type I (PPD-I), also known as thumb duplication, is the most common. This frequently encountered condition has since been further described and classified by Wassel based on the level of duplication of skeletal anatomy. Genetic studies have localized possible candidate gene(s) for PPD types II to IV to the chromosomal region 7q36 but the current literature attributes PPD-I to isolated, spontaneous mutations typically with unilateral involvement only. Recent epidemiological studies have also suggested nongenetic causes for PPD-I including social and environmental factors. Herein, we would like to present a case of discordant PPD-I expression affecting the same hand in a pair of monozygotic twins and suggest possible reasons for this presentation because previous similar reports only had involvement of 1 child.
有4种类型的轴前多指（PPD），其中I型（PPD-I），也称为拇指重复，是最常见的。此后，瓦塞尔根据骨骼解剖结构的重复水平对这种常见病症进行了进一步描述和分类。基因研究已将PPD II至IV型的可能候选基因定位到染色体区域7q36，但目前的文献将PPD-I归因于孤立的自发突变，通常仅单侧受累。最近的流行病学研究也表明PPD-I存在非遗传原因，包括社会和环境因素。在此，我们想介绍一对同卵双胞胎同一手部出现不一致PPD-I表达的病例，并提出这种表现的可能原因，因为之前的类似报告仅涉及1名儿童。
