Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán", Departamento de Genética, Registro y Vigilancia Epidemiológica de Malformaciones Congénitas, México City, Mexico.
Am J Med Genet C Semin Med Genet. 2011 Nov 15;157C(4):274-87. doi: 10.1002/ajmg.c.30321. Epub 2011 Oct 14.
Conjoined twins (CT) are a very rare developmental accident of uncertain etiology. Prevalence has been previously estimated to be 1 in 50,000 to 1 in 100,000 births. The process by which monozygotic twins do not fully separate but form CT is not well understood. The purpose of the present study was to analyze diverse epidemiological aspects of CT, including the different variables listed in the Introduction Section of this issue of the Journal. The study was made possible using the International Clearinghouse for Birth Defects Surveillance and Research (ICBDSR) structure. This multicenter worldwide research includes the largest sample of CT ever studied. A total of 383 carefully reviewed sets of CT obtained from 26,138,837 births reported by 21 Clearinghouse Surveillance Programs (SP) were included in the analysis. Total prevalence was 1.47 per 100,000 births (95% CI: 1.32-1.62). Salient findings including an evident variation in prevalence among SPs: a marked variation in the type of pregnancy outcome, a similarity in the proportion of CT types among programs: a significant female predominance in CT: particularly of the thoracopagus type and a significant male predominance in parapagus and parasitic types: significant differences in prevalence by ethnicity and an apparent increasing prevalence trend in South American countries. No genetic, environmental or demographic significant associated factors were identified. Further work in epidemiology and molecular research is necessary to understand the etiology and pathogenesis involved in the development of this fascinating phenomenon of nature.
联体双胞胎（CT）是一种非常罕见的发育意外，病因不明。先前的估计患病率为每 50,000 至 100,000 例出生一例。同卵双胞胎不完全分离但形成 CT 的过程尚不清楚。本研究的目的是分析 CT 的多种流行病学方面，包括本期刊介绍部分列出的不同变量。该研究利用国际出生缺陷监测和研究信息交换所（ICBDSR）结构得以实现。这项多中心全球研究包括有史以来对 CT 进行的最大样本研究。总共分析了来自 26,138,837 例出生的 383 组经过仔细审查的 CT 数据集，这些数据来自 21 个信息交换所监测计划（SP）。总患病率为每 100,000 例出生 1.47 例（95%CI：1.32-1.62）。显著发现包括 SP 之间患病率的明显差异：妊娠结局类型明显不同，各计划中 CT 类型的比例相似：CT 中女性明显占优势：特别是胸腹联体双胞胎，而男性在联体和寄生类型中占优势：不同种族之间的患病率存在显著差异，以及南美洲国家中患病率呈明显上升趋势。未发现与遗传、环境或人口统计学相关的显著相关因素。进一步的流行病学和分子研究工作对于理解这种自然现象的发生涉及的病因和发病机制是必要的。
