The 3MC syndromes types 1–3 (MIM#257920, 265050 and 248340, respectively) are rare autosomal recessive genetic disorders caused by pathogenic variants in genes encoding the lectin complement pathway. Patients with 3MC syndrome have a distinctive facial phenotype including hypertelorism, highly arched eyebrows and ptosis. A significant number of patients have bilateral cleft lip and palate and they often exhibit genitourinary and skeletal anomalies. A clinical clue to 3MC syndrome is the presence of a characteristic caudal appendage. Genetic variants in MASP1, COLEC11 and COLEC10 genes have been identified as the causation of this syndrome, yet relatively few patients have been described so far. We consolidate and expand current knowledge of phenotypic features and molecular diagnosis of 3MC syndrome by describing the clinical and molecular findings in five patients. This includes follow-up of two brothers whose clinical phenotypes were first reported by Crisponi et al in 1999. Our study contributes to the evolving clinical and molecular spectrum of 3MC syndrome.

1-3 型 3MC 综合征（分别为 MIM#257920、265050 和 248340）是罕见的常染色体隐性遗传疾病，由编码凝集素补体途径的基因致病性变异引起。3MC 综合征患者具有独特的面部表型，包括距离过远、眉毛高拱和上睑下垂。大量患者患有双侧唇裂和腭裂，并且经常表现出泌尿生殖和骨骼异常。3MC 综合征的临床线索是特征性尾肢的存在。MASP1、COLEC11和COLEC10基因的遗传变异已被确定为该综合征的病因，但迄今为止描述的患者相对较少。我们通过描述 5 名患者的临床和分子发现来巩固和扩展当前对 3MC 综合征表型特征和分子诊断的知识。这包括对两兄弟的随访，他们的临床表型由Crisponi 等人于 1999 年首次报道。我们的研究有助于不断发展 3MC 综合征的临床和分子谱。