目的：总结MAB21L2基因的变异和临床特点，并与高度同源的MAB21L1基因进行比较。 方法：对中山眼科中心临床基因数据库中MAB21L2基因变异患者进行基因型和表型分析，回顾性分析既往文献报道的MAB21L2基因和高度同源基因MAB21L1变异的表型-基因型的关系。结果：在2个小眼畸形家系中发现2个MAB21L2基因杂合变异：先证者1携带已知变异c.151C>G/p.(Arg51Gly)，患者双眼小眼畸形伴虹膜脉络膜缺损，伴骨关节屈曲。母亲携带相同杂合变异但表型正常；先证者2携带未报道的变异c.1042G>T/p.(Glu348*)，左眼小眼畸形，右眼正常且无全身异常。结合文献回顾发现，在显性遗传模式下，80%的MAB21L2杂合致病变异(20/25)和100%的MAB21L1杂合致病变异(25/25)发生在氨基酸49-52 区域，导致小眼无眼或眼缺损异常(microphthalmia, anophthalmia or coloboma,MAC)；携带该区域MAB21L2基因杂合突变的患者除MAC外，部分还伴骨骼关节发育异常(12/24，50%)；杂合截短变异发生在MAB21L2基因可导致MAC(5/5，100%)，而发生在MAB21L1则不致病。 结论：在2个小眼畸形家系中发现了MAB21L2基因1个新致病变异和1个已知热点致病变异，通过文献综述比较和总结了MAB21L1和MAB21L2基因的突变频谱以及基因型-表型相互关系，为此类基因缺陷导致遗传病的诊断和鉴别诊断提供依据。
Objective: To summarize the genetic variations and clinical features of the MAB21L2 and compare them with the highly homologous MAB21L1 gene. Methods: A genotype -genotype analysis was performed on the patients with MAB21L2 gene variants in the clinical genetic database of Zhongshan Ophthalmic Center, Sun Yat-sen University. A retrospective review was undertaken to analyze the phenotype-genotype correlations of MAB21L2 gene variants and the highly homologous MAB21L1 gene variants reported in the previous literature. Results: Two heterozygous MAB21L2 gene variants were identified in two families with microphthalmia: Proband 1 carried the known variant c.151C>G/p.(Arg51Gly), presenting with bilateral microphthalmia with iris-choroidal coloboma and flexion of joints. The mother carried the same heterozygous variant but had a normal phenotype. Proband 2 carried the unreported variant c.1042G>T/p.(Glu348*), manifesting as left-sided microphthalmia with a normal right eye and no other systemic abnormalities. Through literature review, we found that under a dominant inheritance pattern, 80% of heterozygous pathogenic MAB21L2 variants (20/25) and 100% of heterozygous pathogenic MAB21L1 variants (25/25) occurred in the amino acid region 49-52, resulting in microphthalmia, anophthalmia, and coloboma (MAC). Some patients with heterozygous MAB21L2 variants in this region exhibited additional skeletal and joint dysplasia (12/24, 50%). Heterozygous truncating variants in MAB21L2 led to MAC (5/5, 100%), while those in MAB21L1 were non-pathogenic. Conclusions: This study identified a novel pathogenic variant and a known hotspot pathogenic variant of MAB21L2 in two families with microphthalmia. Through a comprehensive literature review, we compared and summarized the mutation spectrums and genotype-phenotype correlations of MAB21L1 and MAB21L2 genes, providing valuable insights for the diagnosis and differential diagnosis of genetic diseases caused by these gene defects.
先天性小眼畸形是一种罕见的先天性眼球发育异常，表现为眼球体积缩小和结构紊乱，常伴有眼组织缺损，严重影响患者的视觉功能。该病可单独发生，仅影响眼部，也可作为全身综合征的表现之一，同时伴有全身多器官或系统的异常。目前已发现82个先天性小眼畸形致病基因，能解释近2/3患者的发病原因。MAB21L1和MAB21L2是高度同源的两个基因，两者的致病变异均可导致小眼畸形，但又各自存在独特的表型特征。本期封面文章报道了MAB21L2基因变异导致小眼畸形2例，并通过回顾文献绘制变异频谱，从变异热点、变异类型、表型特征和基因型-表型相互关系等方面，对MAB21L1和MAB21L2进行比较，为两者缺陷所致眼遗传病的鉴别和诊断提供依据。
先天性小眼畸形是一种罕见的先天性眼球发育异常，表现为眼球体积缩小和结构紊乱，常伴有眼组织缺损，严重影响患者的视觉功能。该病可单独发生，仅影响眼部，也可作为全身综合征的表现之一，同时伴有全身多器官或系统的异常。目前已发现82个先天性小眼畸形致病基因，能解释近2/3患者的发病原因。MAB21L1和MAB21L2是高度同源的两个基因，两者的致病变异均可导致小眼畸形，但又各自存在独特的表型特征。本期封面文章报道了MAB21L2基因变异导致小眼畸形2例，并通过回顾文献绘制变异频谱，从变异热点、变异类型、表型特征和基因型-表型相互关系等方面，对MAB21L1和MAB21L2进行比较，为两者缺陷所致眼遗传病的鉴别和诊断提供依据。
