Central Laboratory, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing Maternal and Child Health Care Hospital, 17 QiHeLou Street, Dongcheng District, Beijing, 100006, China.
Department of Gynecology, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing Maternal and Child Health Care Hospital, 251 YaoJiaYuan Road, Chaoyang District, Beijing, 100026, China.
Biol Res. 2024 Sep 28;57(1):68. doi: 10.1186/s40659-024-00550-w.
Müllerian duct anomalies (MDAs) are congenital developmental disorders that present as a series of abnormalities within the reproductive tracts of females. Genetic factors are linked to MDAs and recent advancements in whole-exome sequencing (WES) provide innovative perspectives in this field. However, relevant mechanism has only been investigated in a restricted manner without clear elucidation of respective observations.
Our previous study reported that 2 of 12 patients with MDAs harbored the CHD1L variant c.348-1G>C. Subsequently, an additional 85 MDAs patients were recruited. Variants in CHD1L were screened through the in-house database of WES performed in the cohort and two cases were identified. One presented with partial septate uterus with left renal agenesis and the other with complete septate uterus, duplicated cervices and longitudinal vaginal septum. The pathogenicity of the discovered variants was further assessed by molecular dynamics simulation and various functional assays.
Ultimately, two novel heterozygous CHD1L variants, including a missense variant c.956G>A (p.R319Q) and a nonsense variant c.1831C>T (p.R611*) were observed. The variants were absent in 100 controls. Altogether, the contribution yield of CHD1L to MDAs was calculated as 4.12% (4/97). All three variants were assessed as pathogenic through various functional analysis. The splice-site variant c.348-1G>C resulted in a 11 bp sequence skipping in exon 4 of CHD1L and led to nonsense mediated decay of its transcripts. Unlike WT CHD1L, the truncated R611* protein mislocalized to the cytoplasm, abolish the ability of CHD1L to promote cell migration and failed to interact with PARP1 owing to the loss of macro domain. The R319Q variant exhibited conformational disparities and showed abnormal protein recruitment behavior through laser microirradiation comparing with the WT CHD1L. All these variants impaired the CHD1L function in DNA damage repair, thus participating in MDAs.
The current study not only expands the mutational spectrum of CHD1L in MDAs but determines three variants as pathogenic according to ACMG guidelines with reliable functional evidence. Additionally, the impairment in DNA damage repair is an underlying mechanism involved in MDAs.
苗勒管发育异常（Müllerian duct anomalies，MDAs）是一种先天性发育障碍，表现为女性生殖道的一系列异常。遗传因素与 MDAs 有关，全外显子组测序（Whole-exome sequencing，WES）的最新进展为此领域提供了新的视角。然而，相关机制仅在有限的范围内进行了研究，未能明确阐述各自的观察结果。
我们之前的研究报告称，在 12 名 MDA 患者中有 2 名携带 CHD1L 变体 c.348-1G>C。随后，又招募了 85 名 MDA 患者。通过对该队列进行的 WES 内部数据库筛选 CHD1L 中的变体，发现了 2 个病例。其中一个表现为部分纵隔子宫伴左侧肾发育不全，另一个表现为完全纵隔子宫、双宫颈和纵向阴道隔。通过分子动力学模拟和各种功能测定进一步评估发现的变体的致病性。
最终，发现了两种新的杂合 CHD1L 变体，包括错义变体 c.956G>A（p.R319Q）和无义变体 c.1831C>T（p.R611*）。这两种变体在 100 名对照中均不存在。总的来说，CHD1L 对 MDA 的贡献率为 4.12%（4/97）。所有三种变体均通过各种功能分析被评估为致病性。剪接位点变体 c.348-1G>C 导致 CHD1L 外显子 4 中 11 个碱基序列缺失，导致其转录物发生无意义介导的衰变。与 WT CHD1L 不同，截断的 R611*蛋白定位到细胞质中，由于宏结构域的缺失，丧失了 CHD1L 促进细胞迁移的能力，并且无法与 PARP1 相互作用。R319Q 变体与 WT CHD1L 相比，通过激光微照射显示出构象差异，并表现出异常的蛋白募集行为。所有这些变体都损害了 CHD1L 在 DNA 损伤修复中的功能，从而参与 MDA 的发生。
本研究不仅扩展了 CHD1L 在 MDA 中的突变谱，还根据 ACMG 指南确定了三种变体具有致病性，并提供了可靠的功能证据。此外，DNA 损伤修复受损是 MDA 发生的潜在机制。
