Ranji Peyman, Pairet Eleonore, Helaers Raphael, Bayet Bénédicte, Gerdom Alexander, Gil-da-Silva-Lopes Vera Lúcia, Revencu Nicole, Vikkula Miikka
Human Molecular Genetics, de Duve Institute, University of Louvain, Brussels, Belgium.
Centre Labio-Palatin, Division of Plastic Surgery, Cliniques universitaires Saint-Luc, University of Louvain, Brussels, Belgium.
Eur J Hum Genet. 2025 Jan;33(1):38-43. doi: 10.1038/s41431-024-01727-3. Epub 2024 Nov 6.
The pathophysiological basis of non-syndromic orofacial cleft (NsOFC) is still largely unclear. However, exome sequencing (ES) has led to identify several causative genes, often with reduced penetrance. Among these, the Rho GTPase activating protein 29 (ARHGAP29) has been previously implicated in 7 families with NsOFC. We investigated a cohort of 224 NsOFCs for which no genetic pathogenic variant had been identified by diagnostic testing. We used ES and bioinformatic variant filtering and identified four novel putative pathogenic variants in ARHGAP29 in four families. One was a missense variant leading to the substitution of the first methionine with threonine, two were heterozygous frameshift variants leading to a premature termination codon, and one was a nonsense variant. All variants were predicted to result in loss of function, either through mRNA decay, truncated ARHGAP29, or abnormal N-terminal initiation of translation of ARHGAP29. The truncated ARHGAP29 proteins would lack the important RhoGAP domain. The variants were either absent or rare in the control population databases, and the loss of intolerance score (pLI) of ARHGAP29 is 1.0, suggesting that ARHGAP29 haploinsufficiency is not tolerated. Phenotypes ranged from microform cleft lip (CL) to complete bilateral cleft lip and palate (CLP), with one unaffected mutation carrier. These results extend the mutational spectrum of ARHGAP29 and show that it is an important gene underlying variable NsOFC phenotypes. ARHGAP29 should be included in diagnostic genetic testing for NsOFC, especially familial cases, as it may be mutated in ∼4% of them (4/97 in our cohort) with high penetrance (89%).
非综合征性口面部裂隙(NsOFC)的病理生理基础仍不清楚。然而,外显子组测序(ES)已鉴定出多个致病基因,其外显率通常较低。其中,Rho GTP酶激活蛋白29(ARHGAP29)此前已在7个NsOFC家族中被发现有牵连。我们对224例NsOFC患者进行了研究,这些患者经诊断性检测未发现遗传致病变异。我们采用ES和生物信息学变异筛选方法,在4个家族的ARHGAP29基因中鉴定出4个新的推定致病变异。一个是错义变异,导致第一个甲硫氨酸被苏氨酸替代;两个是杂合移码变异,导致提前出现终止密码子;另一个是无义变异。所有变异预计都会导致功能丧失,其机制可能是通过mRNA降解、截短的ARHGAP29蛋白或ARHGAP29翻译的异常N端起始。截短的ARHGAP29蛋白将缺乏重要的RhoGAP结构域。这些变异在对照人群数据库中不存在或罕见,且ARHGAP29的不耐受性丧失评分(pLI)为1.0,表明ARHGAP29单倍体不足是无法耐受的。其表型范围从微小型唇裂(CL)到完全性双侧唇腭裂(CLP),其中有一名未受影响的突变携带者。这些结果扩展了ARHGAP29的突变谱,表明它是导致NsOFC表型变异的一个重要基因。ARHGAP29应纳入NsOFC的诊断性基因检测,尤其是家族性病例,因为在约4%的患者中(我们队列中的97例中有4例)它可能发生高外显率(89%)的突变。
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