Rare missense variant in MSH4 associated with primary gonadal failure in both 46, XX and 46, XY individuals
Rare missense variant in MSH4 associated with primary gonadal failure in both 46, XX and 46, XY individuals
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DOI：
10.1093/humrep/deaa362
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发表时间：
2021-01-15
影响因子：
6.1
通讯作者：
Totonchi, Mehdi
中科院分区：
文献类型：
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作者：
Akbari, Arvand;Padidar, Kimiya;Totonchi, Mehdi
研究问题：全外显子组测序（WES）能否揭示一个近亲家庭中男性和女性患者原发性性腺功能衰竭的共同致病变异？简要答复：原发性卵巢功能不全（P01）和非梗阻性无精子症（NOA）患者的罕见错义变体p.S754L是纯合子，该突变体位于ATP酶结构域高度保守的MSH 4 MutS特征基序中。已知：MSH 4是一种减数分裂特异性蛋白，在睾丸和卵巢中以一定水平表达。沿着其异源二聚体配偶体MSH 5，负责双链霍利迪连接识别和稳定，以确保减数分裂期间染色体的准确分离。据报道，Msh 4和MshS的敲除雄性和雌性小鼠由于减数分裂停滞而不育。在人类中，MSH 4与男性和女性性腺衰竭相关，在MutS结构域V中具有不同的变化。研究设计、大小、持续时间：这是一项对一个在两种性别中都有多例性腺衰竭的血缘家族的回顾性遗传学研究。对象/材料、地点、方法：对POI先证者、NOA患者的一个兄弟、一个有生育能力的姐妹及其父母进行WES。发现的变异在这些个体中得到了验证，该家族的其他成员也通过桑格测序进行了基因分型。该变异体在Iranome数据库中的800名伊朗健康个体中未检测到，在30名散发性NOA和30名散发性PO 1患者中也未检测到。通过RT-PCR研究了异常剪接中的暗示效应。此外，蛋白质同源性建模被用来进一步调查的氨基酸取代silico.Main结果和机会的作用：发现的变体是非常罕见的，从来没有报道过在纯合状态。它发生在ATP酶结构域的丝氨酸754处，这是高度保守的MutS特征基序内的第一个残基，用亮氨酸取代它。所有变体效应预测工具均表明该变体有害。由于置换发生在第755位的步行者B基序之前，因此进行了基于蛋白质同源性的进一步研究。考虑到建模结果，取代的氨基酸残基的性质和p.S754L变异与步行者B基序的残基之间的距离表明影响蛋白质的ATP酶活性的构象变化的可能性。我们已分别根据SCV 001169709、SCV 001169708和SCV 001142647向ClinVar提交了少精症、NOA和PO 1的dbSNP条目rs377712900。限制、排除原因：在模式生物的研究，可以揭示更多的光的作用，这种变异，因为我们的结果是通过变异效应预测工具和蛋白质同源modeling.WIDER的影响的发现：鉴定减数分裂基因的变异应提高遗传咨询男性和女性不育。此外，由于我们的两名NOA患者接受了睾丸精子提取（TESE），但没有成功，因此在TESE之前排除此类患者减数分裂基因中存在致病性变异可能是有用的。
STUDY QUESTION: Can whole-exome sequencing (WES) reveal a shared pathogenic variant responsible for primary gonadal failure in both male and female patients from a consanguineous family?SUMMARY ANSWER: Patients with primary ovarian insufficiency (P01) and non-obstructive azoospermia (NOA) were homozygous for the rare missense variant p. S754L located in the highly conserved MSH4 MutS signature motif of the ATPase domain. An oligozoospermic patient was heterozygous for the variant.WHAT IS KNOWN ALREADY: MSH4 is a meiosis-specific protein expressed at a certain level in the testes and ovaries. Along with its heterodimer partner MSH5, it is responsible for double-strand Holliday junction recognition and stabilization, to ensure accurate chromosome segregation during meiosis. Knockout male and female mice for Msh4 and MshS are reportedly infertile due to meiotic arrest. In humans, MSH4 is associated with male and female gonadal failure, with distinct variations in the MutS domain V.STUDY DESIGN, SIZE, DURATION: This was a retrospective genetics study of a consanguineous family with multiple cases of gonadal failure in both genders. The subject family was recruited in Iran, in 2018.PARTICIPANTS/MATERIALS, SETTING, METHODS: The proband who is affected by POI, an NOA brother, a fertile sister and their parents were subjected to WES. The discovered variant was validated in these individuals, and the rest of the family was also genotyped by Sanger sequencing. The variant was not detected in 800 healthy Iranian individuals from the lranome database nor in 30 sporadic NOA and 30 sporadic PO1 patients. Suggested effect in aberrant splicing was studied by RT-PCR. Moreover, protein homology modeling was used to further investigate the amino acid substitution in silico.MAIN RESULTS AND THE ROLE OF CHANCE: The discovered variant is very rare and has never been reported in the homozygous state. It occurs in the ATPase domain at Serine 754, the first residue within the highly conserved MutS signature motif, substituting it with a Leucine. All variant effect prediction tools indicated this variant as deleterious. Since the substitution occurs immediately before the Walker B motif at position 755, further investigations based on protein homology were conducted. Considering the modeling results, the nature of the substituted amino acid residue and the distances between p. S754L variation and the residues of the Walker B motif suggested the possibility of conformational changes affecting the ATPase activity of the protein.LARGE SCALE DATA: We have submitted dbSNP entry rs377712900 to ClinVar under SCV001169709, SCV001169708 and SCV001142647 for oligozoospermia, NOA and PO1, respectively.LIMITATIONS, REASONS FOR CAUTION: Studies in model organisms can shed more light on the role of this variant as our results were obtained by variant effect prediction tools and protein homology modeling.WIDER IMPLICATIONS OF THE FINDINGS: Identification of variants in meiotic genes should improve genetic counseling for both male and female infertility. Also, as two of our NOA patients underwent testicular sperm extraction (TESE) with no success, ruling out the existence of pathogenic variants in meiotic genes in such patients prior to TESE could prove useful.