Next-generation sequencing of 500 POI patients identified novel responsible monogenic and oligogenic variants

Abstract

Background Premature ovarian insufficiency refers to the loss of ovarian function before 40 years of age. The etiology is heterogeneous, and genetic factors account for 20–25% of cases. However, how to transform genetic findings to clinical molecular diagnose remains a challenge. To identify potential causative variations for POI, a next generation sequencing panel with 28 known causative genes of POI was designed, and a large cohort of 500 Chinese Han patients was screened directly. Pathogenic evaluation of the identified variants and the phenotype analysis were performed according to monogenic or oligogenic variants. Results A total of 14.4% (72/500) of the patients carried 61 pathogenic or likely pathogenic variants in 19 of the genes in the panel. Interestingly, 58 variants (95.1%, 58/61) were firstly identified in patients with POI. FOXL2 harbored the highest occurrence frequency (3.2%, 16/500), among whom presented with isolated ovarian insufficiency instead of blepharophimosis-ptosis-epicanthus inversus syndrome. Moreover, luciferase reporter assay confirmed variant p.R349G, which account for 2.6% of POI cases, impaired the transcriptional repressive effect of FOXL2 on CYP17A1. The novel compound heterozygous variants in NOBOX and MSH4 were confirmed by pedigree haplotype analysis, and digenic heterozygous variants in MSH4 and MSH5 were firstly identified. Furthermore, nine patients (1.8%, 9/500) with digenic or multigenic pathogenic variants presented with delayed menarche, early onset of POI and high prevalence of primary amenorrhea compared with those with monogenic variation(s). Conclusions The genetic architecture of POI has been enriched through the targeted gene panel in a large cohort of patients with POI. Specific variants in pleiotropic genes may result in isolated POI rather than syndromic POI, whereas oligogenic defects might have cumulative deleterious effects on the severity of POI phenotype.

Shifting the landscape: Dominant C‐terminal rare missense FOXL2 variants in non‐syndromic primary ovarian failure etiology

“…However, two variants, (p.(Gly187Asp) and p.(Arg349Gly)) have been previously identified in patients with non-syndromic POI. 10,13 To date, all missense variants located in the FOXL2 gene's forkhead domain have been implicated in BPES. However, no clear-cut predictions are possible for missense variants located in the N-terminal and C-terminal region of the protein.…”

“…None of these variants were previously reported in patients with BPES. However, two variants, (p.(Gly187Asp) and p.(Arg349Gly)) have been previously identified in patients with non‐syndromic POI 10,13 . To date, all missense variants located in the FOXL2 gene's forkhead domain have been implicated in BPES.…”

“…Eight studies have reported FOXL2 variants in non‐syndromic POI (Table S1). 6–13 Interestingly, all these variants are located outside of the DNA binding domain, with only a few demonstrating functional effects in vitro 10,11,13 …”

“…Eight studies have reported FOXL2 variants in nonsyndromic POI (Table S1). [6][7][8][9][10][11][12][13] Interestingly, all these variants are located outside of the DNA binding domain, with only a few demonstrating functional effects in vitro. 10,11,13 In this study, we screened the FOXL2 gene in a large cohort of 1282 patients with non-syndromic POI/DOR, identifying 14 variants of FOXL2, including two novel ones.…”

“…[6][7][8][9][10][11][12][13] Interestingly, all these variants are located outside of the DNA binding domain, with only a few demonstrating functional effects in vitro. 10,11,13 In this study, we screened the FOXL2 gene in a large cohort of 1282 patients with non-syndromic POI/DOR, identifying 14 variants of FOXL2, including two novel ones. The aim of the study was to compare the distribution of FOXL2 variants in idiopathic POI/DOR and the two types of BPES, and to ascertain the involvement of FOXL2 in non-syndromic forms of POI.…”