P-522 Custom design gene panel as a diagnostic for human non-syndromic infertility
Authors: Okutman O , Tarabeux J , Muller J , Viville S 
Published: June 2022

Abstract

Study question
What is the relevance to offer panels of infertility genes as a diagnostic tool for infertile patients?

Summary answer
Our results demonstrate the interest of custom designed panel to define the genetic etiology of infertile couple in up to 26% of cases.

What is known already
The etiology of infertility is very heterogeneous, and due to the complexity of the reproductive process, standard fertility examinations fail to identify an etiology in 15 to 30% of infertile couples. It is believed that about half of these cases could be explained by a genetic defect. Until recently, routine genetic tests in the field of infertility were restricted to karyotyping, Yq microdeletion, CFTR mutation screening and FMR1 gene screening. The improvement of high throughput sequencing (HTS) technologies has considerably modified the discovery of the genetic causes of diseases allowing the development of new genetic diagnostic tools.

Study design, size, duration
Since 2016, we have set up, within the genetic diagnostic service of the Strasbourg University Hospital (HUS), a gene panel assay of preselected genes for the genetic diagnosis of male and female non-syndromic infertility. Since 2016, reflecting the high level of the research in this field, we have upgraded our panel two times. Initially, our panel included 16 infertility genes, then 51. We are now offering a panel of 133 infertility genes.

Participants/materials, setting, methods
Three different infertility gene panels were used to analyse 205 infertile cases; 62 females and 143 males. Agilent-SureSelectQXT Target Enrichment system was used to prepare libraries from genomic DNA. Sequencing was performed on Illumina NextSeq 550 with 2x150bp reads. Variant analysis was achieved using VaRank tool. One control DNA with known genotype was used in the first run of each design for the quality control. Identity of each patient was confirmed by independent Taqman technology.

Main results and the role of chance
Our first custom designed infertility panel (V1) contained 16 genes; one female and 11 male samples were tested, one positive male sample was identified and resulted in a diagnostic yield of 8.3% (1/12). The second version of the panel (V2), encompassed 51 genes, 22 female and 91 male samples were analysed, allowing a diagnostic yield of 6.1% [7/113; diagnostic rate for female was 9% (2/22), diagnostic rate for male was 5.5% (5/91)]. The third version of our panel (V3) contains 133 infertility genes and so far the diagnostic yield is 26.3% (21/80). Among 80 samples analysed, 39 of them were female for whom we got a diagnostic rate of 17.9% (7/39) and 41 were male for whom we got a diagnostic rate of 34.1% (14/41). Concerning V2 panel, we analysed 69 azoospermic patients for whom the diagnosis was only based on semen analysis and we identified only 2 pathogenic variants (2.8%, 2/69). For the V3 panel, the analysis of 30 azoospermic samples among which 26 diagnosed via testicular biopsy and pathology report, leaded to a diagnostic yield of 33.3% (10/30). These results underline the importance of well-defined clinical data in the field of genetics of infertility.

Limitations, reasons for caution
The main limitation is the number of patients’ analysed so far. In order to fully challenge the clinical interest of such diagnostic tool, a larger group of patients needs to be analysed.

Wider implications of the findings
The precise molecular diagnostic is important for adapting the best treatment and counsel not only to patients but to their spouse and relatives. This study allows us to decipher the prevalence of mutations in identified genes for a specific infertility phenotype on our cohort of infertile patients.

Trial registration number
not applicable