# Pilot Study of Preconception Carrier Screening in Russia: Initial Findings and Challenges

## TL;DR

This Russian pilot study shows that preconception genetic screening can identify couples at high risk of having children with genetic disorders.

## Contribution

The study introduces the first preconception carrier screening in Russia using a 33-gene panel and highlights unique challenges and findings.

## Key findings

- 35.8% of women were carriers of at least one pathogenic variant.
- Six couples (3.6% of the cohort) were identified as high risk for genetic disorders.
- Frequencies of gene variants differed from theoretical expectations.

## Abstract

Background/Objectives: This study reports on findings from the first preconception screening performed in Russia and provides a comprehensive discussion of the significant results and challenges faced during the implementation of the project. Methods: Using a targeted sequencing panel of 33 genes (associated with 29 autosomal recessive and 4 X-linked diseases), we analyzed 165 couples considering pregnancy. The screening design also included analysis of the frequent pathogenic variants in the SMN1, DMD, CFTR, and CYP21A2 genes that may not be detected through the next-generation sequencing approach. The sequential screening protocol, wherein the female partner was tested first, was used. Results: The results revealed that 35.8% of women (n = 59) were carriers of at least one pathogenic or likely pathogenic (P/LP) variant, with 7.9% of women (n = 13) carrying variants in two or more genes. Notably, the analysis identified 5 deletions of exon 7 in the SMN1 gene, 1 deletion of the CYP21A2 gene, and 1 large duplication in the DMD gene in female participants. The most frequently identified pathogenic variants occurred in the CYP21A2, GJB2, SERPINA1, and ATP7B genes. The screening identified six couples (3.6% of the cohort) at high risk of having a child with an autosomal recessive or X-linked genetic disorder. Conclusions: This pilot study confirms the high clinical utility of the gene panel, effectively evaluating reproductive risk in couples without a known family history of monogenic diseases. The findings indicate that the observed frequencies of identified gene variants differ from those theoretically expected, with a notable percentage of identified couples being at relatively high risk. Furthermore, these results highlight the indispensable role of comprehensive genetic counseling both before and after testing to ensure an appropriate preconception testing algorithm and informed reproductive decision-making.