Whole genome sequencing identified two novel compound heterozygous RYR1 mutations causing fetal akinesia deformation sequence in cases where whole exome sequencing was negative, enabling genetic diagnosis in 100% of affected fetuses studied.
Does whole genome sequencing identify pathogenic variants in cases of fetal akinesia deformation sequence with negative whole exome sequencing?
Whole genome sequencing is effective in diagnosing fetal anomalies like FADS by identifying non-coding and structural variants missed by whole exome sequencing.
Estimación del efecto: diagnostic yield increase
Tasa de eventos absoluta: 100% vs 0%
Introduction: Fetal akinesia deformation sequence (FADS), a severe prenatal phenotype associated with congenital myopathies (CMs), is linked to mutations in the RYR1 gene. Although whole exome sequencing (WES) is a standard diagnostic approach, certain pathogenic variants may remain undetected. In this study, we utilized whole genome sequencing (WGS) to investigate a recurrent case of FADS with negative WES results. Methods: A couple who experienced four consecutive pregnancy losses, including two fetuses affected by FADS, underwent trio-WGS following negative WES findings. Variants were annotated using public databases and filtered according to ACMG guidelines. Functional validation of an intronic variant was conducted using RT-PCR, TA cloning, and Sanger sequencing. Results: WGS identified two novel RYR1 compound heterozygous variants in the affected fetus: a paternally inherited in-frame deletion (c. 13659+655₁4172+588delinsCTGGCGCCCCATCTCAT) located the C-terminal hotspot, and a maternally inherited deep intronic variant (c. 4934+25G>A). Both of them were initially classified as variant of uncertain significance (VUS). RNA studies demonstrated that this intronic variant caused a 26-bp intron retention and frameshift, leading to its reclassification as pathogenic. And according to this PM3 evidence, the in-frame deletion was reclassified as likely pathogenic. Both variants were absent from population databases and exhibited segregation with the phenotype. Conclusion: This study highlights the utility of WGS in diagnosing fetal anomalies with negative WES results by identifying non-coding and structural variants. The identification of novel RYR1 mutations broadens the genetic spectrum of recessive CMs and emphasizes the necessity for functional assays to accurately interpret intronic variants. WGS is recommended for cases of recurrent fetal anomalies when WES is inconclusive, although careful interpretation of variants is advised.
Wang et al. (Mon,) conducted a other in Early-onset Fetal Akinesia Deformation Sequence (FADS) linked to RYR1 mutations (n=2). Whole genome sequencing (WGS) vs. Whole exome sequencing (WES) was evaluated on Identification of pathogenic genetic variants causing FADS (diagnostic yield increase). Whole genome sequencing identified two novel compound heterozygous RYR1 mutations causing fetal akinesia deformation sequence in cases where whole exome sequencing was negative, enabling genetic diagnosis in 100% of affected fetuses studied.