Objective To conduct a feasibility whole-genome sequencing (WGS) study
in families to identify genetic variants relevant to unexplained
pregnancy loss. Methods We conducted a pilot WGS study of four families
with recurrent pregnancy loss, including parents, healthy live births,
and losses, which included an embryonic loss (<10 weeks’
gestation), fetal deaths (10-20 weeks’ gestation) and stillbirths (≥ 20
weeks’ gestation). We used the Illumina platform for WGS and
state-of-the-art protocols to identify single nucleotide variants (SNVs)
following various modes of inheritance. Results We identified 87 SNVs
involving 75 genes in embryonic loss (n=1), 370 SNVs involving 228 genes
in fetal death (n=3), and 122 SNVs involving 122 genes in stillbirth
(n=2). Of these, 22 de novo, 6 autosomal dominant and an X-linked
recessive SNVs were pathogenic (probability of being loss-of-function
intolerant >0.9), impacting known genes (e.g., DICER1,
FBN2, FLT4, HERC1, and TAOK1) involved in embryonic/fetal development
and congenital abnormalities. Further, we identified missense compound
heterozygous SNVs impacting genes (e.g., VWA5B2) in two fetal death
samples that were absent from live births and population controls,
providing evidence for haplosufficient genes relevant to pregnancy loss.
Conclusions In this pilot study, we provide evidence for de novo and
inherited SNVs relevant to pregnancy loss. Our findings provide
justification for conducting WGS using larger numbers of families and
warrant validation by targeted sequencing to ascertain causal variants.
Elucidating genes causing pregnancy loss may facilitate the development
of risk stratification strategies and novel therapeutics.