Copy number variants and placental abnormalities in stillborn fetuses

Abstract

Objective To examine the association of fetal/placental DNA copy number variants (CNVs) with pathologic placental lesions (PPLs) in pregnancies complicated by stillbirth. Design A secondary analysis of stillbirth cases in the Stillbirth Collaborative Research Network case-control study. Setting Multicenter, 59 hospitals in five geographical regions in the USA. Population 387 stillbirth cases (2006-2008). Methods Using standard definitions, PPLs were categorised by type including maternal vascular, fetal vascular, inflammatory and immune/idiopathic lesions. Single-nucleotide polymorphism array detected CNVs of at least 500 kb. CNVs were classified into two groups: normal, defined as no CNV >500 kb or benign CNVs, and abnormal, defined as pathogenic or variants of unknown clinical significance. Main outcome measures The proportions of abnormal CNVs and normal CNVs compared between stillbirth cases with and without PPLs using the Wald Chi-square test. Results Of 387 stillborn fetuses, 327 (84.5%) had maternal vascular PPLs and 60 (15.6%) had abnormal CNVs. Maternal vascular PPLs were more common in stillborn fetuses with abnormal CNVs than in those with normal CNVs (81.7% versus 64.2%; P = 0.008). The proportions of fetal vascular, maternal/fetal inflammatory and immune/idiopathic PPLs were similar among stillborn fetuses with abnormal CNVs and those with normal CNVs. Pathogenic CNVs in stillborn fetuses with maternal vascular PPLs spanned several known genes. Conclusions Abnormal placental/fetal CNVs were associated with maternal vascular PPLs in stillbirth cases. The findings may provide insight into the mechanisms of specific genetic abnormalities associated with placental dysfunction and stillbirth.