Prenatal diagnosis of a fetus with agenesis of the corpus callosum and congenital heart disease due to a non-frameshift deletion variant in SMARCA4
Agenesis of the corpus callosum (ACC) is a birth defect with an incidence of 0.020–0.025% in live births, and is often accompanied by anomalies in the cardiovascular and the musculoskeletal system. ACC is a core phenotype in many syndromes, such as Coffin-Siris syndrome (CSS) whose prominent characteristics include structural central nervous system abnormalities, intellectual disability, facial features, hypertrichosis, visual/hearing impairment, hypotonia, distal hypoplasia, congenital heart disease. SMARCA4, a SWItch/Sucrose non-fermentable complex gene, is considered as a causative gene of CSS. We diagnosed a fetus with ACC, Dandy-Walker malformation, complete atrioventricular septal defect, single umbilical artery, and bilateral rocker-bottom feet during prenatal diagnosis. Through karyotype analysis, chromosomal microarray analysis, and whole-exome sequencing, we detected a novel in-frame variant in SMARCA4 (NM_001128849.3: c.3439_3450del, p.S1147_F1150del) in the fetus and made a diagnosis of CSS.We identified the genetic etiology of ACC in the fetus. Our finding enrich the spectrum of SMARCA4 variants, contribute to further understanding of the phenotype of CSS, and show the significance of genetic screening in prenatal diagnosis.