Prenatally and postnatally sequential genetic etiology detection in corpus callosum abnormalities

To evaluate the clinical utility of genetic testing via karyotyping, chromosomal microarray analysis (CMA), and exome sequencing in cases with corpus callosum abnormalities (CCA). Here, 65 prenatal and 12 postnatal cases diagnosed with CCA via ultrasound and magnetic resonance imaging examination were enrolled. All cases were divided into two groups: 21 (27.3%) isolated and 56 (72.7%) non-isolated CCA groups. Karyotyping and CMA were first performed in parallel, then followed by whole exome sequencing (WES) after negative karyotype and CMA results. Clinical outcomes were also followed up. Karyotype abnormalities were identified in 7 cases (9.1%, 7/77). Karyotype abnormality rates in the isolated and non-isolated CCA groups were 8.0% and 9.6%, respectively (p > 0.05). Pathogenic/likely pathogenic (P/LP) CNVs were identified in 11 cases (14.3%, 11/77), including 2(9.5%, 2/21) and 9(16.1%, 9/56) cases in the isolated and non-isolated CCA groups, respectively (p > 0.05). WES identified P/LP diagnostic genetic variants in 8 (47.1%, 8/17) cases, including 2 and 6 cases in the isolated and non-isolated CCA groups, respectively. Additionally, 3 cases with variants of unknown significance were identified. Of the 65 prenatal cases with CCA, 31 (47.7%) were terminated, 1 (1.5%) was a miscarriage, 33 (50.8%) yielded live born babies; of these, 4(12.1%, 4/33) yielded babies with neurodevelopment disorders (NDDs). Of the 12 postnatal cases with CCA, all presented NDDs. Genetic causes of CCA are highly variable. Prenatal brain magnetic resonance imaging and systemic ultrasound examination should be performed to examine other anomalies when CCAs are detected via ultrasound. WES is also recommended following negative karyotype and CMA results.