Whole-exome sequencing identified two novel mutations of DYNC2LI1 in fetal skeletal ciliopathy.

BACKGROUND

Skeletal ciliopathies are a group of clinically and genetically heterogeneous disorders with the spectrum of severity spanning from relatively mild to prenatally lethal. The aim of our study was to identify pathogenic mutations in a Chinese family with two siblings presenting a Short-rib polydactyly syndrome (SRPS)-like phenotype.

METHOD: Karyotyping and NGS-based CNVseq were performed. Obtaining the negative results in karyotyping and CNVseq, whole-exome sequencing (WES) using genomic DNA (gDNA) extracted from the umbilical cord blood of the first fetus was carried out, followed by bioinformation analysis. The candidate pathogenic variants were confirmed by Sanger sequencing in the family.

RESULTS

No chromosomal abnormalities and pathogenic copy number variations (CNVs) were detected in the affected fetus with SRPS-like phenotype. WES analysis identified two novel compound heterozygous variants in DYNC2LI1, c.358G>T (p.Pro120Ser; NM_001193464), and c.928A>T (p.Lys310Ter; NM_ 001193464). Bioinformatics analysis suggested that c.358G>T (p.Pro120Ser) was likely pathogenic and c.928A>T (p.Lys310Ter) was pathogenic. Sanger sequencing of the two variants in family reveal that c.358G>T was from paternal origin and c.928A>T was from maternal origin, and the second affected fetus had the same compound heterozygous variants in DYNC2LI1. Definitive diagnosis of short-rib thoracic dysplasia 15 with polydactyly (SRTD15) was made in the family.

CONCLUSION

Our results expand the mutational spectrum of DYNC2LI1 in severe skeletal ciliopathies. WES facilitates the accurate prenatal diagnosis of fetal skeletal ciliopathy, and provides helpful information for genetic counseling.