Identification and functional analysis of biallelic loss-of-function variants of WNT7B in a Chinese family affected with PDAC syndrome.

WNT7B-related pulmonary hypoplasia, diaphragmatic anomalies, anophthalmia/microphthalmia, and cardiac defects (PDAC) syndrome is rarely reported. To date, only two each nonsense and missense variants of WNT7B were identified in five pedigrees affected with a PDAC spectrum from two independent studies. Additionally, the gene-disease association between WNT7B and PDAC syndrome is not yet clarified in OMIM database. Here, the whole exome sequencing was used to identify biallelic novel loss-of-function (LoF) variants c.324C > G (p.Tyr108*) and c.668_669dup (p.Val224Argfs*6) of WNT7B in a fetus affected with a typical PDAC spectrum, including pulmonary hypoplasia/agenesis, bilateral microphthalmia, and absence of pulmonary arteries and veins, from a Chinese family. Subsequent functional analysis revealed that the two LoF variants decreased the RNA and protein expression levels of WNT7B, and significantly impaired the canonical WNT-β-Catenin signaling pathway, which is essential for regulation of human lung development. We broaden the variant spectrum of WNT7B, and provide genetic and experimental evidence to confirm the association between WNT7B pathogenic variants and PDAC spectrum.