Missense variants affecting the actin-binding domains of PLS3 cause X-linked congenital diaphragmatic hernia and body wall defects

Abstract

Congenital diaphragmatic hernia (CDH) is a relatively common and genetically heterogeneous structural birth defect associated with high mortality and morbidity. We describe eight unrelated families with a novel X-linked condition characterized by diaphragm defects, variable anterior body wall anomalies, and/or facial dysmorphism. Using linkage analysis and whole exome or whole genome sequencing, we identified novel missense variants in the actin binding domains of plastin 3 (PLS3), a gene encoding an actin bundling protein, that co-segregate with disease in all families. Loss-of-function variants in PLS3 have been described previously in association with X-linked osteoporosis. To address these seemingly disparate clinical phenotypes, we performed in silico protein modeling and cellular overexpression experiments, which suggest that the affected residues in individuals with CDH are important for actin binding and result in disorganization of the actin cytoskeleton and a reduction in normal actin stress fiber formation. A mouse knock-in model of a variant identified in one of the families, p.W499C, shows partial perinatal lethality and recapitulates the key findings of the human phenotype, including diaphragm and abdominal wall defects. Both the mouse model and one surviving adult patient with a PLS3 variant were observed to have increased, rather than decreased, bone mineral density. Together, these clinical and functional data in human and mouse reveal that specific missense variants affecting the actin binding domains of PLS3 may have a gain-of-function effect and cause a new Mendelian disorder.

Genetically Modified Mouse Models of Congenital Diaphragmatic Hernia: Opportunities and Limitations for Studying Altered Lung Development

“…A novel missense variant affecting the actin-binding domains of plastin 3 (PLS3) was recently identified in eight unrelated families, causing X-linked CDH and body wall defects. A genetically modified mouse model of this Pls3 W499C variant resulted in perinatal death and reproduced the main features of the human phenotype, including diaphragmatic and body wall abnormalities (124). An abnormal plastin-actin interaction is the most likely explanation for the observed congenital malformation in both humans and mice.…”

Actin Bundles Dynamics and Architecture

“…Its deletions and several missense or short insertion mutations (without frame shift) are linked to congenital osteoporosis, likely due to the anomalous (reduced or elevated) sensitivity to Ca 2+ of the respective mutant proteins [ 68 ]. A separate set of mutations results in a severe congenital diaphragmatic hernia (CDH) [ 157 ]. While the effects of CDH mutations have not been biochemically characterized, they may be related to the role of T-plastin as a regulator of basement membrane assembly and epidermal morphogenesis [ 158 ].…”