Pathogenicity effects of a COL2A1 missense mutation (c.1594G>C) in cartilage development.

The COL2A1 gene encodes the α1 chain of type II collagen, a critical structural component in cartilage and the extracellular matrix. Mutations in this gene are associated with type II collagenopathies, including achondrogenesis type II (ACG2), a severe skeletal dysplasia characterized by perinatal lethality. This study aims to identify and characterize the molecular basis of a COL2A1 mutation in a patient presenting with ACG2 features and to elucidate the pathogenic mechanism of the mutation. A newborn with clinical signs of ACG2 underwent whole-exome sequencing (WES) for genetic analysis. Structural modeling was performed using AlphaFold2 to assess the mutation's impact on the collagen triple-helix. Functional studies were conducted using HEK-293 and C28/I2 cells transfected with wild-type or mutant COL2A1 to evaluate collagen synthesis and secretion via immunoblotting and ELISA. WES identified a heterozygous missense mutation in COL2A1 gene (NM_001844.5: c.1584G>C, p.Glu532Gln). Structural modeling predicted that the mutation disrupted the stability of the triple-helix. Functional assays demonstrated increased synthesis and impaired secretion of type II collagen in cells expressing the mutant COL2A1 gene. The identified COL2A1 mutation (p.Glu532Gln) may lead to disrupted collagen structure and secretion, contributing to the pathogenesis of ACG2. These findings advance the understanding of COL2A1-related disorders and highlight the molecular mechanisms underlying type II collagenopathies.