Objectives: Hypocomplementaemic urticarial vasculitis syndrome (HUVS) is a rare and severe form of urticarial vasculitis (UV), and characterised by chronic urticaria, systemic vasculitis, and hypocomplementaemia. Pathogenesis of HUVS is unknown. Genetics may play a role, and DNASE1L3 gene variants were identified in 2 families with HUVS.
Methods: In this study, we conducted a trio-based whole exome sequencing (WES) study to identify new candidate gene(s) in a consanguineous family with an affected son with HUVS, and the identified variant was confirmed by Sanger sequencing. Functional significance of the variant was assessed by bioinformatic tools, including molecular dynamics (MD).
Results: The patient had recurrent episodes of fever, urticarial rash, red eyes, and joint pain from age 13 along with elevated acute phase response, and increased ANA titres over time. WES analysis revealed a nonsense c.769C>T (p.Gln257Ter) variant in the AGBL3 gene, heterozygous in the parents, and homozygous in the index case. The comprehensive MD analyses demonstrated that the Gln257Ter truncation not only eliminates a portion of the protein but also fundamentally alters the structural and dynamic properties of the remaining regions.
Conclusions: Our results indicate that AGBL3 is a novel candidate gene potentially associated with the pathogenesis of HUVS.