Recurrent Venous Thrombosis in an Adolescent Male with CBS Mutation and Persistent Antiphospholipid Antibody Positivity: A Case Report

Homocysteine (Hcy) contributes to endothelial dysfunction and impaired thrombolysis, and genetic polymorphisms that elevate plasma Hcy concentrations have been linked to an increased risk of thrombosis. Notably, mutations in the cystathionine β-synthase (CBS) gene, which reduce enzymatic activity, are a well-established cause of hyperhomocysteinemia (HHcy). This case report presents a 15-year-old male with recurrent, severe deep vein thrombosis (DVT) of the lower extremities, accompanied by persistent positivity for antiphospholipid antibodies. Laboratory evaluation revealed elevated homocysteine levels and mutations in the CBS gene, highlighting an underlying genetic predisposition. The persistent presence of antiphospholipid antibodies further underscores the multifactorial nature of his thrombophilic condition, involving genetic, metabolic, and autoimmune mechanisms.