Late onset thrombosis in two Japanese patients with compound heterozygote protein S deficiency.

•This case report described two patients with compound heterozygote PS deficiency.•In two cases, we identified Ala139Val and c.2135delA mutation in PROS1 gene.•Both proband developed late-onset thrombosis.•Ala139Val mutation might have a mild phenotype.•Qualitative deficiency (Ala139Val) may cause development of late-onset thrombosis.