MTHFR and homocystinuria: In conclusion, this study performed extensive gene sequencing analysis with existing biochemical screening and imaging examination in a Chinese family with multiple severe homocystinuria due to MTHFR deficiency cases and found novel compound heterozygous gene variants, c.602 A > C (p.His201Pro) and c.1316T > C (p.Leu439Pro) of the MTHFR gene.