Clinical Outcomes and Correlation With Biochemical Control in Hydroxocobalamin‐Treated Patients With Early‐Onset Cobalamin C Disease

= 0.2858) levels. This study provides comprehensive, longitudinal biochemical, and clinical follow-up of patients with cblC disease treated from soon after birth, often presymptomatically. Our findings corroborate previous observations regarding the lack of correlation of current biomarkers, both with disease progression and with standard (< 0.3 mg/kg/day) hydroxocobalamin dosing. Further investigation of the clinical impact of early high-dose OHCbl treatment is needed in larger cohorts of patients.