High prevalence of structural heart disease in children with cblC-type methylmalonic aciduria and homocystinuria.

[homocystinuria without methylmalonic aciduria]

To characterize the frequency and nature of cardiovascular defects in patients with CblC-type methylmalonic aciduria and homocystinuria (cblC ), an inborn error of cobalamin (vitamin B 12 ) metabolism resulting in accumulation of methylmalonic acid and homocysteine .A retrospective observational study was conducted investigating 10 patients with cblC ranging in age from 2 weeks to 24 years (mean 4 .4 years +/- 7 .5 years , median 0 .6 years ). All patients underwent a complete 2 -D echocardiogram including quantitative assessment of left ventricular systolic function .Structural heart defects were detected in 50 % of patients with cblC . Heart defects included left ventricular (LV ) non-compaction (3 ), secundum atrial septal defect (2 ), muscular ventricular septal defect (1 ), dysplastic pulmonary valve without pulmonary stenosis (1 ) and mitral valve prolapse with mild mitral regurgitation (1 ). One patient had resolved cor pulmonale and right heart failure secondary to pulmonary embolism . All patients had quantitatively normal LV systolic function .Diverse and clinically significant structural heart defects appear to be highly prevalent in cblC , perhaps due to abnormal DNA and histone methylation during embryogenesis . The specific cardiac defects detected in our cohort were variable , and studies with a larger number of patients are needed to establish which forms are most common . Routine and periodic cardiovascular evaluation may be indicated in patients with cblC .