Clinical Course of Two Newborns Affected by Cobalamin C Deficiency Diagnosed in the Pre and Post Newborn Screening Era

Cobalamin C deficiency is the best understood and most common phenotype within the group of intracellular cobalamin disorders. The clinical phenotype can range from a disastrous, heterogeneous multisystem disease presenting in the newborn period, to a milder disease with acute or slowly progressive neurological symptoms and behavioural disturbances. Here we report 2 cases of confirmed cobalamin C deficiency. The first case was diagnosed in the pre and the second case in the post newborn screening (NBS) era in Hong Kong. The dramatic difference in the clinical courses of these two patients highlight the importance of early diagnosis and treatment in improving the outcomes of affected individuals through a successfully implemented NBS programme.