[Follow up and gene mutation analysis in cases suspected as 3-methylcrotonyl-coenzyme A carboxylase deficiency by neonatal screening].

A certain number of cases with MCCD or suspected as MCCD in this study had no symptoms and normal physical and mental development after follow-up to oldest age of nearly 9 years. The mutation in MCCC1 gene is common, nine novel mutations were found, c.ins1680A may be a hotspot mutation in Chinese population. The urinary GC/MS analysis and blood MS/MS analysis for mother should be routinely performed for all cases with high blood C5-OH level detected by neonatal screening.