Over 75 MMACHC mutations have been detected in cblC diseases [1, 2, 14], among which c.271dupA and c.331C > T are the most common for early-onset cblC and c.394C > T was associated mainly with the late-onset subtype [13, 15–18]. Here, MMACHC is linked to methylmalonic aciduria and homocystinuria type cblC.