CblC disease is caused by recessive pathogenic variants in the MMACHC gene (Gene ID: 25974; OMIM *609831, location: 1p34.1) [11] in which 115 disease-causing variants have been reported so far (http://www.biobase-international.com/product/hgmd), some of them clustering according to ethnicity [12]. The gene discussed is MMACHC; the disease is methylmalonic aciduria and homocystinuria type cblC.