Cobalamin C defect: a patient of late-onset type with homozygous p.R132* mutation.

Methylmalonic aciduria and homocystinuria, cobalamin C (cblC) type, is the most frequent inborn error of vitamin B12metabolism. The clinical phenotype includes systemic symptoms and neurological decompensation. Affected patients can be divided into two broad groups, as early-onset and late-onset.

Hearing loss in biotinidase deficiency: genotype-phenotype correlation.

Children with symptoms of profound biotinidase deficiency with null mutations are more likely to have hearing loss develop than those with missense mutations, even if not treated for a period of time. Hearing loss appears to be preventable in children with null mutations if treatment is initiated soon after birth.