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Merck
  • Positive newborn screen for methylmalonic aciduria identifies the first mutation in TCblR/CD320, the gene for cellular uptake of transcobalamin-bound vitamin B(12).

Positive newborn screen for methylmalonic aciduria identifies the first mutation in TCblR/CD320, the gene for cellular uptake of transcobalamin-bound vitamin B(12).

Human mutation (2010-06-05)
Edward V Quadros, Shao-Chiang Lai, Yasumi Nakayama, Jeffrey M Sequeira, Luciana Hannibal, Sihe Wang, Donald W Jacobsen, Sergey Fedosov, Erica Wright, Renata C Gallagher, Natascia Anastasio, David Watkins, David S Rosenblatt
PMID20524213
ABSTRACT

Elevated methylmalonic acid in five asymptomatic newborns whose fibroblasts showed decreased uptake of transcobalamin-bound cobalamin (holo-TC), suggested a defect in the cellular uptake of cobalamin. Analysis of TCblR/CD320, the gene for the receptor for cellular uptake of holo-TC, identified a homozygous single codon deletion, c.262_264GAG (p.E88del), resulting in the loss of a glutamic acid residue in the low-density lipoprotein receptor type A-like domain. Inserting the codon by site-directed mutagenesis fully restored TCblR function.