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Transcobalamin receptor defect: Identification of two new cases through positive newborn screening for propionic/methylmalonic aciduria and long-term outcome.

Fady Hannah-ShmouniVivian CruzAndreas SchulzeSaadet Mercimek-Mahmutoglu
Published in: American journal of medical genetics. Part A (2018)
Likely pathogenic variants in CD320 cause transcobalamin receptor defect, a recently discovered inborn errors of cobalamin metabolism. Only 12 cases have been reported to date. There are no long-term clinical and biochemical outcome reports since its first description. In this report, we present two new cases and report their long-term treatment outcome. Two asymptomatic cases were identified through a positive newborn screening for propionic/methylmalonic aciduria. Biochemical abnormalities were normalized on a short course of oral cyanocobalamin (1 mg/day). Direct sequencing of CD320 identified a known pathogenic variant (c.262_264GAG; p.Glu88del) confirming the diagnosis of transcobalamin receptor defect. To date, both patients remain asymptomatic with normal neurodevelopment more than 6 years. Our two new cases with transcobalamin receptor defect due to pathogenic variants in CD320 further expand our knowledge and provide a reassuring long-term good neurodevelopmental outcome. Identification of additional cases requires the consideration of transcobalamin receptor defect in the differential diagnosis of newborns with confirmed positive newborn screening for methylmalonic acidurias.
Keyphrases
  • healthcare
  • end stage renal disease
  • pregnant women
  • copy number
  • chronic kidney disease
  • nk cells
  • adverse drug
  • gestational age
  • patient reported outcomes