ALG13 X-linked intellectual disability: New variants, glycosylation analysis, and expanded phenotypes

Hind Alsharhan, Miao He, Andrew C. Edmondson, Earnest J.P. Daniel, Jie Chen, Tyhiesia Donald, Somayeh Bakhtiari, David J. Amor, Elizabeth A. Jones, Grace Vassallo, Marie Vincent, Benjamin Cogné, Wallid Deb, Arend H. Werners, Sheng C. Jin, Kaya Bilguvar, John Christodoulou, Richard I. Webster, Katherine R. Yearwood, Bobby G. NgHudson H. Freeze, Michael C. Kruer, Dong Li, Kimiyo M. Raymond, Elizabeth J. Bhoj, Andrew K. Sobering

Research output: Contribution to journalArticlepeer-review

Abstract

Pathogenic variants in ALG13 (ALG13 UDP-N-acetylglucosaminyltransferase subunit) cause an X-linked congenital disorder of glycosylation (ALG13-CDG) where individuals have variable clinical phenotypes that include developmental delay, intellectual disability, infantile spasms, and epileptic encephalopathy. Girls with a recurrent de novo c.3013C>T; p.(Asn107Ser) variant have normal transferrin glycosylation. Using a highly sensitive, semi-quantitative flow injection-electrospray ionization-quadrupole time-of-flight mass spectrometry (ESI-QTOF/MS) N-glycan assay, we report subtle abnormalities in N-glycans that normally account for <0.3% of the total plasma glycans that may increase up to 0.5% in females with the p.(Asn107Ser) variant. Among our 11 unrelated ALG13-CDG individuals, one male had abnormal serum transferrin glycosylation. We describe seven previously unreported subjects including three novel variants in ALG13 and report a milder neurodevelopmental course. We also summarize the molecular, biochemical, and clinical data for the 53 previously reported ALG13-CDG individuals. We provide evidence that ALG13 pathogenic variants may mildly alter N-linked protein glycosylation in both female and male subjects, but the underlying mechanism remains unclear.

Original languageEnglish
Pages (from-to)1001-1012
Number of pages12
JournalJournal of Inherited Metabolic Disease
Volume44
Issue number4
DOIs
StatePublished - Jul 2021

Keywords

  • N-glycans
  • carbohydrate deficient transferrin
  • congenital disorders of glycosylation
  • epilepsy
  • exome sequencing
  • mass spectrometry

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