1. ALG13 X-linked intellectual disability: New variants, glycosylation analysis, and expanded phenotypes
- Author
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Alsharhan, H, He, M, Edmondson, AC, Daniel, EJP, Chen, J, Donald, T, Bakhtiari, S, Amor, DJ, Jones, EA, Vassallo, G, Vincent, M, Cogne, B, Deb, W, Werners, AH, Jin, SC, Bilguvar, K, Christodoulou, J, Webster, RI, Yearwood, KR, Ng, BG, Freeze, HH, Kruer, MC, Li, D, Raymond, KM, Bhoj, EJ, Sobering, AK, Alsharhan, H, He, M, Edmondson, AC, Daniel, EJP, Chen, J, Donald, T, Bakhtiari, S, Amor, DJ, Jones, EA, Vassallo, G, Vincent, M, Cogne, B, Deb, W, Werners, AH, Jin, SC, Bilguvar, K, Christodoulou, J, Webster, RI, Yearwood, KR, Ng, BG, Freeze, HH, Kruer, MC, Li, D, Raymond, KM, Bhoj, EJ, and Sobering, AK
- 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.
- Published
- 2021