Özgün, NezirŞahin, Yavuz2021-11-262021-11-262022Özgün, N., & Şahin, Y. (2021). A case with congenital disorder of glycosylation with defective fucosylation 2 and new mutation in FUK gene. Brain & development, S0387-7604(21)00206-0. Advance online publication.https://doi.org/10.1016/j.braindev.2021.11.001https://hdl.handle.net/20.500.12713/2280Introduction: Congenital disorders of glycosylation (CDG) is a group of rare, hereditary, multisystem disorders, predominantly affecting nervous system. There are N- and O- types of glycosylation. Fucosylation, a form of N-glycosylation, involves many enzymes. Until today, type 1 and type 2 fucosylation defects were identified, having pathogenic variants in genes encoding ?-1,6-fucosyltransferase and fucokinase enzymes, respectively. In this article, a patient with type 2 fucosylation defect will be presented, with hypotonia, developmental delay and blindness and a pathogenic variant that was previously described in two patients. Method: Whole exome sequencing (WES) was performed, since the patient had no time to implement diagnostic algorithm for hypotonia etiology. Results: WES revealed a new pathogenic variant of homozygous c.993_1011del (p.Glu335Hisfs*55) frameshift variant of the FUK gene NM_145059 transcript. She had milder clinical manifestation than reported two patients. Conclusion: Congenital Defect of Glycosylation should be considered when the clinical findings cannot be explained by other known diseases, particularly in patients with multisystemic, predominantly neurological involvement.eninfo:eu-repo/semantics/closedAccessCongenital Defect of GlycosylationDevelopmental DelayHypotoniaType2 Fucosylation DefectArticle34802815WOS:0007524324000082-s2.0-85119433418Q310.1016/j.braindev.2021.11.001N/A