Case report: Novel NUS1 variant in a Chinese patient with tremors and intellectual disability.

Introduction: Nuclear undecaprenyl pyrophosphate synthase 1 (NUS1) gene variants are associated with a range of phenotypes, including epilepsy, intellectual disability, cerebellar ataxia, Parkinson's disease, dystonia, and congenital disorders of glycosylation. Additionally, cases describing genotypes and clinical features are rare.

Case Presentation: Herein, we report the case of a 23-year-old Chinese female patient who presented with tremors, intellectual disability, and epilepsy. A history of carbon monoxide exposure, brain trauma, or encephalitis was not present in this case. Trio whole-exome sequencing analysis revealed a pathogenic variant of c.750del in exon 4, leading to p.Leu251* amino acid substitution. Genetic analysis failed to identify the identical mutations in the remaining family members who underwent screening. The patient was diagnosed with a rare congenital disease, "congenital glycosylation disorder, type 1aa, autosomal dominant, type 55, with seizures (MRD-55)."

Conclusion: We provide further evidence for the role of variants in in the development of tremors, epilepsy, and intellectual disabilities. These findings expand our understanding of the clinical phenotypes of variants.