Analysis of a child with neurodevelopmental disorders due to variant of HNRNPU gene and a literature review

Abstract

To explore the clinical characteristics and genetic variant in a child with neurodevelopmental disorders (NDDs). Clinical data of a child who had presented at Xiaogan Hospital Affiliated to Wuhan University of Science and Technology in December 2020 due to intermittent convulsions for over a year were retrospectively analyzed. Peripheral blood samples of the child and his parents were collected and subjected to whole exome sequencing. Candidate variants were verified by Sanger sequencing and bioinformatic analysis. "HNRNPU gene", "epilepsy", "epileptic encephalopathy", "hereditary epilepsy", "neurodevelopmental disorder", "neurodevelopmental syndrome", "HNRNPU", and "NDDs" were used as the key words to search the CNKI, Wanfang and PubMed databases dated from January 1, 1994 to February 10, 2022. The patient was a 2-year-old boy who had developed seizure at the age of 5 months. His clinical features had included abnormal appearance, recurrent seizures, and low developmental quotients of each functional area as evaluated by the Gesell scale. The child was given sodium valproate for the antiepileptic treatment and rehabilitation training. He had become seizure-free within half a year of follow-up, but his intelligence and motor development did not improve significantly. Genetic testing revealed that he has harbored a heterozygous c.1720_1722delCTT (p.Lys574del) variant of the HNRNPU gene, which was not found in either of his parents. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was rated as likely pathogenic (PS2+PM2_Supporting+PM4). A total of 13 articles were retrieved, and the types of HNRNPU gene mutations have included splice site mutation, nonsense mutation, missense mutation, in-frame deletion, gene duplication, frameshifting mutation, and multiple exon deletion. The main clinical manifestations have included mental retardation, language delay, global developmental delay, epilepsy, craniofacial deformity, mental and behavioral abnormalities. The c.1720_1722delCTT variant of the HNRNPU gene probably underlay the NDDs in this child. Above finding has enriched the mutational spectrum of the HNRNPU gene.