Two Cases of Recessive Intellectual Disability Caused by <i>NDST1</i> and <i>METTL23</i> Variants

• Main Authors: Amjad Khan, Zhichao Miao, Muhammad Umair, Amir Ullah, Mohammad A. Alshabeeb, Muhammad Bilal, Farooq Ahmad, Gudrun A. Rappold, Muhammad Ansar, Raphael Carapito
• Format: Article
• Language: English
• Published: MDPI AG 2020-08-01
• Series: Genes
• Subjects: autosomal recessive intellectual disability; <i>NDST1</i>; <i>METTL23</i>; exome sequencing
• Online Access: https://www.mdpi.com/2073-4425/11/9/1021
• ISSN: 2073-4425

Intellectual disability (ID) is a highly heterogeneous genetic condition with more than a thousand genes described so far. By exome sequencing of two consanguineous families presenting hallmark features of ID, we identified two homozygous variants in two genes previously associated with autosomal recessive ID: <i>NDST1</i> (c.1966G>A; p.Asp656Asn) and <i>METTL23</i> (c.310T>C; p.Phe104Leu). The segregation of the variants was validated by Sanger sequencing in all family members. In silico homology modeling of wild-type and mutated proteins revealed substantial changes in the secondary structure of both proteins, indicating a possible effect on function. The identification and validation of new pathogenic <i>NDST1</i> and <i>METTL23</i> variants in two cases of autosomal recessive ID further highlight the importance of these genes in proper brain function and development.