[Identification of a novel nonsense IQSEC2 variant in a child with X-linked intellectual disability]

Area of Science:

• Genetics
• Neurodevelopmental Disorders

Background:

• Intellectual disability (ID) is a complex neurodevelopmental disorder with diverse genetic etiologies.
• X-linked intellectual disability (XLID) accounts for a significant proportion of ID cases, highlighting the importance of genes on the X chromosome.

Purpose of the Study:

• To investigate the genetic underpinnings of a child presenting with X-linked intellectual disability.
• To identify novel genetic variants associated with intellectual disability and related phenotypes.

Main Methods:

• Whole exome sequencing was performed on DNA from the affected child and his parents.
• Potential pathogenic variants were identified and subsequently validated using Sanger sequencing.
• Bioinformatic tools were employed to predict the functional impact of identified variants.

Main Results:

• A previously unreported de novo nonsense variant, c.3163C>T (p.Arg1055*), in the IQSEC2 gene was identified in the child.
• Bioinformatic predictions indicated that this variant is pathogenic, likely disrupting the IQSEC2 protein's PH domain and leading to loss of function.
• The variant is predicted to cause significant structural damage to the IQSEC2 protein.

Conclusions:

• The identified de novo nonsense variant in the IQSEC2 gene is strongly implicated as the cause of the child's intellectual disability and associated symptoms.
• This finding expands the known genetic spectrum of intellectual disability and underscores the role of IQSEC2 in neurodevelopment.