Prenatal diagnosis by whole exome sequencing in a family with a novel TBR1 mutation causing intellectual disability

Abstract

Objective: To provide prenatal diagnosis for a pregnant woman with genetic history of intellectual disability.

Case report: A Chinese pedigree with intellectual disability was collected in this study. Cytogenetic analysis, chromosomal microarray analysis (CMA) and whole exome sequencing (WES) followed by Sanger validation were conducted to identify the genetic pathogenesis. A novel heterozygous deletion c.370_374delTTCCC in TBR1 gene was identified, leading to a frameshift mutation starting at Phe124 followed by a premature stop codon at position 141 (p.Phe124Valfs∗18). Segregation analysis identified that this novel mutation is co-segregated among the affected family members but absent in unaffected family members. Prenatal diagnosis indicated the absence of this mutation, and the family decided to continue the pregnancy after genetic counseling.

Conclusion: Our findings demonstrated the significance of genetic testing in the diagnosis of intellectual disability. This work also confirmed the effectiveness of WES in prenatal diagnosis.

Keywords: Intellectual disability; Prenatal diagnosis; TBR1 mutation; Whole exome sequencing.