Objective: To explore the genetic basis for two patients from a family with BCL11A-related intellectual disability (BCL11A-ID).
Methods: Clinical data of the proband and her family members was analyzed. Chromosomal karyotyping analysis, trio-whole exome sequencing (trio-WES) and copy number variation sequencing (CNV-seq) were carried out. For the suspected genetic variants, Sanger sequencing was used to verify, and pathogenicity assessment was conducted.
Results: The proband and her mother both had intellectual and language impairment, and their fetal hemoglobin (HbF) was significantly elevated. A heterozygous c.1327_c.1328delTC (p.Ser443Hisfs*128) variant was found in exon 4 of the BCL11A gene by WES, which has resulted in truncated expression of the encoded protein, and Sanger sequencing has verified that the variant was inherited from the mother. The variant was not found in related databases. The variant was predicted as pathogenic according to the guidelines from the American College of Medical Genetics and Genomics (ACMG) (PVS1+PM2+PP1). No karyotypic abnormality was found in the proband, her parents and brother, and no pathogenic CNVs was found in the proband and her parents.
Conclusion: The c.1327_c.1328delTC (p.Ser443Hisfs*128) variant may underlay the BCL11A-ID in the proband and her mother. This de novo variant has expanded the mutational spectrum of the BCL11A gene.