Clinical exome sequencing reveals an important role for clinical diagnosis of intellectual disability with definition of seven novel variants

Intellectual disability can be defined as a significantly below-average general mental function, accompanied by environmental adaptation and behavioural deterioration. Patient files of 87 children with intellectual disability were evaluated in this study. After clinical exclusion criterias, clinical exome sequencing was performed for 25 of 87 intellectual disability cases with a massively parallel targeted sequencing method. Seventeen variants in the genes MBOAT7, KDM5C, TUBB3, MAN1B1, GFAP, CACNA1A, BCOR, LMNA, LBR, ALS2, ENPP1, UBE3A, TRAPPC9, HSPG2, AFF2, NLGN4, and SOX10 were identified in 14 of 25 patients (56%). Seven of the 17 variants (41.1%) were novel in the genes KDM5C, BCOR, UBE3A, TRAPPC9, AFF2, NLGN4, and SOX10. Seven cases (7/25, 28%) had a definite diagnosis of intellectual disability with their pathogenic variants. The high rate of variant detection (56%) in the current study shows that multiple gene analysis plays an essential role in diagnosing the uncertain etiology of intellectual disability. This study also presents seven novel variants, which are first reported.