Clinical Exome Sequencing in Patients with Undifferentiated General Developmental Delay and Intellectual Disabilities

Introduction. Each fifth neurodevelopmental disorder is diagnosed in massively parallel sequencing only. Objective: to present the experience of exome sequencing in children with undifferentiated general developmental delay and intellectual disabilities. Materials and methods. We assessed 33 patients (19 males and 14 females) at the age of 4.5 2.4 years with general developmental delay and intellectual disabilities. We studied patients' medical and family histories and their neurological statuses as well as the findings of neuropsychological testing and clinical exome sequencing. Results.The effectiveness of clinical exome sequencing in the sample was 39.4% (MECP2, WDR45, SYNJ1, ADAR, PMM2, SHANK3, KMT5B, UBE3A, PTPN11, CTNNB1, and MTOR mutations). The pathogenic variants were significantly more prevalent in the patients with motor development delay, 53.8% of patients (P .05). Most incident conditions included insomnias (46.2%), autism spectrum disorders (38.5%), developmental regression (38.5%), and epilepsy (38.5%). Genetic disorders were more common in the female patients . Conclusion. With the study results, we can suppose that ca. 40% of patients with undifferentiated general developmental delay and intellectual disabilities had genetic disorders and, therefore, needed further evaluation with molecular genetic testing.