[P2-189] Clinical and genetic analysis on 108 idiopathic intellectual disability / global development delay patients
[Objective] To diagnose etiologically about 108 idiopathic intellectual disability / global development delay(ID/GDD) by clinical and genetic analysis．[Methods] Clinical data from 108 enrolled subjects were collected, and etiologic tests including screening for inborn errors of metabolism, G-banded karyotype, multiplex ligation-dependent probe amplification(MLPA) to detect subtelomeric rearrangement, target next-generation sequencing (NGS) gene panels related to ID and comprehensive chromosomal microarray analysis(CMA) were performed in turn. [Results] All 108 subjects obtained idiopathic ID/GDD diagnosis. Congenital malformation, epilepsy, and autism-like symptoms were manifested in 55.6% (60/108 cases), 22.2% (24/108 cases) and 19.4% (21/108 cases) patients, respectively. 13.9% (15/108) patients harbored positive family history. And abnormal founding were discovered in 60% (54/90) patients’ MRI images. Genetic etiologies were established in 35.2% (38/108 cases) patients through genetic analysis, which consisted of 10(26.3%, 10/38) abnormal chromosome rearrangement, 15(39.5%, 15/38) Mendelian disorders and 16(42.1%, 16/38) microdeletion and microduplication syndromes (MMS). Diagnosis rate of screening for inborn errors of metabolism, karyotype, MLPA, target NGS, CMA, (karyotype + target NGS +CMA) were 0% (0/86 cases), 8.1% (7/86 cases), 6.0% (4/67 cases), 17.9% (15/84 cases), 33.3% (16/48 cases), and 45.7% (21/46 cases), respectively. [Conclusion] Etiology diagnosis for 38 patients with ID/GDD were confirmed, which makes definite genetic counselling and prenatal diagnosis possible. MMS accounted for almost half of our ID/DD patients with known etiologies, and Mendelian disorders was a little lower than it. Among karyotype, MLPA, target NGS, CMA, CMA was the single most efficient diagnostic test, which was consistent with previous reports. And combing karyotype, target NGS, and CMA could increase the rate of etiologic diagnosis to 45.7%.