Chung-Lin Lee1, Chen-Hao Lee2, Chih-Kuang Chuang3, Huei-Ching Chiu1, Yen-Jiun Chen1, Chao-Ling Chou1, Peih-Shan Wu4, Chih-Ping Chen5, Hsiang-Yu Lin6, Shuan-Pei Lin7. 1. Department of Pediatrics, Mackay Memorial Hospital, Taipei, Taiwan. 2. Department of Pediatrics, E-DA Hospital, I-Shou University, Kaohsiung City, Taiwan. 3. Medical Research, Mackay Memorial Hospital, Taipei, Taiwan. 4. Gene Biodesign Co. Ltd., Taipei, Taiwan. 5. Medical Research, Mackay Memorial Hospital, Taipei, Taiwan; Departments of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan; Department of Biotechnology, Asia University, Taichung, Taiwan; School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan; Institute of Clinical and Community Health Nursing, National Yang-Ming University, Taipei, Taiwan; Department of Obstetrics and Gynecology, School of Medicine, National Yang-Ming University, Taipei, Taiwan. 6. Department of Pediatrics, Mackay Memorial Hospital, Taipei, Taiwan; Department of Medicine, Mackay Medical College, New Taipei City 25245, Taiwan; Division of Genetics and Metabolism, Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan; Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan; Mackay Junior College of Medicine, Nursing and Management, Taipei, Taiwan. Electronic address: lxc46199@ms37.hinet.net. 7. Department of Pediatrics, Mackay Memorial Hospital, Taipei, Taiwan; Department of Medicine, Mackay Medical College, New Taipei City 25245, Taiwan; Division of Genetics and Metabolism, Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan; Department of Infant and Child Care, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan. Electronic address: 4535lin@gmail.com.
Abstract
BACKGROUND: Unexplained developmental delay or intellectual disability (DD/ID) has an estimated prevalence of about 3%-5% in the general population of Taiwan. Array comparative genomic hybridization (array-CGH) is a high-resolution tool that can detect about 50 Kb chromosome aberrations. A previous study has reported a detection rate of 10%-20% for this array.1 This study aimed to investigate and compare the diagnosis rate for DD/ID using array-CGH and conventional chromosome study in DD/ID patients in Taiwan. METHODS: We enrolled 177 patients with DD/ID who underwent array-CGH examination at the MacKay Memory Hospital between June 2010 and September 2017. The copy number variants (CNV) were classified into the following three groups: pathogenic (potential pathologic variant), benign (normal genomic variant), and uncertain clinical significance (variance of uncertain significance, VOUS), according to the ACMG guideline.2 RESULTS: Of the 177 enrolled patients, 100 (56.5%) were men and 77 (43.5%) were women. Ages ranged from 3 months to 50 years, with a median age of 5.2 years. Total 32.0% (32/100) male patients had pathogenic CNV, and 32.5% (25/77) female patients had pathogenic CNV. The ratio of pathogenic CNV in male and female patients was not significantly different (p = 0.379). The proportions of pathogenic CNV at <3 years, 3-6 years, 6-12 years, 12-18 years, and >18 years of age were 32.3% (31/96), 19.4% (6/31), 34.8% (8/23), 16.7% (2/12), and 66.7% (10/15), respectively. The overall diagnosed rate of DD/ID with pathogenic CNV was 27.7% (49/177) using array-CGH in this study. There were 105 patients with conventional karyotyping and array-CGH data at the same time. Nineteen (18.1%) patients had visible chromosomal abnormality. Total 32/105 (30.5%) patients could find at least one pathogenic CNVs. The array-CGH had a higher diagnosed rate than the conventional karyotyping in clinical application. CONCLUSIONS: Although array-CGH could not detect point mutation, balanced translocations, inversions, or low-level mosaicism, the diagnosis rate in clinical application was up to 46.3% and 2.5 times that of conventional karyotyping analysis (18.1%). This study demonstrated that array-CGH is a powerful diagnostic tool and should be the first genetic test instead of conventional karyotyping analysis for patients with unexplained DD/ID.
BACKGROUND: Unexplained developmental delay or intellectual disability (DD/ID) has an estimated prevalence of about 3%-5% in the general population of Taiwan. Array comparative genomic hybridization (array-CGH) is a high-resolution tool that can detect about 50 Kb chromosome aberrations. A previous study has reported a detection rate of 10%-20% for this array.1 This study aimed to investigate and compare the diagnosis rate for DD/ID using array-CGH and conventional chromosome study in DD/ID patients in Taiwan. METHODS: We enrolled 177 patients with DD/ID who underwent array-CGH examination at the MacKay Memory Hospital between June 2010 and September 2017. The copy number variants (CNV) were classified into the following three groups: pathogenic (potential pathologic variant), benign (normal genomic variant), and uncertain clinical significance (variance of uncertain significance, VOUS), according to the ACMG guideline.2 RESULTS: Of the 177 enrolled patients, 100 (56.5%) were men and 77 (43.5%) were women. Ages ranged from 3 months to 50 years, with a median age of 5.2 years. Total 32.0% (32/100) male patients had pathogenic CNV, and 32.5% (25/77) female patients had pathogenic CNV. The ratio of pathogenic CNV in male and female patients was not significantly different (p = 0.379). The proportions of pathogenic CNV at <3 years, 3-6 years, 6-12 years, 12-18 years, and >18 years of age were 32.3% (31/96), 19.4% (6/31), 34.8% (8/23), 16.7% (2/12), and 66.7% (10/15), respectively. The overall diagnosed rate of DD/ID with pathogenic CNV was 27.7% (49/177) using array-CGH in this study. There were 105 patients with conventional karyotyping and array-CGH data at the same time. Nineteen (18.1%) patients had visible chromosomal abnormality. Total 32/105 (30.5%) patients could find at least one pathogenic CNVs. The array-CGH had a higher diagnosed rate than the conventional karyotyping in clinical application. CONCLUSIONS: Although array-CGH could not detect point mutation, balanced translocations, inversions, or low-level mosaicism, the diagnosis rate in clinical application was up to 46.3% and 2.5 times that of conventional karyotyping analysis (18.1%). This study demonstrated that array-CGH is a powerful diagnostic tool and should be the first genetic test instead of conventional karyotyping analysis for patients with unexplained DD/ID.
Authors: Yi Liu; Yuqiang Lv; Mehdi Zarrei; Rui Dong; Xiaomeng Yang; Edward J Higginbotham; Yue Li; Dongmei Zhao; Fengling Song; Yali Yang; Haiyan Zhang; Ying Wang; Stephen W Scherer; Zhongtao Gai Journal: NPJ Genom Med Date: 2022-01-12 Impact factor: 8.617