Chromosome Microarray Analysis of 3832 Patients over 15 Years Confirms Genome-Wide Copy Number Variation in Patients with Developmental Disabilities Including Autism.

Ongoing need for chromosome microarray analysis (CMA) characterization prompted the description of all 16,138 copy number variants (CNVs) found in 3832 patients studied from 2009 to 2024, 92% of them with developmental disabilities and/or autism. Detailed reporting shows the overlap of variants qualified as benign (15,083 CNVs, sizes 0.1 Kb-3 Mb) or of uncertain significance (216 CNVs, sizes 11 Kb-20 Mb) with pathogenic CNVs (836, 11 Kb-31 Mb), which are emphasized in most studies. Further distinguishing pathogenic CNVs were 88 recurring microdeletion/duplications and 86 in single patients, with all of the former and 66 of the latter having previous syndrome associations. Diagnoses were provided in 749 (20% of) patients, increasing to 21% among the 2470 patients (2015-2024) with their karyotypes recorded. Diagnoses included 61 known chromosomal syndromes, with CMA confirming or clarifying the abnormal karyotype in 187 (7.6%) or 55 (2.2%). The 90 microdeletions averaged 6439 kb in length (with chromosomes 6, 8, 17, and 22 accounting for most cases), while the 90 microduplications averaged 6895 kb (with chromosomes 8, 14, 17, 22, and X accounting for most cases). Together, these represent an average imbalance of 798,000 nucleotides per patient (0.75% of their genome). Continued reporting that match detailed CNV findings with patient profiles, especially symptom spectra, is needed to optimize CMA potential for presymptomatic diagnosis and therapy.