A genotype-first approach for the molecular and clinical characterization of uncommon de novo microdeletion of 20q13.33. Homo sapiens

Molecular cytogenetic techniques such as microarray analysis have allowed for a “genotype-first” approach to the characterization of chromosome abnormalities: in the absence of clinical features suggestive of a specific syndrome, patients with similar copy number imbalances can be examined for common clinical features. Using a genotype-first approach, we characterized microdeletions at 20q13.33 in six patients referred for genetic evaluation of developmental delay, mental retardation, and/or congenital anomalies. These deletions are relatively rare, with only 11 cases reported. A comparison to previously reported cases of 20q13.33 microdeletion shows phenotypic overlap, with clinical features that include mental retardation, developmental delay, speech and language deficits, seizures, and behavior problems such as autistic spectrum disorder. Based on analysis of the smallest region of overlap (SRO) among cases reported here and in previous studies, we discuss several possible candidate genes for specific clinical features, including ARFGAP1, CHRNA4, KCNQ2, and MYT1. Deletion of this region may play an important role in cognitive development. Overall design: aCGH control vs. patient, total of 6 patients