Williams syndrome (WS) is a neurodevelopmental disorder that results from a heterozygous microdeletion on chromosome 7q11.23. Most of the time, the affected region contains ~1.5 Mb of sequence encoding approximately 24 genes. Some 5–8% of patients with WS have a deletion exceeding 1.8 Mb, thereby affecting two additional genes, including GTF2IRD2. Currently, there is no consensus regarding the implications of GTF2IRD2 loss for the neuropsychological phenotype of WS patients. Objectives: The present study aimed to identify the role of GTF2IRD2 in the cognitive, behavioral, and adaptive profile of WS patients. Methods: Twelve patients diagnosed with WS participated, four with GTF2IRD2 deletion (atypical WS group), and eight without this deletion (typical WS group). The age range of both groups was 7–18 years old. Each patient’s 7q11.23 deletion scope was determined by chromosomal microarray analysis. Cognitive, behavioral, and adaptive abilities were assessed with a battery of neuropsychological tests. Results: Compared with the typical WS group, the atypical WS patients with GTF2IRD2 deletion had more impaired visuospatial abilities and more significant behavioral problems, mainly related to the construct of social cognition. Conclusions: These findings provide new evidence regarding the influence of the GTF2IRD2 gene on the severity of behavioral symptoms of WS related to social cognition and certain visuospatial abilities. (JINS, 2018, 24, 896–904)

High-resolution genomic tests have the potential to revolutionize healthcare by vastly improving mutation detection. The use of chromosomal microarray (CMA) represents one of the earliest examples of these new genomic tests being introduced and disseminated in the clinic. While CMA has clear advantages over traditional karyotyping in terms of mutation detection, little research has investigated the process by which CMA was implemented in clinical settings. Fifteen key informants, six clinicians, and nine laboratory scientists from four Australian states were interviewed about their experiences during and in the time since CMA was adopted for clinical use. Participants discussed challenges such as result interpretation and communication. Strengths were also highlighted, including the collaborative approaches of some centers. Clinical experiences and opinions can inform larger studies with a range of stakeholders, including patients. The historical perspectives from this retrospective study can be helpful in guiding the implementation of future genomic technologies such as whole exome/genome sequencing.