Our analysis of sulcal geometry in a selected group of high-functioning participants with WS relative to a healthy, IQ-matched control group revealed significant depth reductions bilaterally in the PS, with additional significant reductions observed in the left orbitofrontal region and in the left collateral sulcus Although gyral and sulcal patterns are highly heritable, andemerge in a tightly controlled sequence during development,very little is known about specific genetic contributions toabnormal gyrification or the resulting functional consequences.Williams syndrome (WS), a genetic disorder caused by hemizygousmicrodeletion on chromosome 7q11.23 and characterized by abnormalbrain structure and striking cognitive (impairment in visuospatialconstruction) and behavioral (hypersocial/anxious) phenotypes,offers a unique opportunity to study these issues.