A chromosomal deletion syndrome that is characterized by mild-to-moderate infantile hypotonia, minor skeletal anomalies, prepubertal short stature, brachydactyly, ophthalmologic and otolaryngologic abnormalities, peripheral neuropathy, developmental delay, cognitive impairment, and behavioral abnormalities that has_material_basis_in a 3.7-Mb interstitial deletion in chromosome 17p11.2 or sometimes by mutations in the RAI1 gene in the same region.