Koolen-De Vries syndrome

Chromosome 17q21.31 deletion syndrome, also known as Koolen-de Vries syndrome, is a clinically recognizable multisystem disorder characterized by mild- to-moderate intellectual disability, hypotonia, and characteristic dysmorphic facial features. Other clinically important features include epilepsy, heart defects, and urogenital anomalies. The syndrome was initially described in association with microdeletions at the 17q21.31 locus; however, heterozygous mutations in KANSL1, a gene within the common deletion region, can produce the phenotype as well.