Mondo Description Monosomy 17q21.31 (17q21.31 microdeletion syndrome) is a chromosomal anomaly characterized by developmental delay, childhood hypotonia, facial dysmorphism, and a friendly/amiable behavior.

Disease Ontology Description A syndrome that is characterized by developmental delay, intellectual disability, muscle weakness (hypotonia), epilepsy, distinctive facial features and congenital malformations of the heart, urogenital tract and the central nervous system, and has_material_basis_in either a chromosome 17 (17q21.31) microdeletion or a mutation in the KANSL1-gene.