Ring chromosome 17 syndrome is a rare chromosomal anomaly syndrome, resulting from partial deletion of chromosome 17, characterized by highly variable manifestations, ranging from a severe phenotype which presents with lissencephaly and severe intellectual disability to a milder phenotype that includes short stature, microcephaly, intellectual disability, seizures (that may be pharmacoresistant), café-au-lait spots, retinal flecks and minor facial dysmorphism, depending on the presence or absence of the Miller-Dieker critical region. The disease is ring chromosome 17 (Monarch Disease Ontology term MONDO_0015433). Also known as: Ring chromosome type 17.