Monarch Disease Ontology term MONDO_0019908 (ring chromosome 15) is a chromosome abnormality that affects growth, learning, and speech. People with ring chromosome 15 often have growth delays before and after birth, resulting in short stature; varying degrees of intellectual disability ; low muscle tone (hypotonia); craniofacial malformations; and limb abnormalities. Other symptoms might include congenital heart defects, kidney problems, congenital dislocation of the hips, and cafe-au-lait spots. Ring chromosome 15 is caused by an abnormal chromosome known as a ring chromosome 15 or r(15). A ring chromosome is a circular structure that occurs when a chromosome breaks in two places and the broken ends fuse together. The features of ring chromosome 15 appear to result from the loss (deletion) of genetic material from the long (q) arm of chromosome 15. Ring chromosome 15 is usually caused by spontaneous (de novo) errors very early in embryonic development. In rare cases, it is passed through families, either from a parent who also has a ring chromosome 15, or from a parent who has a balanced translocation. Treatment for ring chromosome 15 is focused on addressing the symptoms present in each individual and may require a team of medical specialists. Also known as: Chromosome 15 Ring, Ring chromosome type 15.