Carpenter syndrome (Monarch Disease Ontology term MONDO_0019012) is an extremely rare autosomal recessive syndrome characterized by premature closure of cranial sutures leading to cone-shaped head, fusion of the digits, and the presence of more digits than normal. It may be associated with heart defects, single horseshoe-shaped kidney, short stature, undescended testes, and mild mental retardation. Also known as: ACPS2, Carpenter 's syndrome, acrocephalopolysyndactyly type 2, acrocephalopolysyndactyly type II, type II Acrocephalopolysyndactyly.