A cytogenetic abnormality that refers to the allelic loss of all or part of the long arm of chromosome 11. The disease is partial deletion of the long arm of chromosome 11 (MONDO_0016910, a Monarch Disease Ontology entry). Also known as: partial deletion of chromosome 11q, partial deletion of the long arm of chromosome type 11, partial monosomy of chromosome 11q, partial monosomy of the long arm of chromosome 11.