Intellectual disability Severe intellectual disability 2010-08-03T06:29:35Z Severe intellectual disability (ID) is defined as a type of ID characterized by severely sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) the range of 20-34. HP:0010864 Early and severe mental retardation Persons with severe mental retardation can be taught basic life skills and simple tasks with supervision. HP:0007196 Mental retardation, severe Intellectual disability, severe SNOMEDCT_US:40700009 UMLS:C0036857 Severe mental retardation