<unk>  <unk> , also known as general learning<unk>  in the United Kingdom and formerly mental retardation (MR), is a generalized neurodevelopmental disorder characterized by significantly impaired<unk>  and adaptive functioning. It is defined by an IQ under 70, in addition to deficits in two or more adaptive behaviors that affect everyday, general living.<unk>  functions are defined under DSM-V as reasoning, problem‑solving, planning, abstract thinking, judgment, academic learning, and learning from instruction and experience, and practical understanding confirmed by both clinical assessment and standardized tests. Adaptive behavior is defined in terms of conceptual, social, and practical skills involving tasks performed by people in their everyday lives.<unk>  is subdivided into syndromic<unk> , in which<unk>  deficits associated with other medical and behavioral signs and symptoms are present, and non-syndromic<unk> , in which<unk>  deficits appear without other abnormalities. Down syndrome and fragile X syndrome are examples of syndromic<unk> es.<unk>  affects about 2 to 3% of the general population. Seventy-five to ninety percent of the affected people have mild<unk> . Non-syndromic, or<unk> iopathic cases account for 30 to 50% of these cases. About a quarter of cases are caused by a genetic disorder, and about 5% of cases are inherited from a person's parents. Cases of unknown cause affect about 95 million people .
Intellectual disability
Autism
Developmental disability
Autism spectrum  disorder  1
Global developmental delay
Language delay
Nonverbal autism
Nonverbal learning disorder