A form of intellectual disability, a disorder characterized by significantly below average general intellectual functioning associated with impairments in adaptive behavior and manifested during the developmental period. Intellectual deficiency is the only primary symptom of non-syndromic intellectual disability, while syndromic intellectual disability presents with associated physical, neurological and/or psychiatric manifestations. MRT71 features include impaired intellectual development, global developmental delay, mildly delayed walking, poor language, seizures in the first years of life, and behavioral abnormalities. The disease is EFO_0010280 (intellectual developmental disorder, autosomal recessive 71).