患儿,女,1~+岁,第1胎足月顺产。父母健康,农民,非近亲婚配,家中无遗传病史。患儿出生时父21岁、母20岁。母孕期无异常。父母否认有饮酒、吸烟、接触农药及放射性物质史。查体:身高72cm,体重5kg,发育营养差,智力显著低下,表情痴呆,不能抬头、坐及站。头小而稍尖,头围38cm,前额狭 Children, women, 1 ~ + years old, the first full-term fetus. Parents health, peasants, non-relatives marriage, family history of no genetic disease. 21 years old when the child was born, female 20 years old. No abnormalities during pregnancy. Parents denied drinking, smoking, exposure to pesticides and radioactive material. Physical examination: height 72cm, weight 5kg, poor nutrition, mental retardation, dementia, can not look up, sit and stand. Head small and slightly pointed, head circumference 38cm, narrow forehead