患儿,男,9个月,系第3胎足月顺产。出生时体重3,500g。因不会坐,智力迟钝就诊。父母表型、智力正常,身体健康,非近亲婚配。怀孕时年龄分别为33岁和25岁。母无流产史,孕该患儿前曾连服避孕药(药名不详)3个月,孕期中无感染史,未接触化学药物及放射线,无烟、酒嗜好。患儿兄(第1胎)因患小儿麻痹症留有后遗症,但智力正常,其姐表型及智力发育均正 Children, male, 9 months, the third full-term birth of the third child. Birth weight 3,500g. Because they will not sit, mental retardation treatment. Parents phenotype, normal intelligence, good health, non-relatives marriage. At the age of 33 and 25 respectively. Female abortion history, pregnancy before the children had even served the contraceptives (unknown drug name) for 3 months, no history of infection during pregnancy, no exposure to chemical drugs and radiation, smoke-free, alcohol hobby. Children with brother (first child) left polio sequelae, but the intelligence is normal, the sister’s phenotype and mental development are positive