先天愚型即 Down综合征是一种最常见的染色体病 ,是遗传性智力低下的最常见原因 ,新生儿发病率约占 1/ 6 0 0～ 1/80 0。我室自 1983年 / 1999年共检出 15 0例先天愚型患者 ,经细胞遗传学分析及临床研究 ,现总结如下。1　对象和方法1.1　对象　被检 15 0例先天性愚型患者男 85 Down syndrome is the most common type of Down’s syndrome, the most common cause of hereditary mental retardation. The incidence of neonates is about 1/60 to 1/80. A total of 150 patients with Down’s syndrome were detected in our hospital from 1983 to 1999. The cytogenetic analysis and clinical studies are summarized as follows. 1 objects and methods 1.1 object was seized 150 cases of idiotypic patients in men and 85