先天愚型先天愚型是儿科方面不很少见的一种先天性疾病。患者智能低,鼻小,面阔而稍平,口半张,舌常伸出口外,手宽,掌纹呈通贯手,常伴有先天性心脏病等其他先天性畸形。患者的体细胞染色体数是2n=47,比正常人多1个近端着丝粒染色体,这 Down’s syndrome Down’s syndrome is a rare congenital disorder in pediatrics. Patients with low intelligence, nose small, Miankuo and slightly flat, half a mouth, tongue often extended outside the mouth, hand wide, palmprint was hand through, often accompanied by congenital heart disease and other congenital malformations. The patient’s somatic chromosome number is 2n = 47, one more centromeric chromosome than normal, which