21/21易位型先天愚型较少见,多数幼年夭亡,存活至成年的尚属罕见。本文报道一例成年人21/21易位型先天愚型。 患者马××,男性,26岁,未婚。第二胎,7个月早产,出生时体重1.6公斤。两岁会走路,5岁开始学说话。身体及智力发育均明显 21/21 metathesis is less common type of metathesis, most young premature death, survival to adulthood is still rare. This article reports a case of adult 21/21 translocation type Down’s syndrome. Patient × ×, male, 26 years old, unmarried. The second child, 7 months premature, weighs 1.6 kg at birth. Two years old will walk, 5 years old begin to speak. Physical and mental development are obvious