过去曾报导过若干人类染色体具有遗传性脆性位点,其中大多数位点要在缺乏叶酸的培养基中才能得到最大的表达。也有人曾报导过仅在培养基内加入BrdU诱发脆性位点fra(10)(q25)的出现。本文最近发现一个家庭有fra(10)(q25)的自发表达。先证者为1例16岁的女患者,她患有明显的进行性运动失调,伴有视力障碍,轻度精 It has been reported in the past that a number of human chromosomes have hereditary brittle loci, most of which are to be expressed maximally in media lacking folic acid. It has also been reported that the addition of BrdU to medium only induces the appearance of the fragemic site fra (10) (q25). This article recently found that a family has a spontaneous expression of fra (10) (q25). A proband was a 16-year-old female patient with significant progressive dyskinesia, with visual impairment, mild