In the article, we used PCR - gel elec-trophoresis method to determine the number of repeat of P(CGG) n. We have 126 normal X chromosomes and 18 X chromosomes obtained from fra (X)families.

• 采用PCR凝胶电泳法测定126条正常人群X染色体及来源于脆性X综合征家族的18条染色体的P(CGG)n重复数目。