RT Journal Article SR Electronic T1 Replication status of fragile X(q27.3) in 13 female heterozygotes. JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 407 OP 410 DO 10.1136/jmg.23.5.407 VO 23 IS 5 A1 Tuckerman, E A1 Webb, T A1 Thake, A YR 1986 UL http://jmg.bmj.com/content/23/5/407.abstract AB Chromosome analysis, after bromodeoxyuridine incorporation and a sequential Leishman acridine orange staining method previously described, was used to assess the percentage of early or active fragile Xs compared with the overall total in informative cells in 13 heterozygous females. The percentage thus obtained was then used to calculate the percentage of early or active fragile X that would be expected in a culture without bromodeoxyuridine, that is: percentage active fragile X divided by 100 X percentage fra(X) in standard 199 or M culture. Five females were normal and eight of below normal intelligence. In one culture pokeweed mitogen was substituted for phytohaemagglutinin and the percentage of active fragile Xs obtained was compared with that obtained with phytohaemagglutinin. In the same female the effect of addition of fluorodeoxyuridine and methotrexate on the replication ratio of the X was also investigated. R banded and G banded cells from this subject were also scanned for the deletion of Xq27.3----qter.