"Spontaneous" FRA16B is a hot spot for sister chromatid exchanges.
Six heterozygous carriers of a fragile site at 16q22 were available for the current study. We demonstrated that the observed fragile site was a "BrdUrd-sensitive" fra(16)(q22) or FRA16B, capable of spontaneous expression in some individuals (= "spontaneous" FRA16B). Significant differences either in spontaneous or in ethylmethane sulfonate (EMS)-induced sister chromatid exchange (SCE) frequencies were found between the fragile 16q22 site, whether expressed or not, and its homologous normal site. These data complement our previous findings on FRAXA and provide additional arguments indicating that fragility and SCE are variable cytogenetic expressions of the same DNA structural alteration.
Center for Human Genetics, University of Leuven, Belgium.
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T
Lukusa
E
E
Meulepas
J P
JP
Fryns
H
H
Van den Berghe
J J
JJ
Cassiman
D002871:Chromosome Banding; D043283:Chromosome Fragile Sites; D002873:Chromosome Fragility; D002885:Chromosomes, Human, Pair 16; D005787:Gene Frequency; D006801:Humans; D012854:Sister Chromatid Exchange