title: The rare human fragile site 16B.
abstract: The rare human fragile site 16B (FRA16B) has been found to occur spontaneously. Its expression in lymphocyte cultures can also be induced or greatly enhanced by addition of chemicals which are known to bind to AT-rich DNA regions. Following optimal treatment with 150 microg/ml berenil 24 h prior to fixation, the heterozygote frequency of FRA16B is found to be about 5% in populations of European descent. Thus, FRA16B represents the most common of the rare fragile sites. Consistent with cytogenetic observations, the molecular characterization of FRA16B revealed that it is an amplified 33-base pair AT-rich minisatellite repeat. These interindividually variable, extremely large repeat expansions of 15-70 kb in size do not seem to interfere with the expression of genes essential for human development since heterozygotes and homozygotes for FRA16B are normal.
authors.affiliation: Institut für Humangenetik, Biozentrum, Würzburg, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Felbor
authors.forename: W
authors.initials: W
authors.lastname: Feichtinger
authors.forename: M
authors.initials: M
authors.lastname: Schmid
mesh_terms: D002869:Chromosome Aberrations / Q000139:chemically induced; D002871:Chromosome Banding; D043283:Chromosome Fragile Sites / Q000235:genetics*; D002885:Chromosomes, Human, Pair 16 / Q000235:genetics*; D004133:Diminazene / Q000031:analogs & derivatives* / Q000494:pharmacology; D004214:Distamycins / Q000494:pharmacology; D006801:Humans; D007621:Karyotyping
chemical_list: D004214:Distamycins; C030000:stallimycin; C003915:diminazene aceturate; D004133:Diminazene