FRAXE mutation in mentally retarded patients using the OxE18 probe.
The folate-sensitive fragile site FRAXE is located in proximal Xq28 of the human X chromosome and lies approximately 600 kb distal to the fragile X syndrome (FRAXA) fragile site at Xq27.3. Although FRAXA and FRAXE are indistinguishable by means of conventional cytogenetics, they can now be delineated at the molecular level and provides the basis for a proper diagnosis. The screening for CGG amplifications in the FMR1 gene was based on standard protocols using EcoRI digests on Southern blots and hybridization with the StB12.3 probe. The FRAXE mutation was analyzed by digestion with HindIII and the filters were probed with OxE20. We present the results of 144 patients referred for fragile X testing but negative for the FMR1 gene trinucleotide expansion, that were also screened for the FMR2 expansion. For FRAXE mutation a molecular protocol for OxE18 probe was used, in the DNA samples digested with EcoRI on the same blots as those used for detection of FRAXA. None of the patients tested were positive for the FRAXE expansion. This technique was successfully established into our laboratory routine showing the practical use of testing for FRAXA and FRAXE in a large series of patients.
Mulatinho
M V
MV
Department of Cell Biology and Genetics, Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, Brazil.
Llerena
J C
JC
Pimentel
M M
MM
D015139:Blotting, Southern; D001938:Brazil; D015342:DNA Probes / Q000235:genetics*; D015246:Deoxyribonuclease EcoRI; D015247:Deoxyribonuclease HindIII; D005260:Female; D051860:Fragile X Messenger Ribonucleoprotein 1; D005600:Fragile X Syndrome / Q000175:diagnosis / Q000235:genetics*; D005820:Genetic Testing; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D008297:Male; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics; D009687:Nuclear Proteins; D011506:Proteins / Q000235:genetics; D016601:RNA-Binding Proteins; D015534:Trans-Activators; D018911:Trinucleotide Repeats
D015342:DNA Probes; D015246:Deoxyribonuclease EcoRI; D015247:Deoxyribonuclease HindIII; D051860:Fragile X Messenger Ribonucleoprotein 1; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D011506:Proteins; D016601:RNA-Binding Proteins; D015534:Trans-Activators; C099930:AFF2 protein, human; C497683:FMR1 protein, human