Fragile-X mental retardation--a combination of cytogenetic and molecular approaches, with greater emphasis on DNA analysis.
Fragile X syndrome is one of the most frequent causes of hereditary mental retardation. In the past, its diagnosis depended primarily on cytogenetic demonstration of chromosome fragile site Xq27.3. Recently, the gene FMR-1 has been found responsible for this disease. Here a combined method was used to study fragile X syndrome. A fragment (pP1fr) of DNA was subcloned from pE5.1 by polymerase chain reaction. With this probe, DNA samples from two cytogenetically proved families were analyzed by restriction fragment length polymorphisms. It was demonstrated that EcoRI polymorphism was an easy and accurate method for diagnosis of the fragile X syndrome. To study methylation status of patients, another methylation-sensitive enzyme, BssHII, could be used together with EcoRI. The PstI polymorphism of one family was also studied and showed one kb fragment as normal, and detected more precise changes in length. Prominent mosaicism necessary was characteristic in PstI polymorphism. The DNA diagnosis of fragile X syndrome was a reliable method.
Department of Pediatrics, University Hospital and College of Medicine, National Taiwan University, Taipei, Taiwan, R.O.C.
T R
TR
Wang
W L
WL
Hwu
J W
JW
Hou
S P
SP
Chou
C H
CH
Liu
D001483:Base Sequence; D002869:Chromosome Aberrations; D004247:DNA / Q000032:analysis*; D005600:Fragile X Syndrome / Q000235:genetics*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction
D004247:DNA