[Genetic diagnosis and prenatal genetic diagnosis of fragile X syndrome].
In order to obtain a simple,fast,accurate and low-cost diagnosis method of fragile X syndrome, cytogenetic tests and molecular genetic tests were carried out with direct amplification of (CGG)(n) repeat sequence in 5' terminal of FMR1 gene by PCR and the cDNA sequence of FMR1 by RT-PCR from six mental retardation pedigrees. The proband of pedigree A with high expression of fragile X chromosome(35/273) was detected to be a full mutation patient of fragile X syndrome by the molecular genetic test. There is no expression of fragile X chromosome in the proband and his mother of pedigree B, which was further confirmed as a non-fragile X pedigree by the molecular genetic test. A male foetus of the pedigree C has fragile X chromosome(5/93), but the proband and his mother has no fragile X chromosome. By further detection using molecular genetic test, the male foetus is a full mutation patient of fragile X syndrome, his mother is a permutated carrier, and his brother is a mosaic patient. The proband of pedigree D has high expression of fragile X chromosome (17%), his sister also has expression of fragile X chromosome (5%). By further detection with molecular genetic test, the proband is a full mutation patient of fragile X syndrome,and his sister is a mosaic patient. The probands of pedigrees E and F of the mother were found with suspicions fragile X chromosome, being confirmed as the non-fragile X pedigrees by the molecular genetic test. The conclusion is that the analysis test with direct amplification of 5'j(CGG)n repeat sequence and cDNA sequence in FMR1 gene is simple,fast,low-cost and can be applied in screening, diagnosis and prenatal diagnosis of fragile X syndrome.
Wu
Ling-Qian
LQ
National Laboratory of medical Genetics,Centralsouth University,Changsha 410078, China. wulingqian@163.net
Pan
Qian
Q
Long
Zhi-Gao
ZG
Zhu
Jun-Zhen
JZ
Dai
He-Ping
HP
Zheng
Duo
D
Xia
Kun
K
Huang
Xing-Qing
XQ
Xia
Jia-Hui
JH