Fragile X mental retardation 1 is the gene underlying fragile X syndrome (FXS). Its product, fragile X mental retardation protein, is closely involved with development of brain and neurons. PCR and Southern blotting have been the major methods for laboratory diagnosis of FXS. In this article, the progress in the molecular diagnosis of FXS is reviewed.
Fragile X Mental Retardation Protein ; genetics ; Fragile X Syndrome ; diagnosis ; genetics ; Humans ; Pathology, Molecular ; methods

OBJECTIVE: To determine the CGG repeat number and methylation status of FMR1 gene for fetuses whose mothers have carried a FMR1 mutation. METHODS: For 30 pregnant women, the fetal CGG repeat number was determined with a GC-rich PCR system by using chorionic villus, amniotic fluid or umbilical blood samples. The methylation status of the FMR1 gene was confirmed with Southern blotting. RESULTS: In total 30 prenatal diagnoses were performed for 29 carriers of FMR1 gene mutations and 1 with FMR1 gene deletion mosaicism. Three fetuses were found to carry premutations, 9 were with full mutations and 1 with mosaicism of premutation and full mutations. Eighteen fetuses were normal. CONCLUSION Considering the genetic complexity of Fragile X syndrome (FXS), single method may not suffice accurate determination of their genetic status. The pitfalls and technical limitations of protocols requires adoption of personalized strategy for its prenatal diagnosis.
Female ; Fragile X Mental Retardation Protein ; genetics ; Fragile X Syndrome ; diagnosis ; Heterozygote ; Humans ; Mutation ; Pregnancy ; Prenatal Diagnosis

OBJECTIVETo establish a method of methylation-sensitive restriction enzymes based quantitative PCR (MSRE-qPCR) for analysis of CpG island DNA of FMR1 gene, and to assess its value for molecular diagnosis of fragile X syndrome.

METHODSThirty boys with mental retardation and abnormal repeats of 5'(CGG)n in the FMR1 gene and 20 mothers were analyzed by conventional PCR screening. Eag I was used to digest genomic DNA, and qPCR was performed to amplify CpG island in the FMR1 gene using both undigested and digested templates. Raw Ct values were obtained through quantitative PCR amplification. The degree of CpG island methylation was calculated by 2 - U+0394 U+0394 Ct. The result of MSRE-qPCR was verified by Southern blotting. 30 healthy females and 30 healthy males were used as controls to optimize the established MSRE-qPCR method.

RESULTSThe ranges of 2 - U+0394 U+0394 Ct value for normal methylation, partial methylation and full methylation were determined. Among the 30 patients, 3 were found to have partial methylation of CpG island of the FMR1 gene, and 27 were found to have full methylation (3/30 results were verified by Southern blotting). Only 7 mothers were found abnormal methylation of CpG island of FMR1 gene, whilst the remaining 13 mothers were normal.

CONCLUSIONMSRE-qPCR is a quick and reliable method for quantitative analysis of CpG island methylation status in FMR1 gene, which may provide a new strategy for the diagnosis of fragile X syndrome.

CpG Islands ; DNA Methylation ; Female ; Fragile X Mental Retardation Protein ; genetics ; Fragile X Syndrome ; diagnosis ; genetics ; Humans ; Male ; Sex Factors

Fragile X-associated tremor/ataxia syndrome(FXTAS) is a neurodegenerative disease caused by FMR1 gene permutation(PM). The main clinical manifestations are intention tremor and/or ataxia, and the pathogenesis was related to RNA toxicity. In this paper, the research progress of clinical manifestatios, pathological characteristics, epidemiology and molecular mechanisms will be reviewed.
Ataxia ; genetics ; Female ; Fragile X Mental Retardation Protein ; genetics ; Fragile X Syndrome ; complications ; diagnosis ; genetics ; pathology ; Humans ; Male ; Tremor ; genetics

OBJECTIVE: To analyze the (CGG)n repeats of FMR1 gene among patients with unexplained mental retardation. METHODS: For 201 patients with unexplained mental retardation, the (CGG)n repeats of the FMR1 gene were analyzed by PCR and FragilEase RESULTS: For the 201 patients with unexplained mental retardation, 15 were identified with full mutations of the FMR1 gene. The prevalence of fragile X syndrome (FXS) in patients with unexplained mental retardation was determined as 7.5% (15/201). Prenatal diagnosis was provided for 6 pregnant women with pre- or full mutations. Analysis revealed that women with mental retardation and full FMR1 mutations exhibited a skewed XCI pattern with primary expression of the X chromosome carrying the mutant allele. CONCLUSION FXS has a high incidence among patients with unexplained mental retardation. Analysis of FMR1 gene (CGG)n repeats in patients with unexplained mental retardation can facilitate genetic counseling and prenatal diagnosis for their families. FMR1 gene (CGG)n repeats screening should be recommended for patients with unexplained mental retardation.
Female ; Fragile X Mental Retardation Protein/genetics* ; Fragile X Syndrome/genetics* ; Humans ; Intellectual Disability/genetics* ; Mutation ; Pregnancy ; Prenatal Diagnosis

The fragile X syndrome is a common X-linked mental retardation and autism, affecting females as well as males. The fragile site X chromosomes were studied in a series of 153 mentally retarded boys of unknown etiology to determine the frequency of fragile X syndrome, and to assess the feasibility of making a clinical diagnosis of the fragile X syndrome in young boys before cytogenetic results were known. The 10 boys (6.4%) were positive for fra (X) (q27). The phenotype of fra (X) (q27) positive patients were typical except one who also had sex chromosomal mosaicism. There were three pairs of siblings among the fra (X) (q27) positive patients. Frequency of expression of the fragile site was in 10 to 47 per cent of cells. In addition, 19 boys showed a previously unsuspected chromosomal abnormality. The frequency of the fragile X syndrome in the present study is not significantly different from those in Caucasians and Japanese population. The fragile X syndrome can be recognized by noting key aspects of family history as well as the clinical features in mentally retarded boys.
Child ; Child, Preschool ; Fragile X Syndrome/diagnosis/epidemiology/*genetics ; Humans ; Intellectual Disability/*genetics ; Karyotyping ; Male

OBJECTIVEFragile X syndrome (FXS) may be identified by many methods, such as PCR assay and Southern blot. However, each method has its limits or shortcomings. This study explored the reliability of the rapid, convenient and inexpensive hair root fragile X mental retardation protein (FMRP ) assay in the identification of FXS.

METHODSFMRP in hair roots was determined by immunohistochemistry assay in 80 healthy children, in 40 children with mental retardation of unknown etiology and in 12 family members in one pedigree of FXS. FXS was confirmed by 7-deza-dGTP PCR.

RESULTSThere was a high expression of FMRP in hair roots (> or =80%) in healthy children. Two children were confirmed with FXS by 7-deza-dGTP PCR in 40 children with mental retardation of unknown etiology. FMRP expression was 10% and zero respectively in the two children. The other 38 children had FMRP expression of more than 80%. FMRP was not expressed in the two cases of FXS from the pedigree of FXS.

CONCLUSIONSInexpensive, rapid and convenient hair root FMRP assay is reliable for the diagnosis of FXS and may be widely applied for screening and diagnosing FXS in children with mental retardation.

Adolescent ; Child ; Child, Preschool ; Female ; Fragile X Mental Retardation Protein ; analysis ; Fragile X Syndrome ; diagnosis ; genetics ; Hair ; chemistry ; Humans ; Infant ; Male ; Polymerase Chain Reaction

The purposes of this study were to present DNA analysis findings of our case series of fragile X syndrome (FXS) based on methylation-specific polymerase chain reaction (MS-PCR), PCR, and Southern blotting alongside developmental characteristics including psychological profiles and to review the literature on FXS in Korea. The reports of 65 children (male:female, 52:13; age, 6.12+/-4.00 yrs) referred for the diagnosis of FXS over a 26-months period were retrospectively reviewed for the identification of full mutation or premutation of fragile X mental retardation 1 (FMR1). Among the 65 children, there were 4 boys with full mutation, and one boy showed premutation of FMR1, yielding a 6.15% positive rate of FXS. All 4 children with full mutation showed significant developmental delay, cognitive dysfunction, and varying degrees of autistic behaviors. The boys with premutation showed also moderate mental retardation, severe drooling, and behavioral problems as severe as the boys with full mutation. Thirteen articles on FXS in Korea have been published since 1993, and they were reviewed. The positive rate of FXS was in the range of 0.77-8.51%, depending on the study groups and the method of diagnosis. Finally, the population-based prevalence study on FXS in Korea is required in the near future.
Child ; Child, Preschool ; Female ; Fragile X Mental Retardation Protein/*genetics ; Fragile X Syndrome/diagnosis/*epidemiology/*genetics ; Humans ; Infant ; Korea/epidemiology ; Male ; Mutation ; Prevalence

Central Nervous System Diseases ; diagnosis ; genetics ; Fragile X Syndrome ; genetics ; Genotype ; Humans ; Molecular Biology ; Phenotype ; Spinocerebellar Ataxias ; diagnosis ; genetics ; Syndrome

Fragile X syndrome is the most common cause of inherited mental retardation. It accounts for 0.2% - 2.7% of patients with mental retardation, based upon the molecular genetic diagnosis. However, the exact prevalence of fragile X syndrome in Korean patients with mental retardation is unknown. We have performed cytogenetic and molecular analysis for fragile X syndrome in 212 Korean patients with mental retardation. Among them, six patients (2.8%) was identified as carrying fragile X syndrome by both cytogenetic and molecular analysis. The results by cytogenetic analysis was identical to those by molecular analysis. Cytogenetic analysis of 6 carriers (mothers of patients with proven fragile X syndrome) showed a fragile X chromosome in one patients (16.7%) while molecular analysis revealed premutation in all patients. PCR method using Klentaq1 Pfu polymerase showed the same results as those by PCR method using Exo(-) Pfu polymerase, but the former method is recommended because of its simplicity in technical aspect. These data suggest that the prevalence of fragile X syndrome in Korean patients with mental retardation is 2.8%, not significantly different from those in Caucasians.
Cytogenetic Analysis ; Cytogenetics ; Diagnosis ; Fragile X Syndrome* ; Humans ; Incidence* ; Intellectual Disability* ; Molecular Biology ; Polymerase Chain Reaction ; Prevalence ; X Chromosome