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

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 study the pattern of CGG repeat instability within germline cells derived from two male fetuses affected with Fragile X syndrome (FXS).

METHODSThe length and methylation status of CGG repeats within the testes of a fetus carrying a full FXS mutation and another fetus carrying mosaicism FXS mutation were analyzed with Southern blotting and AmplideX FMR1 PCR. Immunohistochemistry was also applied for the measurement of FMR1 protein (FMRP) expression within the testes.

RESULTSFor the fetus carrying the full mutation, Southern blotting analysis of the PCR product has detected an expected band representing the full mutation in its brain and a premutation band of > 160 CGG repeats in its testis. Whereas the pattern of premutation/full mutation in mosaic testis was similar to that in peripheral blood and no sign of contracted fragment was found other than a band of about 160 CGG repeats. Immunohistochemistry assay with a FMRP-specific antibody demonstrated a number of FMRP-positive germ cells, which suggested a contraction from full mutation to premutation alleles.

CONCLUSIONThis study has clarified the instability pattern of CGG repeat and expression of FMRP protein within the testes of fetuses affected with FXS, confirming that the CGG repeat can contract progressively within the germline. The FMRP expression in the testis is consistent with spermatogonium proliferation, and thus the contraction from full mutation to unmethylated premutations may occur for the requirement of FMRP expression during spermatogenesis. The better understanding of FMRP function during germ cell proliferation may elucidate the mechanism underlying the contraction of full FXS mutation in male germline.

Abortion, Eugenic ; Blotting, Southern ; Brain ; embryology ; metabolism ; DNA Methylation ; Fatal Outcome ; Fetus ; cytology ; metabolism ; Fragile X Mental Retardation Protein ; genetics ; metabolism ; Fragile X Syndrome ; diagnosis ; genetics ; Humans ; Immunohistochemistry ; Male ; Mosaicism ; Mutation ; Polymerase Chain Reaction ; Spermatozoa ; metabolism ; Testis ; cytology ; embryology ; metabolism ; Trinucleotide Repeat Expansion ; genetics

ObjectiveTo investigate the clinical (including reproductive) manifestations and genetic characteristics of familial fragile X syndrome (FXS).

METHODSWe collected the clinical data about a case of familial FXS by inquiry, testicular ultrasonography, semen analysis, determination of sex hormone levels, and examinations of the peripheral blood karyotype and Y chromosome microdeletions. Using Southern blot hybridization, we measured the size of the CGG triple repeat sequence of the fragile X mental retardation-1 (FMR1) gene and determined its mutation type of the pedigree members with a genetic map of the FXS pedigree.

RESULTSAmong the 34 members of 4 generations in the pedigree, 3 males and 1 female (11.76%) carried full mutation and 9 females (26.47%) premutation of the FMR1 gene. Two of the males with full FMR1 mutation, including the proband showed a larger testis volume (>30 ml) and a higher sperm concentration (>250 ×10⁶/ml), with a mean sperm motility of 50.5%, a mean morphologically normal sperm rate of 17.5%, an average sperm nuclear DNA fragmentation index (DFI) of 18.5%, a low level of testosterone, normal karyotype in the peripheral blood, and integrity of the azoospermia factor (AZF) region in the Y chromosome. One of the second-generation females carrying FMR1 premutation was diagnosed with premature ovarian failure and another 3 with uterine myoma.

CONCLUSIONSSome of the FXS males in the pedigree may present macroorchidism and polyzoospermia but with normal semen parameters. In the intergenerational transmission, premutation might extend to full mutation, with even higher risks of transmission and extension of mutation in males, especially in those with >80 CGG triple repeat sequences. Therefore, it is recommended that the couples wishing for childbearing receive genetic testing, clinical guidance, and genetic counseling before pregnancy and, if necessary, prenatal diagnosis and preimplantation genetic diagnosis.

Chromosome Deletion ; Chromosomes, Human, Y ; genetics ; DNA Fragmentation ; Female ; Fragile X Mental Retardation Protein ; genetics ; Fragile X Syndrome ; genetics ; Genetic Testing ; Humans ; Infertility, Male ; genetics ; Karyotyping ; Male ; Mutation ; Organ Size ; Pedigree ; Pregnancy ; Preimplantation Diagnosis ; Risk ; Sex Chromosome Aberrations ; Sex Chromosome Disorders of Sex Development ; genetics ; Sperm Count ; Testis ; diagnostic imaging ; pathology

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 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

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

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