Evaluation of FMR1 gene mutations in Turkish women newly diagnosed with primary ovarian failure

Background: One of the known causes of ovarian dysfunction is fragile X mental retardation gene 1 (FMR1) premutation. The prevalence of FMR1 premutation in primary ovarian failure (POF) cases may differ between the studies due to some reasons including POF definition, definition of premutation, and determination of study population, ethnicity, genetic and environmental factors. In this study authors aimed to determine the prevalence of FMR1 mutations in patients who applied to present clinic and diagnosed as POF.Methods: This retrospective cohort study was conducted on 200 women who had been newly diagnosed with POF in present clinic between 2013 and 2014. The presence of cytogenetic fragility was firstly investigated in all patients by using the lymphocyte culture method, and molecular analysis of the FMR1 gene was then performed. Genomic DNA’s of cases were isolated using standard protocols, followed by polymerase chain reaction amplification with an appropriate program. Fragment analysis of the amplification products were performed by agarose gel electrophoresis.Results: Cytogenetic analysis results in 200 cases were numerically and structurally normal in all patients, and as a result of molecular genetic analysis of FMR1 gene; 1 (0.5%) patient had complete mutation and 9 (4.5%) patients had premutation carriage.Conclusions: FMR1 gene mutations are common in women with POF. These mutations should be investigated in all patients presenting with POF, particularly in cases with early onset and family history of POF, and also genetic counseling should be given to those patients.

Prenatal Population Screening for Fragile X Carrier and the Prevalence of Premutation Carriers in Korea

PURPOSE: Fragile X carrier detection before or at early pregnancy through a wide screening program may not only confer a risk of having offspring with Fragile X syndrome (FXS), but may also confer a risk for Fragile X-associated primary ovarian insufficiency and Fragile X-associated tremor/ataxia syndrome. However, prior to the implementation of such a program, the carrier prevalence in a population and the availability of effective screening test should be evaluated. The aim of our study was to determine the prevalence of premutation carriers and to evaluate the feasibility of screening test. MATERIALS AND METHODS: The blood samples were obtained from 8,641 pregnant women with no family history of mental retardation. We performed a three-primer CGG repeat primed (RP) PCR using the AmplideX(TM) FMR1 PCR kit (Asuragen, Inc. Austin, TX, USA). Samples showing full mutation alleles were reflexed to Southern blot analysis for methylation status and sizing. RESULTS: Among the 8,641 women, we found 8 premutation carriers (1:1,090, 0.09%) and 46 women with an intermediate allele (1:190, 0.53%). No woman was found to carry the fully mutated allele. All the detected alleles were within the CGG repeat range of 8-117. Among the 8,641 samples, 29 and 30 CGG repeats represent 66.6% of all cases. The CGG RP PCR method provides robust detection of expanded alleles and resolves allele zygosity, thus minimizing the number of samples that require Southern blot analysis. CONCLUSION: This is the first study that has focused on the prevalence of FXS premutation carriers and FMR1 allele distribution in normal pregnant women. These data have important implications for population-based fragile X carrier screening in Korea.

Prenatal Population Screening for Fragile X Carrier and the Prevalence of Premutation Carriers in Korea

PURPOSE: Fragile X carrier detection before or at early pregnancy through a wide screening program may not only confer a risk of having offspring with Fragile X syndrome (FXS), but may also confer a risk for Fragile X-associated primary ovarian insufficiency and Fragile X-associated tremor/ataxia syndrome. However, prior to the implementation of such a program, the carrier prevalence in a population and the availability of effective screening test should be evaluated. The aim of our study was to determine the prevalence of premutation carriers and to evaluate the feasibility of screening test. MATERIALS AND METHODS: The blood samples were obtained from 8,641 pregnant women with no family history of mental retardation. We performed a three-primer CGG repeat primed (RP) PCR using the AmplideX(TM) FMR1 PCR kit (Asuragen, Inc. Austin, TX, USA). Samples showing full mutation alleles were reflexed to Southern blot analysis for methylation status and sizing. RESULTS: Among the 8,641 women, we found 8 premutation carriers (1:1,090, 0.09%) and 46 women with an intermediate allele (1:190, 0.53%). No woman was found to carry the fully mutated allele. All the detected alleles were within the CGG repeat range of 8-117. Among the 8,641 samples, 29 and 30 CGG repeats represent 66.6% of all cases. The CGG RP PCR method provides robust detection of expanded alleles and resolves allele zygosity, thus minimizing the number of samples that require Southern blot analysis. CONCLUSION: This is the first study that has focused on the prevalence of FXS premutation carriers and FMR1 allele distribution in normal pregnant women. These data have important implications for population-based fragile X carrier screening in Korea.

Estudios de la región 5'UTR del gen FMR-1 en pacientes con falla ovárica prematura / Studies of the 5' - UTRTR region in the FMR-1 gene in patients withe Premature Ovarian Failure

La falla ovárica prematura (FOP) es un síndrome de patogénesis multicausal que afecta aproximadamente al 1% de las mujeres en edad reproductiva. Numerosos estudios asocian el estado de premutación (amplificación del número de tripletes CGG entre 50/55 y 200 repeticiones) en el gen FMR-1 y FOP. Alrededor de un 4% de las pacientes FOP presentan alelos con premutación. La amplificación del número de tripletes por encima de 200 repeticiones causa el Síndrome de Fragilidad del X (SFX). El objetivo del presente trabajo fue estudiar la región 5´ no codificante del gen en un grupo de pacientes FOP de Argentina. La región de interés se amplificó por PCR a partir de muestras de ADN de 100 pacientes FOP y 145 mujeres controles. Los alelos de las pacientes y controles fueron agrupados en 7 categorías de acuerdo al número de tripletes obtenidos. Se observó que el número de repeticiones más frecuente se encuentra en el rango de 26 a 30 tripletes, tanto en pacientes como en controles. En el grupo de pacientes FOP, 5/197 (2.6%) alelos no relacionados estudiados presentaron un número de tripletes CGG mayor a 50, mientras que sólo 1 de 290 (0.34%) para el grupo control. Todas las pacientes FOP con valores de tripletes CGG mayor a 50 presentaron amenorrea secundaria. Estos resultados están en concordancia con lo comunicado para otras poblaciones acerca de la existencia de una asociación entre la premutación del gen FMR-1 y el desarrollo de FOP. Asimismo, los resultados obtenidos refuerzan la importancia de la genotipificación del gen FMR-1 en las pacientes FOP, a los efectos de estimar el riesgo de su descendencia para el SFX.

Premature ovarian failure (POF) is a syndrome of multicausal pathogenesis that affects 1% of women before the age of 40. Several studies associate the premutation state (CGG repeats increased in number between 50/55 and 200) in the FMR-1 gene and POF. About 4% of POF women have alleles in the FMR-1 gene in the permutation range. An increase above 200 in the number of triplets in this gene causes the Fragile X Syndrome (FXS). The purpose of the present study was to analyze the 5´untranslated region of the FMR-1 gene in a group of patients from Argentina. The region of interest was amplified by PCR from DNA samples of 100 POF patients and 145 control women. Alleles from controls and patients were grouped in 7 categories according to the number of triplets obtained. We observed that the most frequent number of repeats ranged from 26 to 30 triplets, in both patient and control groups. In the POF group, 5 out of 197 (2.6%) not related alleles presented a number of CGG triplets higher than 50, while only 1 out of 290 (0.34%) was present in controls. All POF patients with a number of CGG repeats higher than 50 presented secondary amenorrhea. These results are in accordance with previous reports from other populations showing an association between the premutation state in the FMR-1 gene and POF development. In addition, these results reinforce the importance of genotyping POF patients to estimate the risk of their offspring for Fragile X Syndrome.

Dementia in Fragile X-associated Tremor/Ataxia Syndrome / Demência na síndrome de tremor-ataxia associada ao X-Frágil

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a cause of movement disorders and cognitive decline which has probably been underdiagnosed, especially if its prevalence proves similar to those of progressive supranuclear palsy and amyotrophic lateral sclerosis. We report a case of a 74-year-old man who presented with action tremor, gait ataxia and forgetfulness. There was a family history of tremor and dementia, and one of the patient?s grandsons was mentally deficient. Neuropsychological evaluation disclosed a frontal network syndrome. MRI showed hyperintensity of both middle cerebellar peduncles, a major diagnostic hallmark of FXTAS. Genetic testing revealed premutation of the FMR1 gene with an expanded (CGG)90 repeat. The diagnosis of FXTAS is important for genetic counseling because the daughters of the affected individuals are at high risk of having offspring with fragile X syndrome. Tremors and cognitive decline should raise the diagnostic hypothesis of FXTAS, which MRI may subsequently reinforce, while the detection of the FMR1 premutation can confirm the condition.

A síndrome de tremor-ataxia associada ao X-frágil (FXTAS) é uma causa de distúrbios do movimento e de declínio cognitivo que provavelmente tem sido subdiagnosticada, especialmente se a sua prevalência for realmente similar às da paralisia supranuclear progressiva e esclerose lateral amiotrófica. Relatamos um caso de um homem de 74 anos que se apresentou com tremor de ação, ataxia de marcha e esquecimento. Havia história familiar de tremor e de demência e um de seus netos era mentalmente deficiente. A avaliação neuropsicológica demonstrou uma síndrome frontal. A ressonância magnética (RM) revelou hiperintensidade de ambos os pedúnculos cerebelares médios, um critério maior para o diagnóstico de FXTAS. Os testes genéticos confirmaram a presença da pré-mutação do gene FMR1, com uma repetição (CGG)90. O diagnóstico de FXTAS é importante para o aconselhamento genético porque as filhas dos indivíduos afetados tem alto risco de ter uma criança com síndrome do X-frágil. A presença de tremores e declínio cognitivo deve levantar a hipótese diagnóstica de FXTAS, que poderá ser reforçada pela RM e confirmada pela presença da pré-mutação do gene FMR1.

Frequency of FMR1 premutation in individuals with ataxia and/or tremor and/or parkinsonism

A late onset neurological syndrome in carriers of premutation in FMR1 gene was recently described. The condition was named fragile-X-associated tremor/ataxia syndrome (FXTAS) and includes intentional tremor, cerebellar ataxia, parkinsonism, and cognitive deficit. We ascertained the contribution of FMR1 premutation to the phenotypes ataxia, tremor and/or parkinsonism. Sixty-six men over 45 years old presenting these symptoms, isolated or combined, were tested. Also, 74 normal men, randomly chosen in the population, formed the control group. In the patient group, no premutation carrier was found, which is in agreement with other observed frequencies reported elsewhere (0-5% variation). No significant differences were found when comparing gray zone allele frequencies among target and control groups. The FXTAS contribution in patients with phenotypic manifestations of FXTAS was 15/748 (2%). The presence of gray zone alleles is not correlated with FXTAS occurrence.

Fragile X screening for FRAXA and FRAXE mutations using PCR based studies: Results of a five year study.

Background: Fragile X syndrome is the most common cause of inherited X-linked mental retardation. It is due to a mutation in a gene on X chromosome leading to hyper-expansion of a trinucleotide repeat sequence. The two most common Fragile sites with clinical significance are FRAXA at Xq27.3 comprising CGG repeat and a more distal FRAXE associated with amplification of a GCC repeat, located at Xq28. The frequency of occurrence of Fragile X syndrome is estimated to be 1/4000 male births. Screening of referrals for the mutations associated with the Fragile X syndrome constitutes a significant workload in many genetic laboratories. Aims: The aim of the present study was to establish the use of PCR based simple and rapid method of initial screening of samples, so that only a minority of samples tested positive with the above methods need to be screened by Southern blotting which is more time consuming and involves use of radioactive material. materials and Methods: Study includes 294 patients with mental retardation. DNA extracted from blood was used for simultaneous amplification of the triplet repeat sequences at the FRAXA and FRAXE loci. Secondly samples from females were analyzed for heterozygosity of normal FRAXA allele. For confirmation of the presence of an expanded FRAXA allele in all the male positive cases, Southern blot hybridization was carried out. PCR based assay was done to detect methylation of the CpG island upstream of the FMR-1 gene. Results: Out of the 294 cases 23 (7.8%) were found to be having full mutation (FM) for FRAXA (21 males, 1 female & 1 male with mosaic FM/PM) and 13 females as having premutation (PM). All these 36 cases were confirmed by Southern blotting using appropriate probes. Among the females the heterozygosity for FRAXA allele was found to be 46%. Conclusion: Non-radioactive PCR methods are efficient and rapid test for intial screening of samples for the presence of FRAXA and FRAXE mutations. Since a large majority of referrals do not have Fragile X, this economical and reliable method reduces the number of samples needing Southern blotting.

Fragile X Premutation in Patients with Idiopathic Premature Ovarian Failure / 대한산부인과학회잡지

OBJECTIVE: To explore the incidence of fragile X premutation in patients with idiopathic premature ovarian failure, particularly in the Korean population. DESIGN: A prospective study. MATERIALS AND METHODS: Eighty-three women affected by idiopathic premature ovarian failure were recruited for this study. Patient with known causes of premature ovarian failure were excluded: cytogenetic abnormalities, prior chemotherapy, prior bilateral oophorectomy. DNA was extracted from peripheral blood. Fragile X (FRAXA) premutation was evaluated by PCR amplification of and Southern blot analysis for FMR1 gene. RESULTS: The FRAXA premutation was detected in three (3.6%) out of 83 patients with idiopathic premature ovarian failure. CONCLUSION: This result suggests that fragile X premutation screening is indicated in patients with idiopathic premature ovarian failure, particularly in the Korean population.