Screening for FMR1 expanded alleles in patients with Autism Spectrum Disorders in Manaus, Northern Brazil

Ferreira, Jorge; Batista, Jacqueline S.; Fantin, Cleiton

doi:10.1590/0001-3765201920180882

Cited by 3 publications

(2 citation statements)

References 37 publications

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“…The FMR1 (Fragile X messenger ribonucleoprotein 1) gene is located on the long arm of the X chromosome, at Xq27.3, where it encodes at least 12 different types of mRNA, originating from the alternative splicing method, with expression in several tissues, especially in the brain, testis, ovaries, and epithelium. The protein resulting from the expression of this gene is called FMRP (Fragile X messenger ribonucleoprotein 1) 1 .…”

Section: Introductionmentioning

confidence: 99%

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FMR1 alleles in women with idiopathic infertility

et al. 2022

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Introduction: The frequency of the premutated alleles of the FMR1 gene varies from 1: 100 to 1: 260 Israeli, Canadian, Finnish and American women, but it is unknown in Brazil. Premutation carriers may have reduced reproductive age and are at risk of transmitting the expanded allele to their offspring, and consequently fragile X syndrome. Objective: To observe the distribution range of the FMR1 gene alleles in a population of women with idiopathic infertility, without symptoms of premature ovarian insufficiency. Methods: The presence of premutation in FMR1 was assessed by conventional PCR, agarose and acrylamide gel and analysis of fragments in capillary electrophoresis. From the lymphocyte DNA obtained from 283 women undergoing infertility treatment. Results: It was observed that 169 patients had the normal heterozygous allele (59.7%), 114 had the normal homozygous allele (40.6%) and no patient had the premutation. Premature ovarian insufficiency is seen in 20 to 30% of women with the premutated allele. Thus, the condition can be asymptomatic in a large part of the premutation carriers. Brazil has a diverse population and, therefore, the allele frequencies of many gene variants are unknown. Previous Brazilian studies have shown a low frequency of the premutated allele in different patient cohorts. Corroborating these articles, the results demonstrated that the frequency of the premutated allele is low in the infertile women population studied. Conclusion: Tracking the size of the FMR1 gene alleles allows the expansion of knowledge about the frequency of risk alleles associated to genetic diseases in the Brazilian population.

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Section: Introductionmentioning

confidence: 99%

“…Premutation is considered to be the range of alleles between 55-200 repeats of CGG 1 . These alleles are unstable and can expand to full mutation when transmitted by a female.…”

Section: Introductionmentioning

confidence: 99%

FMR1 alleles in women with idiopathic infertility

et al. 2022

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Screening for FMR1 CGG Repeat Expansion in Thai Patients with Autism Spectrum Disorder

Hnoonual

Jankittunpaiboon

Limprasert

2021

BioMed Research International

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Autism spectrum disorder (ASD) is a complex disorder with a heterogeneous etiology. Fragile X syndrome (FXS) is recognized as the most common single gene mutation associated with ASD. FXS patients show some autistic behaviors and may be difficult to distinguish at a young age from autistic children. However, there have been no published reports on the prevalence of FXS in ASD patients in Thailand. In this study, we present a pilot study to analyze the CGG repeat sizes of the FMR1 gene in Thai autistic patients. We screened 202 unrelated Thai patients (168 males and 34 females) with nonsyndromic ASD and 212 normal controls using standard FXS molecular diagnosis techniques. The distributions of FMR1 CGG repeat sizes in the ASD and normal control groups were similar, with the two most common alleles having 29 and 30 CGG repeats, followed by an allele with 36 CGG repeats. No FMR1 full mutations or premutations were found in either ASD individuals or the normal controls. Interestingly, three ASD male patients with high normal CGG and intermediate CGG repeats (44, 46, and 53 CGG repeats) were identified, indicating that the prevalence of FMR1 intermediate alleles in Thai ASD patients was approximately 1% while these alleles were absent in the normal male controls. Our study indicates that CGG repeat expansions of the FMR1 gene may not be a common genetic cause of nonsyndromic ASD in Thai patients. However, further studies for mutations other than the CGG expansion in the FMR1 gene are required to get a better information on FXS prevalence in Thai ASD patients.

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