Detection of full fragile X mutation

Pergolizzi, Robert G.; Erster, Susan; Goonewardena, P.; Brown, W. Ted

doi:10.1016/0140-6736(92)91334-5

Cited by 79 publications

(39 citation statements)

References 8 publications

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“…Some recent papers have proposed using a PCR test for genotypic analysis at the fragile-)< locus [52,53]. Such a method has already been used to measure the exact number of CGG repeats of fragile X mutations with great precision [27,52]. It has the advantage of requiring smaller amounts of DNA but does not remove the burden of transferring the material under analysis onto a membrane and hybridizing it with a specific probe (as for a Southern blot).…”

Section: Dna Testingmentioning

confidence: 99%

“…Since the identification of fragile X mutations several genotyping protocols have been published [20,21,29,52,53]. Although fragile X mutations all affect the same target fragment, they are of many different types.…”

Section: Dna Testingmentioning

confidence: 99%

“…What physicians need to know is whether an individual carries a premutation or a full mutation (see genotype-phenotype correlations) because this greatly affects genetic counselling as well as follow up of the case. Some recent papers have proposed using a PCR test for genotypic analysis at the fragile-)< locus [52,53]. Such a method has already been used to measure the exact number of CGG repeats of fragile X mutations with great precision [27,52].…”

Section: Dna Testingmentioning

confidence: 99%

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The fragile X syndrome: implications of molecular genetics for the clinical syndrome

Rousseau

1994

Eur J Clin Investigation

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Abstract. The fragile X syndrome of mental retardation is one of the most common genetic diseases. Characterization of the mutations involved has greatly improved our knowledge of the transmission of fragile X syndrome and new DNA-based diagnostics tools significantly outperform cytogenetic testing both for establishing the diagnosis and for determining carrier status. Fragile X mutations consist of an expansion of a CGG trinucleotide repeat localized in a gene (FMR-1) that is abnormally methylated in all affected individuals. They are classified as premutations (asymptomatic) and full mutations (associated with the disease). Several different DNA analysis protocols are used for fragile X genotyping but only a few have been tested on large samples of individuals. There are several clinical indications for direct DNA genotyping for fragile X including mental retardation, learning disability or hyperactivity in children with or without a family history of mental retardation, the establishment of carrier diagnosis in fragile X families and prenatal screening of children from carrier women.

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Section: Dna Testingmentioning

confidence: 99%

Section: Dna Testingmentioning

confidence: 99%

Section: Dna Testingmentioning

confidence: 99%

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The fragile X syndrome: implications of molecular genetics for the clinical syndrome

Rousseau

1994

Eur J Clin Investigation

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“…The incidence of the fragile X syndrome is approximately one in 1000-2500 males (Herbst & Miller 1980, Turner et al 1986, Webb et al 1986). Unstable DNA sequence representing large increases in the number of CGG repeats have recently been located at the fragile site and characterization of the gene (FMR-1) implicated in the fra(X) syndrome is underway at several medical centers (Yu et al 1991, Oberle et al 1991, Verkerk et al 1991, Pergolizzi et al 1992. Alterations of the FMR-1 gene, detectable with several DNA probes with Southern blotting analysis and more recently with PCR methods, are gaining acceptance for diagnostic and clinical applications , Pergolizzi et al 1992).…”

Section: Introductionmentioning

confidence: 99%

Anthropometric and craniofacial patterns in mentally retarded males with emphasis on the fragile X syndrome

et al. 1993

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Anthropometric and craniofacial profile patterns indicating the percent difference from the overall mean were developed on 34 physical parameters with 31 white, mentally retarded males (23 adults and 8 children) with the fra(X) syndrome matched for age with 31 white, mentally retarded males without a known cause of their retardation. The fra(X) syndrome males consistently showed larger dimensions for all anthropometric variables, with significant differences for height, sitting height, arm span, hand length, middle finger length, hand breadth, foot length, foot breadth, and testicular volume. A craniofacial pattern did emerge between the two groups of mentally retarded males, but with overlap of several variables. Significant differences were noted for head circumference, head breadth, lower face height, bizygomatic diameter, inner canthal distance, ear length and ear width, with the fra(X) syndrome males having larger head dimensions (head circumference, head breadth, head length, face height and lower face height), but smaller measurements for minimal frontal diameter, bizygomatic diameter, bigonial diameter, and inner canthal distance. Several significant correlations were found with the variables for both mentally retarded males with and without the fra(X) syndrome. In a combined anthropometric and craniofacial profile of 19 variables comparing 26 white fra(X) syndrome males (13 with high expression (>30%) and 13 with low expression (< 30%), but matched for age), a relatively flat profile was observed with no significant differences for any of the variables. Generally, fra(X) syndrome males with increased fragile X chromosome expression have larger amplifications of the CGG trinucleotide repeat of the FMR-1 gene. No physical differences were detectable in our study between fra(X) males with high expression and apparently larger amplifications of the CGG trinucleotide repeats compared with those patients with low expression. Our research illustrates the use of anthropometry in identifying differences between mentally retarded males with or without the fra(X) syndrome and offers a comprehensive approach for screening males for the fra(X) syndrome and selecting those individuals for cytogenetic and/or molecular genetic testing. 1983, Meaney & Farrer 1986, Meaney & Butler 1989, Butler et al. 1991a. One of these conditions is the fragile X (fra(X)) or Martin-Bell syndrome, the most common familial cause of mental retardation. This syndrome is characterized by mental retardation, macroorchidism, large or prominent ears, a long narrow face, hyperflexibility and a characteristic chromosome fragile site at Xq27.3 (Turner et al. 1986, Hagerman 1987, Butler 1988. The incidence of the fragile X syndrome is approximately one in 1000-2500 males (Herbst & Miller 1980, Turner et al. 1986, Webb et al. 1986). Unstable DNA sequence representing large increases in the number of CGG repeats have recently been located at the fragile site and characterization of the gene (FMR-1) implicated in the fra(X) syndrome is under...

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“…Since then, attempts by various laboratories to improve on and automate this original method to detect larger CGG expansions or detect methylation status of CGG repeats was developed. Pergolizzi and coworkers [27][28][29][30][31] used deaza-dGTP in PCR in place of dGTP, however, because amplicons with deaza-dGTP cannot be stained by ethidium bromide, this method requires Southern blot analysis of amplicons, thus limiting its utility. The use of triplet-primed PCR (TP-PCR) for the detection of CGG expansion in FMR1 was initially described by Daniels et al, 32 who coined the term "repeat primer PCR."…”

mentioning

confidence: 99%

Qualitative assessment of FMR1 (CGG)n triplet repeat status in normal, intermediate, premutation, full mutation, and mosaic carriers in both sexes: Implications for fragile X syndrome carrier and newborn screening

Hantash

Goos

Tsao

et al. 2010

Genetics in Medicine

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Purpose: Fragile X syndrome is caused by expansion and subsequent methylation of a CGG trinucleotide repeat in the FMR1 5Ј-untranslated region. Southern blot analysis is typically required to determine expansion size for triplet repeat lengths Ͼ200. We describe a triplet-primed polymerase chain reaction-based method using automated capillary electrophoresis detection for qualitative assessment of expanded CGG repeats. Methods: The assay uses triplet-primed polymerase chain reaction in combination with GC-melting reagents and substitution of 7-deaza-2-deoxyGTP for dGTP. Amplicons are resolved by capillary electrophoresis. Results: A distinctive pattern of tapering or "stutter" polymerase chain reaction amplification was evident on capillary electrophoresis in male and female patients harboring all expanded allele lengths examined (up to 2000 CGG repeats) and could be used to differentiate normal, intermediate, premutation, and full mutation alleles. Full mutation alleles exhibited an additional late-migrating amplicon on capillary electrophoresis. Mixing experiments demonstrated sensitivity as low as 1% for detection of the full mutation allele. In a 1275-sample concordance study against our existing polymerase chain reaction platform (with Southern blot analysis for repeat lengths Ն55), the triplet-primed polymerase chain reaction method exhibited 100% concordance for normal, intermediate, expanded, and full mutation alleles. This method also detected the full mutation alleles in DNA isolated from blood spots. Conclusion: This assay provides an accurate assessment of FMR1 repeat status and holds promise for use in carrier and newborn screening. The method distinguishes normal homozygous females from full mutation carrying females. Although the method is not useful for accurate sizing, it supplements the classic polymerase chain reaction method and results in significant reduction in the number of Southern blot analyses required to be performed in the laboratory to accurately assess the FMR1 genotype in all individuals. Genet Med 2010:12(3):162-173.

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Detection of full fragile X mutation

Cited by 79 publications

References 8 publications

The fragile X syndrome: implications of molecular genetics for the clinical syndrome

The fragile X syndrome: implications of molecular genetics for the clinical syndrome

Anthropometric and craniofacial patterns in mentally retarded males with emphasis on the fragile X syndrome

Qualitative assessment of FMR1 (CGG)n triplet repeat status in normal, intermediate, premutation, full mutation, and mosaic carriers in both sexes: Implications for fragile X syndrome carrier and newborn screening

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