Apparent regression of the CGG repeat in FMR1 to an allele of normal size

Vits, Lieve; Boulle, Kristel De; Reyniers, Edwin; Handig, I; Darby, John; Oostra, Ben A.; Willems, Patrick J.

doi:10.1007/bf00211019

Cited by 30 publications

(13 citation statements)

References 23 publications

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“…In Figure 2 it is evident that, in transmissions from mothers in the 50-100 repeat range, the size of the repeat tends to increase steeply, but some contractions were also observed. The contraction of CGG repeat size is not unusual, and was reported in other studies Rousseau et al, 1991;Snow et al, 1993;Vits et al, 1994;Loesch et al, 1995], where reductions were observed within both the premutation and full-mutation ranges, or from full mutation to the premutation, or from the premutation to the normal range. Figure 2 also shows that for mothers with CGG values greater than 100, the number of repeats expands at a rate that seems independent of the size of the mother's CGG repeat.…”

Section: Exploratory Analysissupporting

confidence: 64%

Hierarchical Bayes model for random haplotype and family effects in the transmission of fragile‐X

Huggins

Loesch

Qian

et al. 2004

Genetic Epidemiology

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A model for the transmission of the CGG repeat sequence associated with the fragile-X dynamic mutation in the FMR1 gene is developed. The model incorporates both haplotype and family effects on the expansion rate of the sequence. The resulting random effects model is fitted to new data, using computer-intensive Markov chain Monte Carlo methods. The results demonstrate both the FRAXAC1-DXS458 haplotype and family effects on the transmission of CGG repeats from mother to offspring.

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Section: Exploratory Analysissupporting

confidence: 64%

Hierarchical Bayes model for random haplotype and family effects in the transmission of fragile‐X

Huggins

Loesch

Qian

et al. 2004

Genetic Epidemiology

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“…In fragile X syndrome, in which genotype-phenotype correlations have been thoroughly analyzed, at least 5 factors are known to affect the phenotypic expression of the mutation: sex of the affected individual, repeat length (including repeat contractions [159][160][161] ), the pattern of X-inactivation (for females), somatic cell mosaicism, and methylation status of the CpG island adjacent to the repeat. 162 These factors have a profound affect on the clinical phenotype and patterns of inheritance.…”

Section: Expansion Mutation and Nonmendelian Geneticsmentioning

confidence: 99%

Trinucleotide Repeat Expansion and Neuropsychiatric Disease

Margolis¹,

McInnis²,

Rosenblatt³

et al. 1999

Arch Gen Psychiatry

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Trinucleotide, or triplet, repeats consist of 3 nucleotides consecutively repeated (e.g., CCG CCG CCG CCG CCG) within a region of DNA, a not uncommon motif in the genome of humans and other species. In 1991, a new type of genetic mutation was discovered, known as a dynamic or expansion mutation, in which the number of triplets in a repeat increases and the length becomes unstable. During the past decade, nearly 20 diseases-including Huntington disease, 2 forms of the fragile X syndrome, and myotonic dystrophy-caused by trinucleotide repeat expansions have been identified. The unstable nature of the expanded repeat leads to remarkable patterns of inheritance in these diseases, distinctly at odds with traditional notions of mendelian genetics. We review the clinical and genetic features of these disorders, with a particular emphasis on their psychiatric manifestations. We also critically examine the hypothesis that expansion mutations may have an etiologic role in psychiatric diseases such as bipolar disorder, schizophrenia, and autism.

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“…Reduction of a premutation to a smaller premutation has been detected (6.7,15-17) as well as reduction of a premutation to a repeat length within the normal range (18). Decrease from a full mutation to a premutation has been reported only once (15), whereas the reverse mutation, from full mutation to a normal allele has not yet been described.…”

Section: Introductionmentioning

confidence: 99%

Hotspot for deletions in the CGG repeat region of FMR1 in fragile X patients

Graaff¹,

Rouillard

Willems

et al. 1995

Human Molecular Genetics

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The fragile X syndrome is the most frequent cause of inherited mental retardation. The molecular mechanism of the disorder is based on the expansion of a CGG repeat in the 5' UTR of the FMR1 gene in the majority of fragile X patients. The instability of this CGG repeat containing region is not restricted to the CGG repeat itself but expands to the flanking region as well. We describe four unrelated fragile X patients that are mosaic for both a full mutation and a small deletion in the CGG repeat containing region. Sequence analysis of the regions surrounding the deletions showed that both the (CGG)n repeat and some flanking sequences were missing in all four patients. The 5' breakpoints of the deletions were found to be located between 75-53 bp proximal to the CGG repeat. This suggests the presence of a hot spot region for deletions in the CGG repeat region of the FMR1 gene and emphasizes the instability of this region in the presence of an expanded CGG repeat.

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Apparent regression of the CGG repeat in FMR1 to an allele of normal size

Cited by 30 publications

References 23 publications

Hierarchical Bayes model for random haplotype and family effects in the transmission of fragile‐X

Hierarchical Bayes model for random haplotype and family effects in the transmission of fragile‐X

Trinucleotide Repeat Expansion and Neuropsychiatric Disease

Hotspot for deletions in the CGG repeat region of FMR1 in fragile X patients

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