Molecular analysis of mutations in the gene FMR-1 segregating in fragile X families
| Autor: | P. Steinbach, D. W�hrle, G. Tariverdian, I. Kennerknecht, G. Barbi, H. Edlinger, H. Enders, M. G�tz-Sothmann, H. Heilbronner, D. Hosenfeld, R. Kircheisen, F. Majewski, P. Meinecke, E. Passarge, A. Schmidt, H. Seidel, G. Wolff, M. Zank |
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| Rok vydání: | 1993 |
| Předmět: |
Male
Heterozygote Zygote DNA Mutational Analysis Restriction Mapping Gene Conversion Mothers Mutagenesis (molecular biology technique) Genes Recessive Nerve Tissue Proteins medicine.disease_cause Methylation Restriction fragment Embryonic and Fetal Development Fragile X Mental Retardation Protein Genetics medicine Humans Gene conversion Gene Genetics (clinical) X chromosome Repetitive Sequences Nucleic Acid Mutation biology Mosaicism Chromosomal fragile site RNA-Binding Proteins DNA medicine.disease Pedigree Fragile X syndrome Alternative Splicing Phenotype Gene Expression Regulation Mutagenesis Fragile X Syndrome biology.protein Female Polymorphism Restriction Fragment Length |
| Zdroj: | Human Genetics. 92:491-498 |
| ISSN: | 1432-1203 0340-6717 |
| DOI: | 10.1007/bf00216457 |
| Popis: | Molecular genetic analysis of the transmission of mutations in 73 families with fragile X (one of the largest samples evaluated so far) has confirmed previous hypotheses that the fragile X syndrome results from two consecutive mutational steps, designated "premutation" and "full fragile X mutation". These mutations give rise to expansions of restriction fragments, most probably by amplification of the FMR-1 CGG repeat. Premutations are identified by small expansions that apparently have no effect on either the clinical or the cellular phenotype. Full mutations are reflected by large expansions and hypermethylation of the expanded gene region. All males showing large expansions were affected. Individuals with full mutations also expressed the fragile X, with only one exception. An affected "mosaic" male, showing a predominance of premutated fragments in his leukocytes, was shown to be fragile-X-negative on different occasions. About 50% of heterozygotes with full mutations were reported by clinicians to be mentally retarded. Conversion of the premutation to the full mutation may occur at oogenesis, as previously suggested, or after formation of a zygote at an early transitional stage in development when the CGG repeat behaves as a mitotically unstable element on maternally derived/imprinted X chromosomes carrying a premutation of sufficient repeat length. |
| Databáze: | OpenAIRE |
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