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

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.

• Authors: F Rousseau
• Journal: European journal of clinical investigation (Eur J Clin Invest) Vol. 24 Issue 1 Pg. 1-10 (Jan 1994) ISSN: 0014-2972 [Print] England
• PMID: 8187801 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Review)

Chemical References

• Oligodeoxyribonucleotides

Topics

• Child
• DNA Mutational Analysis
• Female
• Fragile X Syndrome (diagnosis, genetics, prevention & control)
• Genetic Carrier Screening
• Genotype
• Humans
• Male
• Mass Screening
• Molecular Biology
• Oligodeoxyribonucleotides (genetics)
• Pedigree
• Phenotype
• Pregnancy
• Prenatal Diagnosis
• Repetitive Sequences, Nucleic Acid