Molecular analysis of a rare folate-sensitive fragile site located at 19p13.1, FRA19B

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Mogk, Rhonda L.
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Expansions of p(CGG)n trinucleotide repeats have been identified as the underlying molecular etiology of rare folate sensitive fragile sites. Trinucleotide expansions of other repeat structures (CAG, GCG and GAA), while not associated with fragile sites, have also been implicated in various neurodegenerative diseases. Anticipation, defined as an increased severity and decreased age of onset in subsequent generations, is a hallmark of trinucleotide expansion diseases and has also been indicated in certain psychiatric disorders. Thus, it has been speculated that the molecular etiology of psychiatric disorders also involves trinucleotide expansions. Two families with the rare folate sensitive fragile site 'FRA19B ', located at 19p13.1, have been identified previously. Clinical phenotypes, including schizophrenia, autism and mental retardation, exist within one of these families; however, a clinical phenotype is not apparent in the second family. It is hypothesized that the molecular basis for 'FRA19B' is an expanded CG-rich trinucleotide repeat, which may affect a gene(s) important for normal mental function. Thus, molecular analysis of 'FRA19B' was undertaken in an attempt to identify: (1) the basis of chromosomal fragility at the 'FRA19B' locus and (2) a potential gene(s) within 'FRA19B'. (Abstract shortened by UMI.)