BACKGROUND AND INTRODUCTION Expansion of GAA triplet repeats in the first intron of the frataxin gene causes Friedreich's ataxia. Genetic testing in such condition is important to initiate the appropriate genetic counseling for the family members. The conventional genetic tests used in the diagnosis of Friedreich's ataxia are southern blot, short and long PCR. Recently, triplet repeat primed po...

enes harboring certain trinucleotide repeat (TNR) sequences are at risk for high-frequency mutations that expand or contract the repeat tract. The triplet sequences CNG (where N = any nucleotide) and GAA are known to cause human disease when they expand by more than a few repeats in certain key genes. One of the crucial questions in the field is the mechanism (or, more likely, mechanisms) of tr...

myotonic dystrophy (dm), one of the most common forms of muscular dystrophy, is an inherited disorder of the muscles and other body systems. dm is a progressive genetic disorder with a triplet repeat autosomal mutation that affects an estimated 1 in 8000 people. myotonic dystrophy type 1, also known as steinerts disease, and type 2 caused by mutation in dmpk and cnbp genes, respectively. in eac...

Nucleotide repeat instability is associated with an increasing number of cancers and neurological disorders. The mechanisms that govern repeat instability in these biological disorders are not well understood. To examine genetic aspects of repeat instability we have introduced an expanded CAG trinucleotide repeat into transgenic mice. We have detected intergenerational CAG repeat instability in...

Myotonic dystrophies or dystrophia myotonica (DM) is a clinical syndrome that includes myotonic dystrophy type 1 (DM1), myotonic dystrophy type 2 (DM2), myotonic dystrophy type 3 (DM3), and so forth. The terminology was recommended by the new nomenclature for myotonic dystrophies of an International Panel for Consensus. Previous studies have shown that DM1 is caused by the expansion of a cytosi...

In 1994, it was suggested that AGG interruptions affect the stability of the fragile X triplet repeat. Until recently, however, this hypothesis was not explored on a large scale due primarily to the technical difficulty of determining AGG interruption patterns of the two alleles in females. The recent development of a PCR technology that overcomes this difficulty and accurately identifies the n...

Hexanucleotide (GGGGCC) repeat expansion in C9ORF72 (HRE) causes frontotemporal lobar degeneration, frontotemporal dementia-amyotrophic lateral sclerosis, and amyotrophic lateral sclerosis. HRE was also seen in the genomes of patients suffering from several other degenerative diseases. However, whether it is present in the treatment-resistant schizophrenia patients remains unknown. Genotyping 3...

Expanded CAG repeat tracts are the cause of at least a dozen neurodegenerative disorders. In humans, long CAG repeats tend to expand during transmissions from parent to offspring, leading to an earlier age of disease onset and more severe symptoms in subsequent generations. Here, we show that the maintenance DNA methyltransferase Dnmt1, which preserves the patterns of CpG methylation, plays a k...