Expansions of simple DNA repeats account for more than two dozen hereditary disorders in humans (for recent reviews see Lenzmeier and Freudenreich, Jin and Warren, Parniewski and Staczek, Ranum and Day, Brown and Brown, Cummings and Zoghbi, Bowater and Wells, and Siyanova and Mirkin). Table 1 describes those diseases and their important genetic features. Although originally discovered expansion...

Fuchs endothelial corneal dystrophy (FECD) is a common, familial disease of the corneal endothelium and is the leading indication for corneal transplantation. Variation in the transcription factor 4 (TCF4) gene has been identified as a major contributor to the disease. We tested for an association between an intronic TGC trinucleotide repeat in TCF4 and FECD by determining repeat length in 66 a...

Tandem repeats, that is simple sequence repeats, occur commonly in the human genome, and they have long been used as markers in linkage studies. In this decade, it has also been found that tandem repeats underlie an entirely new class of human mutations. The expansion of a group of trinucleotide repeats is now known to cause several inherited diseases, all of which are neurological disorders. T...

hereditary ataxias are heterogeneous group of neurodegenerative disorders classified mainly into more than 40 autosomal dominant cerebellar ataxias and 50 recessive ataxias. large amount of nearly uncommon subtypes with extensive phenotypic overlap and relatively high rate of abnormal repetitive sequence expansions, such as trinucleotide repeat expansions make diagnostic genetic testing complic...

Trinucleotide repeat disorders are a heterogeneous group of diseases caused by the expansion, beyond a pathogenic threshold, of unstable DNA tracts in different genes. Sequence interruptions in the repeats have been described in the majority of these disorders and may influence disease phenotype and heritability. Spinal bulbar muscular atrophy (SBMA) is a motor neuron disease caused by a CAG tr...

The human genome contains many simple tandem repeats that are widely dispersed and highly polymorphic. At least one group of simple tandem repeats, the DNA trinucleotide repeats, can dramaticallyexpand in size during transmission from one generation to the next to cause disease by a process known as dynamic mutation. We investigated the ability of trinucleotide repeats AAT and CAG to expand in ...

The majority of the human genome is comprised of non-coding DNA, which frequently contains redundant microsatellite-like trinucleotide repeats. Many of these trinucleotide repeats are involved in triplet repeat expansion diseases (TREDs) such as fragile X syndrome (FXS). After transcription, the trinucleotide repeats can fold into RNA hairpins and are further processed by Dicer endoribonuclases...

Triplex structure-forming GAA/TTC repeats pose a dual threat to the eukaryotic genome integrity. Their potential to expand can lead to gene inactivation, the cause of Friedreich's ataxia disease in humans. In model systems, long GAA/TTC tracts also act as chromosomal fragile sites that can trigger gross chromosomal rearrangements. The mechanisms that regulate the metabolism of GAA/TTC repeats a...