A total of 2,970 EST-SSRs (2.38%) were identified by transcriptome sequencing of clam Meretrix meretrix (751,970 reads, ~310.82 Mbp), using 454 Genome Sequencer FLX next-generation sequencing platform. Dinucleotide SSR was the dominant repeat type (40.2%), followed by trinucleotide (37.8%), tetranuleotide (12.0%) and pentanucleotide (2.0%) SSR. The dominant repeat motif was AT (71.3%) in the di...

BACKGROUND Most patients with Friedreich ataxia (FRDA) have abnormal GAA triplet repeat expansions in both X25 genes. The size of the GAA expansion in the shorter of the 2 expanded alleles correlates significantly with parameters of clinical severity and is inversely related to the age at onset. OBJECTIVES To describe the clinical and molecular genetic findings in a patient with very late-ons...

Nucleic acid three-way junctions (3WJs) play key roles in biological processes such as nucleic acid replication in addition to being implicated as dynamic transient intermediates in trinucleotide repeat sequences. Structural modulation of specific nucleic acid junctions could allow for control of biological processes and disease states at the nucleic acid level. Trinucleotide repeat expansions ...

Expansion of (AGC)n repeats has been associated with genetic disorders called triplet-repeat diseases such as Huntington's disease (HD), myotonic muscular dystrophy (DM) and Kennedy's disease. To gain insight into the abnormal behavior of these repeats, we studied their structural properties in supercoiled DNA. Chemical probing revealed that, under physiological salt and pH conditions, Zn2+ or ...

Large-scale expansions of DNA repeats are implicated in numerous hereditary disorders in humans. We describe a yeast experimental system to analyze large-scale expansions of triplet GAA repeats responsible for the human disease Friedreich's ataxia. When GAA repeats were placed into an intron of the chimeric URA3 gene, their expansions caused gene inactivation, which was detected on the selectiv...

OBJECTIVE Friedreich's ataxia is the most common form of hereditary ataxia with autosomal recessive pattern. More than 96% of patients are homozygous for GAA repeat extension on both alleles in the first intron of FXN gene and the remaining patients have been shown to be heterozygous for a GAA extension in one allele and point mutation in other allele. MATERIALS & METHODS In this study, exons...

Expansion of trinucleotide repeats is associated with a growing number of human diseases. The mechanism and timing of expansion of the repeat tract are poorly understood. In humans, trinucleotide repeats show extreme meiotic instability, and expansion of the repeat tract has been suggested to occur in the germ-line mitotic divisions or postmeiotically during early divisions of the embryo. Studi...

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...