To investigate the mechanism of the meiotic instability of expanded CAG repeats in the gene for Machado-Joseph disease (MJD1), we analyzed the CAG repeat sizes of 1036 single sperm from six individuals with Machado-Joseph disease (MJD). The segregation ratio between single sperm with an expanded allele and those with a normal allele is significantly different (P <0.0001) from the expected 1:1 s...

In its expanded form, the fragile X triplet repeat at Xq27.3 gives rise to the most common form of inherited mental retardation, fragile X syndrome. This high population frequency persists despite strong selective pressure against mutation-bearing chromosomes. Males carrying the full mutation rarely reproduce and females heterozygous for the premutation allele are at risk of premature ovarian f...

The mutational expansion of triplet repeat microsatellite sequences underlies the transmission of a number of heritable neurological disorders. However, this form of microsatellite instability has not previously been observed in association with malignant disease. Because trinucleotide expansions can dramatically alter gene expression and protein function, we hypothesized that they might occur ...

The mechanism of disease-associated trinucleotide repeat length variation may involve slippage of the triplet-containing strand at the replication fork, generating a slipped-strand DNA structure. We recently reported formation in vitro of slipped-strand DNA (S-DNA) structures when DNAs containing triplet repeat blocks of myotonic dystrophy or fragile X diseases were melted and allowed to reanne...

Myotonic dystrophy type 1 (DM1) is caused by DM protein kinase (DMPK) transcripts containing an expanded (CUG)n repeat. Antisense oligonucleotide (AON)-mediated suppression of these mutant RNAs is considered a promising therapeutic strategy for this severe disorder. Earlier, we identified a 2'-O-methyl (2'-OMe) phosphorothioate (PT)-modified (CAG)7 oligo (PS58), which selectively silences mutan...

Friedreich ataxia, the most common type of inherited ataxia, is itself caused in most cases by a large expansion of an intronic GAA repeat, resulting in decreased expression of the target frataxin gene. The autosomal recessive inheritance of the disease gives this triplet repeat mutation some unique features of natural history and evolution. Frataxin is a mitochondrial protein that has homologu...

Electronic effects were investigated on the singlet–triplet energy gaps of divalent unsaturated seven- membered ring R2C6H6M (M=C, Si, Ge, Sn, Pb, R= –H, -CH3, i-Pr , t-Bu) at B3LYP/6-311++G** level. All the triplet states of R2C6H6C were more stable than the related the singlet states while all the singlet states of R2C6H6M (M= Si, Ge, Sn, Pb, R= –H, -CH3, i-Pr , t-Bu) were more stable than th...

An important consideration in the development of a malaria vaccine for individuals living in areas of endemicity is whether vaccine-elicited immune responses can be boosted by natural infection. To investigate this question, we used Plasmodium berghei ANKA blood-stage parasites for the infection of mice that were previously immunized with a DNA vaccine encoding the P. berghei sexual-stage antig...