The mutations responsible for several human neurodegenerative disorders are expansions of translated CAG repeats beyond a normal size range. To address the role of repeat context, we have introduced a 146-unit CAG repeat into the mouse hypoxanthine phosphoribosyltransferase gene (Hprt). Mutant mice express a form of the HPRT protein that contains a long polyglutamine repeat. These mice develop ...

The CAG repeats in the human Huntington's disease (HD) gene exhibit striking length-dependent intergenerational instability, typically small size increases or decreases of one to a few CAGs, but little variation in somatic tissues. In a subset of male transmissions, larger size increases occur to produce extreme HD alleles that display somatic instability and cause juvenile onset of the disorde...

Diseases associated with unstable repetitive elements in the DNA, RNA, and amino acids have consistently revealed scientific surprises. Most diseases are caused by expansions of trinucleotide repeats, which ultimately lead to diseases like Huntington's disease, myotonic dystrophy, fragile X syndrome, and a series of spinocerebellar ataxias. These repeat mutations are dynamic, changing through g...

Background: Trinucleotide repeats CAG (n) in androgen receptor gene is thought to be central to PCOS genetic susceptibility. However, previous studies of PCOS have shown variable association of CAG (n) polymorphism with PCOS. Objective: To assess the association of the AR gene CAG repeat length polymorphism with PCOS among Egyption patients, and its influence on clinical and biochemical androge...

CAG repeats occur predominantly in the coding regions of human genes, which suggests their functional importance. In some genes, these sequences can undergo pathogenic expansions leading to neurodegenerative polyglutamine (poly-Q) diseases. The mutant transcripts containing expanded CAG repeats possibly contribute to pathogenesis in addition to the well-known pathogenic effects of mutant protei...

Huntington disease (HD) is an autosomal dominant neurodegenerative disorder associated with expansions of an unstable CAG trinucleotide repeat in exon 1 of the IT15 gene. In normal individuals, IT15 contains up to 35 CAG repeats, while in affected the repeat length is >36. Polymerase chain reaction (PCR) is used to estimate the number of CAG repeats but may be inefficient in long repeats becaus...

Diseases such as Huntington's disease and certain spinocerebellar ataxias are caused by the expansion of genomic cytosine-adenine-guanine (CAG) trinucleotide repeats beyond a specific threshold. These diseases are all characterised by neurological symptoms and central neurodegeneration, but our understanding of how expanded repeats drive neuronal loss is incomplete. Recent human genetic evidenc...

I am Borut Peterlin, from Division of Medical Genetics, Department of Obstetrics and Gynaecology, University Medical Center, Ljubljana, Slovenia. We write to you to discuss if the number of CAG repeats in the androgen receptor (AR) gene is associated with male infertility in a group of 190 Slovene infertile men compared to 137 men with proven fertility. Pathophysiology of subfertility involves ...

Several disorders are caused by the genomic expansion of a trinucleotide repeat beyond a specific critical size in the coding region of genes. The largest group of these diseases, which includes Huntington’s disease and the spinocerebellar ataxias of type 1, 2, 3, 6, and 7, are caused by expansion of a CAG repeat resulting in proteins with an expanded polyglutamine stretch (14). A correlation b...

BACKGROUND We investigated the androgen receptor gene GGN polymorphism and its relation to male infertility and receptor function. METHODS Ninety-nine infertile patients with sperm counts < or = 5 x 10(6)/ml were screened for karyotypic abnormalities and Y-chromosome microdeletions. The GGN and CAG repeats were sequenced in those without genetic abnormalities and in 223 controls. RESULTS Fi...