Excessive expansion of the CGG trinucleotide
repeat within the FMR1 gene on the X chromosome is the underlying genetic problem.
However, there are reports that the polymorphism level in trinucleotide
repeats is lower than that in di-nucleotide repeats for rice (Blair et al., 1999) and ryegrass (Jones et-al, 2001).
X-linked West syndrome is linked to mutations in the ARX which maps to Xp22.3 region.10 Guerinii et al reported that an expansion of a trinucleotide
repeat that codes for an expansion of the first polyA tract in six boys with infantile spasms, severe mental retardation, and dystonia.
This edition has a new chapter on genomics and personalized medicine, updated topics like gene identification, the genetics of common diseases, gene therapy, genomic imprinting, anticipation, and expanded trinucleotide
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We wondered if the same thing might be true of RNA," Al-Hashimi noted.To investigate that possibility, the researchers turned to a database of RNA structures and found that all structures with two helices linked by a particular type of junction called a trinucleotide
bulge fell along the same pathway.The team then went on to explore structures of RNA molecules with other kinds of junctions.
High resolution methylation analysis of the FMR1 gene trinucleotide
repeat region in fragile X syndrome.
An example is fragile X syndrome, which is the result of a trinucleotide
repeat expansion in one region of the genome that can result in autistic behavior, intellectual impairment, and seizures.
We used the GIS standard PCR conditions (above) with the following modifications: we used Tsg DNA polymerase (BioBasic) in place of BioTaq; we added 0.8 [micro]1 of 25 mmol [1.sup.-1] [Mgcl.sub.2] stock to the PCR cocktail (and adjusted and d[H.sub.2]0 amount accordingly); we labeled the 5' end of one forward primer with LI-OCR IRDye700 or IRDye800 infrared dyes; we diluted the 100 [micro]mol [1.sup.-1] labeled primer stock 1:99 in 10 [micro]mol [1.sup.-1] unlabeled primer (to reduce background signal); for one trinucleotide
(B105) we slightly increased the annealing temperature (58 [degrees]C) and reduced the [MgCl.sub.2] concentration (0.5 [micro]1) to reduce shadow banding.
Fragile X syndrome is associated with a large expansion of a variable region--the CGG trinucleotide
repeat within the 5' untranslated region--of the fragile X mental retardation--1 (FMR1) gene located on the X chromosome.
The genetic mutation underlying this disorder has been localized to the short arm of chromosome 4 and was found to consist of an expansion and instability of a polymorphic trinucleotide
repeat (CAG) in gene IT15.
Identification and sizing of the GAA trinucleotide
repeat expansion of Friedreich ataxia in 56 patients.
All microsatellites were characterized with the following descriptors: (i) complexity (simple/compound); (ii) motif (AAT, ATG, CA, etc.); (iii) type (perfect/imperfect); (iv) total repeats excluding non-repeat and half-repeat bases (TOTAL); (v) longest tandem repeat excluding half-repeats (MAX); (vi) repeat length including nonrepeat bases (LENGTH); (vii) non-repeat and half-repeat bases (NON); (viii) motif size (dinucleotide, trinucleotide
, etc.); (ix) number of terminal repeats (TER); (x) number of microsatellites amplified per primer-pair (NML); and (xi) expected PCR product size (PRO).