Applications Of 24color Fish

Multicolor FISH (fluorescent in situ hybridization or 24-color FISH) is a molecular cytogenetic technique that uses fluorescent, combinatorially labeled, chromosome-specific DNA sequences to ''paint'' chromosomes to differentiate and classify nonhomologous pairs[1,2] (Fig. 1). This technique has been successfully applied to human chromosomes as well as to chromosomes of other mammalian species.[3]

The ability to visualize specific human chromosomes using fluorescent probes has been in existence since the 1980s.[4-6] What started as the application of radioactive nucleic acid probes for labeling chromosomes in the late 1960s[7] has now emerged into the possibility to simultaneously scan all of the 24 (22 autosomes and X, Y chromosomes) human chromosomes in defined fluorescent colors. Five fluorochromes are used to assign a spectral signature to each chromosome by combinatorial labeling of one to three fluorochromes for each chromosome using fluorochrome-specific filters and computer software.[1,2] This technique at different points in time has been given different names, e.g., 24-color FISH and Multifluor FISH (M-FISH), but 24-color FISH may be more appropriate. Similar to M-FISH is spectral karyo-typing (SKY), another multicolor technique that employs combinatorial labeling but uses, instead of filters, an interferometer to measure emission spectra specific for each chromosome.[1] The details of methods are provided elsewhere[8-10] and are published in this encyclopedia. Since its inception in 1996, 24-color FISH has become an important tool in clinical cytogenetics and has found a wide application in research as well.

Congenital Disorders and Prenatal Diagnosis

Chromosome aberrations substantially contribute to the genetic disease burden. For example, the prenatal frequency of de novo supernumerary marker chromosomes is around 1/2500 and it is estimated that de novo structural rearrangements occur with a frequency from 0.70/1000 rising to 2.4/1000 among mentally retarded individuals.1-11,12-1 In addition, deletions associated with defined phenotypic anomalies have been well documented for almost all major chromosome bands.[13] Balanced reciprocal translocations occur with a frequency of 1 in 600. The risk for unbalanced translocation, which are often associated with phenotypic abnormalities, in the progeny of balanced translocation carriers vary widely from 50% to <1%.[14] Complex chromosome rearrangements, although rare, are well documented; some cases involve as many as 10 breakpoints. The use of in situ hybridization and fluorescent DNA probes for the centromeres, locus-specific probes, and whole chromosome paint probes has facilitated the description of markers, derivative chromosomes, and complex karyo-types in much greater detail for prenatal and postnatal tissues. However, in certain situations when there is no strong clinical evidence pointing to the involvement of a particular chromosome, or when a marker of unknown origin or de novo derivative chromosome is encountered, the choice of individual probes to use is often a matter of trial and error. The introduction of 24-color FISH has now largely resolved this dilemma as each nonhomologous chromosome pair can be viewed in a unique color making it possible to identify and properly classify such chromosome aberrations with ease (Fig. 2). Detailed examples of such application of M-FISH are well documented and the literature is still growing.[9,15-18] For example, translocations between the sex chromosomes, which were beyond the resolution of standard G-banding, were identified by M-FISH in a male suspected Klinefelter syndrome.[15]

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

Get My Free Ebook

Post a comment