Cytogenetics

Molecular Cytogenetics

Molecular cytogenetics is a field that combines techniques from both molecular genetics and cytogenetics. It involves the use of various materials, such as DNA probes, that can recognize specific regions of our DNA. These probes help identify genetic abnormalities that cause diseases, including structural chromosomal disorders and the detection of gains or losses in genomic DNA.

One example of a molecular cytogenetics method is Fluorescence In Situ Hybridization (FISH), where DNA probes are labeled with different fluorescent colors to visualize one or more specific regions of the genome. FISH has several subtypes, each serving a different purpose:

Locus-Specific Probes: These probes are designed to bind to a specific region of a chromosome. The presence or absence of binding allows for the identification of any gain or loss in that region.

Chromosome-Specific Probes: These probes are a mixture of smaller probes that bind to different sequences along the length of each chromosome. In a technique known as Multicolor FISH (M-FISH), each chromosome can be tagged with a unique color, resulting in a fully colored karyotype. This method is particularly useful for studying chromosomal structural abnormalities. For example, if a fragment of one chromosome attaches to the end of another chromosome, it will be marked with two different colors, indicating a translocation.

Additionally, Microarray-Based Comparative Genomic Hybridization (a-CGH) is another method within molecular cytogenetics that can be used to detect chromosomal abnormalities and genomic imbalances. This technique involves comparing the DNA of a sample to a reference, allowing for the detection of duplications, deletions, and other genomic alterations.