<P> Multicolor FISH is used to identify structural chromosome aberrations in cancer cells and other disease conditions when Giemsa banding or other techniques are not accurate enough . </P> <P> Digital karyotyping is a technique used to quantify the DNA copy number on a genomic scale . Short sequences of DNA from specific loci all over the genome are isolated and enumerated . This method is also known as virtual karyotyping . </P> <P> Chromosome abnormalities can be numerical, as in the presence of extra or missing chromosomes, or structural, as in derivative chromosome, translocations, inversions, large - scale deletions or duplications . Numerical abnormalities, also known as aneuploidy, often occur as a result of nondisjunction during meiosis in the formation of a gamete; trisomies, in which three copies of a chromosome are present instead of the usual two, are common numerical abnormalities . Structural abnormalities often arise from errors in homologous recombination . Both types of abnormalities can occur in gametes and therefore will be present in all cells of an affected person's body, or they can occur during mitosis and give rise to a genetic mosaic individual who has some normal and some abnormal cells . </P> <P> Chromosomal abnormalities that lead to disease in humans include </P>

In humans twenty three chromosomes is what type of number