Chromosome instability syndromes are a group of disorders characterized by chromosomal instability and breakage. Recombination is a process that results in genetic exchange between chromosomes or chromosomal regions. Alternative splicing can be affected by various factors, including mutations such as chromosomal translocation. Polyploidy is an example of chromosomal mutation. The hereditary ataxias are categorized by mode of inheritance and causative gene or chromosomal locus. DQ2.5 refers to either a protein isoform and a genetic (chromosomal) haplotype. Microsatellites are used for assessing chromosomal DNA deletions in cancer diagnosis. CGH is only able to detect unbalanced chromosomal abnormalities. Typically, nuchal translucency alone is not sufficient as a screening test for chromosomal abnormalities. These are usually the product of a single gene with a specific chromosomal location. Uncapped telomeres also result in chromosomal fusions. Vinyl chloride is a mutagen having clastogenic effects which affect lymphocyte chromosomal structure. Telomeres compensate for incomplete semi-conservative DNA replication at chromosomal ends. In 1964, it was determined to be due to a chromosomal abnormality. DNA is examined from "microsatellites" within the chromosomal DNA.