CPT® Code 88245

A chromosome analysis for breakage syndromes, as described by CPT® Code 88245, involves a specialized test known as Sister Chromatid Exchange (SCE). This analysis is crucial for identifying genetic abnormalities associated with breakage syndromes, which are conditions characterized by an increased susceptibility to chromosome breakage. Sister chromatids are the identical copies of a chromosome that are formed during DNA replication. The SCE test is particularly significant because exchanges between sister chromatids are infrequent under normal circumstances; however, certain environmental factors, such as exposure to specific chemicals, infectious agents, or physiological disorders, can elevate the frequency of these exchanges. The procedure utilizes peripheral blood lymphocytes, which are cultured in a separate, reportable procedure and stimulated to divide using a nonspecific antigen, such as phytohemagglutinin. To ensure that a sufficient number of cells are available for analysis, a spindle inhibitor is introduced to halt the cells in metaphase after a second mitotic division. This careful preparation allows for the observation of chromatid exchanges. Bromo-deoxy-uridine (BrdU) is incorporated into the culture medium for two complete cell cycles, facilitating differential staining of the chromatids. The staining process reveals dark Giemsa staining in chromatids with only one strand of DNA incorporated, while those with two strands exhibit lighter staining. If an exchange has occurred, the resulting chromosomes display a characteristic pattern known as harlequin chromosomes. This analysis is essential for diagnosing various breakage syndromes, including ataxia telangiectasia, Fanconi anemia, and fragile X syndrome, by providing insights into chromosomal integrity and function.