In such cases, UDS is abnormal. Complementation testing means identifying the gene that is abnormal in the CS patient. A orCS group B gene defect and either has about the same overall effect on the patient's health. Knowing the affected gene could become in the future if protein or gene therapy became available, however. Injection of the same gene as is damaged in the patient results in more normal cellular behavior.
Normal behavior is seen only if the fused cells are affected in different genes.
CS cells would behave similarly if studied in the RNA synthesis inhibition assay instead. Mutational analysis is rarely performed by research laboratories interested in studying the different ways that CS genes may be damaged in CS patients. Researchers are interested in looking for relationships between the way the gene is damaged and the severity of the disease. CS patients from different families affected in the same CS gene are likely to have different damage occurring in the CS gene. Mutational analysis can be used to identify healthy relatives of CS patients who are carriers of the disease.