Due to this increased risk, it is recommended that patients are screened for varicella zoster virus and antibody-negative patients are vaccinated prior to receiving treatment. In an analysis of post-approval data, as of 2020, no new infection safety signals were observed in over 18,000 patients.Progressive multifocal leukoencephalopathy has been reported in patients with hairy cell leukemia treated with parenteral cladribine. However, in up to 10 years of follow-up of patients receiving cladribine tablets for multiple sclerosis, no cases of progressive multifocal leukoencephalopathy have been observed; baseline MRI must be performed prior to initiating treatment.In clinical trials, malignancies were observed more frequently in patients treated with cladribine tablets compared with patients who received placebo. Compared with a matched reference population from the Global Cancer Observatory  database, cladribine tablets had no increased risk of malignancy in long-term real-world evidence data. Research directions
Cladribine has been studied as part of a multidrug chemotherapy regimen for drug-resistant T-cell prolymphocytic leukaemia. References
External links
"Cladribine". Drug Information Portal. U.S. National Library of Medicine.
False positives include other conditions with fatty infiltration of the ventricle, such as long-term excessive alcohol use and Duchenne or Becker muscular dystrophy. False negatives are common, however, because the disease progresses typically from the epicardium to the endocardium (with the biopsy sample coming from the endocardium), and the segmental nature of the disease. Also, due to the paper-thin right ventricular free wall that is common in this disease process, most biopsy samples are taken from the ventricular septum, which is commonly not involved in the disease process. A biopsy sample that is consistent with ACM would have > 3% fat, >40% fibrous tissue, and <45% myocytes. A post mortem histological demonstration of full thickness substitution of the RV myocardium by fatty or fibro-fatty tissue is consistent with ACM. Genetic testing
ACM is an autosomal dominant trait with reduced penetrance. Approximately 40–50% of ACM patients have a mutation identified in one of several genes encoding components of the desmosome, which can help confirm a diagnosis of ACM. Since ACM is an autosomal dominant trait, children of an ACM patient have a 50% chance of inheriting the disease-causing mutation. Whenever a mutation is identified by genetic testing, family-specific genetic testing can be used to differentiate between relatives who are at-risk for the disease and those who are not. ACM genetic testing is clinically available. Diagnostic criteria
There is no pathognomonic feature of ACM. The diagnosis of ACM is based on a combination of major and minor criteria.