ADAMTS13 and Opportunistic infection: Other studies have shown heterogeneity in levels of ADAMTS-13 in these patients ranging from very severe deficiency (< 5%) in up to 44% of patients to normal levels in up to 30% of patients and factors other than ADAMTS-13 deficiency are therefore postulated as pathogenic mechanisms including endothelial injury by HIV itself [21–25], damage by other opportunistic infections or endothelial activation caused by HIV-associated chronic inflammation [15, 18, 26].