CYP17A1 and Klinefelter syndrome: Family history, genetic factors (for example, BRCA gene carriers, AR and CYP17 gene mutation, Klinefelter syndrome, Cowden syndrome), exogenous oestrogen administration and testicular anomalies are among the risk factors [1-4,6], while radiation, obesity and alcohol use are proposed but not widely accepted as risk factors [2,3,6].