We hypothesised that at least some FLCN variants might erroneously appear as POPVs if detected in younger or smaller families with less chance of having manifested renal carcinomas and were not adequately followed-up (given that the median age at first pneumothorax was 34 years and median age at RCC was 47 years). The gene discussed is FLCN; the disease is renal cell adenocarcinoma.