ARHGAP35 p.E25K was the only shared mutation of the 171coding mutations identified in tumours 1 and 3 of patient 5, which suggests two possibilities: (i) one of the two tumours was a metastasis of the other; or (ii) the two tumours arose independently, each acquiring an ARHGAP35 p.E25K mutation during cancer development. The gene discussed is ARHGAP35; the disease is cancer.