Detailed histopathology was available for 59 of the tumours investigated: 18 of 43 (42%) RCC with a clear cell appearance had a somatic VHL gene mutation but none of 16 non-clear cell RCC (eight chromophilic, three chromophobe and five oncocytoma) (chi2 = 7.77, P < 0.025).(ABSTRACT TRUNCATED AT 250 WORDS)