GSTM1 AND CYP2D6 GENOTYPE FREQUENCIES IN PATIENTS WITH PITUITARY-TUMORS - EFFECTS ON P53, RAS AND GSP

We describe studies to determine if susceptibility to pituitary tumour s is associated with the putatively high risk GSTM1 null and CYP2D6 EM genotypes. Frequency distributions of these genotypes were similar in cases and controls though the frequency of CYP2D6 PM and GSTM1 B tend ed to be lower (P = 0.072 and P = 0.095 respectively) in the tumour gr oup. Immunopositivity for p53 was found in 18/97 tumours. In these sam ples GSTM1 null (39%) and CYP2D6 EM (56%) frequencies were not differe nt to those in controls. The frequencies of CYP2D6 PM and GSTM1 B in t he p53 immunonegative tumours tended to be lower (P = 0.055 and P = 0. 1185 respectively) than in controls. Mutations in gsp and ras were stu died using the polymerase chain reaction and allele specific oligonucl eotide analysis. Eight of 19 somatotrophinomas demonstrated mutations in gsp; frequencies of GSTM1 null and CYP2D6 EM were similar to contro ls. No ras mutations were identified in 55-tumour studies. The data in dicate the GSTM1 null and CYP2D6 EM genotypes are not associated with altered expression of p53 or, mutation of gsp and ras in these adenoma s and, suggest the CYP2D6 PM genotype is associated with a reduced ris k of pituitary adenomas and, that GSTM1B confers greater protection t han GSTM1A.