ANALYSIS OF MUTATIONS IN THE GM-CSF RECEPTOR-ALPHA CODING SEQUENCE INPATIENTS WITH ACUTE MYELOID-LEUKEMIA AND HEMATOLOGICALLY NORMAL INDIVIDUALS BY RT-PCR-SSCP

Mutations of signal transducing molecules such as Ras have been shown to confer a growth advantage in leukaemic blasts and contribute to the pathogenesis of the disease. Alterations of signal transducing molecu les other than Ras may play a role in leukaemogenesis. Knowledge of su ch mutations could also further our understanding of the normal signal ling processes. We have therefore studied the coding sequence of the G M-CSF receptor alpha chain (GM-CSFR alpha) in patients with acute myel oid leukaemia (AML) and non-AML controls using single strand conformat ion polymorphism (SSCP) analysis. Abnormalities were detected in 4/32 AML patients (13%) and 2/15 non-AML controls (13%). Direct sequencing of PCR products revealed five different base substitutions. Three were conservative, two caused amino acid changes. The base substitution le ading to amino acid change alanine to glycine at position 17 was found in both an AML patient and a control. It lies in the signal sequence and does not affect the mature protein. The other base change altering arginine to glutamine at position 164 is unlikely to influence the re ceptor structure as this structural position in the chain is not well conserved in members of the cytokine receptor family. Both amino acid changes were constitutive alterations as they could be demonstrated in the patients' children. The base changes described in the AML patient s thus represent polymorphisms and do not contribute to the pathogenes is of AML.