POLYMORPHISM AT CODON-117 OF THE GRANULOC YTE MACROPHAGE COLONY-STIMULATING FACTOR GENE (GM-CSF)/

A T-to-C substitution, replacing a hydrophobic isoleucine residue with a hydrophilic threonine residue in position 100 of a mature protein m olecule, was found at codon 117 of the GM-CSF gene. The mutation frequ encies were estimated in 51 DNA samples from healthy adult donors and also in 20 samples from patients with different neoplastic myeloid dis orders. Almost equal substitution frequencies in patients and normal i ndividuals were observed, suggesting that the defect was not associate d with leukemia. Additionally the GM-CSF gene intron 1 sequence was re fined.