NORMAL MUTATION FREQUENCIES OF SOMATIC-CELLS IN PATIENTS RECEIVING GROWTH-HORMONE THERAPY

The number of reported cases of malignancy developing in growth hormon e (GH) users worldwide has increased to more than 40. However, the cau sal relationship between GH administration and the occurence of malign ancies is still uncertain. We investigated somatic cell mutation frequ encies (Mfs) or variant frequency (Vf) at three gene loci in patients with pituitary dwarfism receiving GH therapy to clarify the genetic ef fect of GH. Eighty-eight patients receiving GH therapy for at least 3 months and 42 age-matched healthy controls were studied. Mfs at hypoxa nthineguanine phosphoribosyltransferase (HPRT) and T-cell receptor (TC R) loci in GH users were not significantly higher than in the controls . Although a few patients seemed to have a slightly increased Vf at th e glycophorin A (GPA) locus, the difference was not statistically sign ificant. In addition, there was no tendency for the Mfs (Vf) at these loci to increase with the duration of the GH therapy. These data seem to exclude the possibility that GH induces genetic instability in pati ents with pituitary dwarfism who are receiving GH therapy.