In patients without a typical phenotype, notably young adult or adult women, in whom IGF-1 is measured due to a suspicious clinical scenario (1-5) and is found to be slightly elevated, even if confirmed and in the absence of other causes, a GH cut-off value of 0.4 μg/L (1,4,12-18) instead of 1 μg/L (3) in the OGTT might be inadequate for the diagnosis of acromegaly. The gene discussed is IGF1; the disease is acromegaly.