下垂体腺腫におけるGsα遺伝子変異の検討

概要

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Activating mutations of the Gsα protein coupled to the growth hormone-releasing hormone (GRH) receptor contribute to the genesis of growth hormone (GH)-secreting pituitary adenomas. However, the reported prevalence of these Gsα mutations in Japan varies considerably among institutions. We investigated the prevalence of the Gsα mutations in 133 pituitary adenomas, including 58 GH-secreting tumors, using RT-PCR and direct cDNA sequencing. Gsα mutations were present in 23 GH-secreting adenomas, but in none of the adenomas secreting other pituitary hormones or non-functioning adenomas. There were no significant differences in the age, sex, basal GH level, insulin-like growth factor-I (IGF-I) level, IGF-I SD score , or the basal prolactin level between the patient groups with and without Gsα mutations. The mean tumor volume was significantly smaller, and the GH or IGF-I/tumor volume ratio significantly higher, in the patients with the Gsα mutations. The GH response to GRH was significantly lower, while that to thyrotropin-releasing hormone (TRH) was significantly higher, in the patients with the Gsα mutations. These results demonstrate that Gsα mutations occur specifically in GH-secreting tumors, at a prevalence of 40%, and suggest that adenomas with these mutations may have a greater ability to produce GH per unit volume of the tumor.
東京女子医科大学の論文