Clinical and genetic understanding of chromaffin tumors has been greatly enhanced in the last few years. Although some pheochromocytoma genes may still be unknown, the role of RET, VHL, SDHB, SDHD and NF1 genes is unequivocal and phenotypes are also being better characterized. The loss of function of VHL and NF1 genes can lead to a variety of tumors including phechromocytoma and their mechanism of action is under intensive investigation. Many different mutations are responsible for VHL gene inactivation but only missense mutations have been described so far in families with pheochromocytoma. Because of its large size extensive mutation analysis of the NF1 gene has seldom been performed, and mutations have only been identified in about 15% of patients. Several point mutations have been found in exon 31. Differences in pheochromocytoma phenotype in VHL or NF1 are not very pronounced, but it may be of some interest to consider the two groups separately. In VHL, pheochromocytoma has an earlier onset than in sporadic forms, it is often multiple, and malignancy is less frequent. The mean age of diagnosis is 28 years, the youngest patient being 5 years old. In NF1 patients pheochromocytoma phenotype is similar to sporadic forms. The mean age of pheochromocytoma onset is 42 years; 84% of patients have solitary adrenal tumors, 9.6% have bilateral adrenal disease and 6.1% have ectopic pheochromocytomas; malignant pheochromocytomas were identified in 11.5% of the cases. The group of pheochromocytoma susceptibility genes includes, along with the tumor suppressor genes VHL and NF1, the proto-oncogene RET and the genes encoding succinate dehydrogenase subunit D and succinate dehydrogenase subunit B. Whether there is a common pathway among these different genes is still a matter of debate.

Phaeochromocytoma is a tumour of the adrenal medulla, which, although rare, is a major cause of correctable hypertension with a prevalence of 0.1–0.5% in the hypertensive population. Clinical symptoms include attacks of paroxysmal headache, sweating, palpitations, stress and a sense of imminent death. Often associated with the above is an increase in blood pressure. Despite the fact that the underlying genetic mechanisms of phaeochromocytoma have been well investigated, they are still incompletely understood. In approximately 80% of cases the tumour occurs sporadically, but it may occur in association with type 2 multiple endocrine neoplasia, type 1 neurofibromatosis or von Hippel-Lindau disease. Molecular evidence suggests that other genes such as SDHD or SDHB may control its development; the possibility of other putative phaeochromocytoma genes is currently being investigated.

Growth hormone values after an oral glucose load do not addclinically useful information in patients with acromegaly on long-term somatostatin receptor ligand treatment. AbstractThe optimal method of assessing GH status in acromegalic patients receiving medical therapy with somatostatin analogs (SSA) has been matter of debate. The aim of the study has been to investigate whether OGTT may add information in patients with discordant random GH (GHr) and IGF values. Moreover, we evaluated the association of GH nadir with the prevalence of co-morbidities observed in acromegalic patients on SSA therapy. We evaluated 130 patients with proven diagnosis of acromegaly on SSA. The patients were subdivided in three groups: patients with controlled disease (both safe random GH and normal IGF-I, group A, 20.0 %), patients with uncontrolled disease (both high random GH and IGF-I, group B, 34.6 %), and patients with discordant random GH and IGF-I values (group C, 35.4 %). A high concordance rate for GH nadir with random GH and IGF-I was observed in group B, while a significant reduced concordance rate has been observed in group A (100 % sensitivity, 64.5 % specificity). By contrast, in group C, we observed concordant results between GH nadir and IGF