The aryl hydrocarbon receptor-interacting protein gene is rarely mutated in sporadic GH-secreting adenomas.

BACKGROUND: Recently, germline mutations of aryl hydrocarbon receptor-interacting protein (AIP) gene located on 11q13 were identified in patients with pituitary adenoma predisposition. AIM/PATIENTS AND METHODS: We investigated the involvement of the AIP gene in one family with isolated familial somatotropinomas (IFS). To investigate the role of AIP in sporadic GH-secreting adenomas, we first analysed somatic mutations in 40 tumours. Second, DNA from corresponding leucocytes was analysed in tumours showing genetic changes of the AIP gene. RESULTS: Germline mutation of AIP was found in an IFS family. Bi-allelic inactivation of AIP by a combination of germline mutation and loss of heterozygosity were confirmed in two pituitary adenomas. Mutation analysis of the AIP gene in the 40 sporadic GH-secreting adenomas showed no mutations except for a missense mutation, suggesting that germline mutations in patients diagnosed with sporadic acromegaly or gigantism were rare. In a patient with gigantism, a missense mutation of V49M was identified at the germline level. CONCLUSION: Based on these results, we conclude that the loss of function of AIP contributes to IFS, but not for most Japanese sporadic GH-secreting adenomas.

Genetic analyses in patients with familial isolated hyperparathyroidism and hyperparathyroidism-jaw tumour syndrome.

BACKGROUND: A subset of familial isolated primary hyperparathyroidism (FIHP) is a variant of hyperparathyroidism-jaw tumour syndrome (HPT-JT). AIM/PATIENTS AND METHODS: We investigated the involvement of the HRPT2, MEN1 and CASR genes in 11 provisional FIHP families and two HPT-JT families. RESULTS: Germline mutations of HRPT2 were found in two of the 11 FIHP families and one of the two HPT-JT families. One FIHP family with parathyroid carcinoma and atypical adenomas and another FIHP family with cystic parathyroid adenoma had novel frameshift mutations of 518-521del and 62-66del, respectively. In a patient with HPT-JT, a de novo germline mutation of 39delC was detected. Novel somatic HRPT2 mutations of 70-73del and 95-102del were found in two of five parathyroid tumours in a family with a 518-521del mutation. Biallelic inactivation of HRPT2 by a combination of germline and somatic mutation was confirmed in the parathyroid tumours. The finding that two families diagnosed with FIHP carried HRPT2 mutations suggests that they have occult HPT-JT. In the remaining 10 families, one family had a missense MEN1 mutation. No mutations of CASR were detected. CONCLUSION: Our results confirm the need to test for HRPT2 in FIHP families, especially those with parathyroid carcinomas, atypical adenomas or adenomas with cystic change.