A novel menin gene deletional mutation in a little series of Italian patients affected by apparently sporadic multiple endocrine neoplasia type 1 syndrome.

AIM: To perform a genetic screening for the multiple endocrine neoplasia type 1 (MEN1) gene mutations in patients affected by an apparently sporadic form of the disease, referred to an internal medicine unit of a large general hospital. SUBJECTS AND METHODS: In a group of 12 consecutive patients presenting clinical features of MEN type 1 syndrome, we performed a genetic screening for germline MEN1 gene mutations, including complete sequencing of the coding region (exons 2 to 10) and multiplex ligation-dependent probe amplification analysis for large deletion detection. RESULTS: Among these patients affected by apparently sporadic MEN type 1 syndrome, a targeted clinical history could detect indirect support for a diagnosis of familial condition only in 2 cases. The genetic screening identified pathogenic germline MEN1 gene mutations in 3 patients (25%). A previously unknown 18 base-pair deletion within exon 3, c.564_581delCAATGGGGAGCAGACAGC, resulting in loss of 6 amino acids (pAsp189_Ala194del), was found in heterozygosis in a woman affected by primary hyperparathyroidism and multifocal pancreatic neoplasia. CONCLUSIONS: Our results underscore the importance of performing genetic testing also in apparently sporadic MEN1 patients and extend the list of molecular variants leading to inactivation of the MEN1 gene.

Genetic mutation screening in an italian cohort of nonsyndromic pheochromocytoma/paraganglioma patients.

To assess the prevalence of genetic mutations in nonsyndromic pheochromocytoma/paraganglioma (PHEO/PGL) patients we have performed a systematic search for mutations in the succinate dehydrogenase (SDH) B, C, and D subunits, von Hippel-Lindau (VHL), and RET genes by direct bidirectional sequencing. Patients were selected from the medical records of hypertension centers. After exclusion of syndromic patients, 45 patients with familial (F+, n=3) and sporadic (F-, n=42) cases of isolated PHEO/PGL were considered. They included 35 patients with PHEO, 7 with PGL, and 3 with head/neck PGL (hnPGL). Three patients with PHEO (2F-, 1F+) presented VHL mutations (P86A, G93C, and R167W), six with PGL (4F-, 2F+) were positive for SDH or VHL mutations (SDHB R230G in two patients, SDHB S8F, R46Q, R90Q, and VHL P81L in one subject each), and one with hnPGL carried the SDHD 348-351delGACT mutation. We have also detected missense (SDHB S163P, SDHD H50R and G12S), synonymous (SDHB A6A, SDHD S68S), and intronic mutations that have been considered nonpathological polymorphic variants. No mutation was found in SDHC or RET genes. Our data indicate that germline mutations of VHL and SDH subunits are not infrequent in familial as well as in sporadic cases of nonsyndromic PHEO/PGL (overall, 12 of 45 probands, 22%). Accordingly, screening for such mutations seems to be justified. However, a more precise characterization of the functional relevance of any observed sequence variant and of other genetic and environmental determinants of neoplastic transformation is essential in order to plan appropriate protocols for family screening and follow-up.

Blood pressure response to angiotensin II, low-density lipoprotein cholesterol and polymorphisms of the angiotensin II type 1 receptor gene in hypertensive sibling pairs.

Blood pressure (BP) response to infused angiotensin II (Ang II) has been widely used to characterize hypertensive subjects. High cholesterol levels have recently been found to enhance this response in young men, suggesting an important new link between atherosclerosis and hypertension. The present study assessed the familial resemblance of the BP response following an Ang II infusion and measured the factors affecting the trait in a large set of hypertensive men and women. After a low-salt diet for 7 days a 30-min infusion of Ang II was administered to 218 white hypertensive patients (28 singletons, 80 sibling pairs, 10 trios). Age and gender were significantly correlated to the Ang II systolic but not to the diastolic BP response. Conversely, cholesterol level and especially low-density lipoprotein (LDL) were correlated to both systolic and diastolic changes. Multivariate analysis showed that age, gender, and LDL were the three parameters that explained the systolic BP change whereas plasma LDL remained the only variable significantly correlated to the diastolic BP change. Significant familial resemblances in the Ang II induced systolic and diastolic BP response were observed, especially in female pairs. On this limited number of subjects, suggestive evidence for association and linkage was found between the trait, A1166C, and (CA)n repeat polymorphisms of the Ang II type 1 receptor (AT1R) gene. In conclusion, the Ang II induced BP change is strongly related to plasma LDL in hypertensive men and women, stressing the importance of the lipid profile as a contributor to BP regulation. Familial resemblance of this intermediate phenotype is sex dependent and may be partly explained by polymorphisms of the AT1R gene.

Aldosterone stimulation by angiotensin II : influence of gender, plasma renin, and familial resemblance.

The aldosterone response to infused angiotensin II (Ang II) in patients receiving a low-salt diet has been described as an important phenotype for genetic studies on human hypertension. The objectives of the present study were to determine the parameters that influence this intermediate phenotype as a quantitative trait and to assess the importance of its familial resemblance in hypertensive sibling pairs. Two hundred one white hypertensive subjects (95 families: 84 pairs and 11 trios) were selected in 3 centers. The patients followed the same protocol, which included a 4-week withdrawal period of antihypertensive therapy, a 1-week period on a low-salt diet, and a 30-minute infusion of Ang II. The increase in the aldosterone level was greater in women than in men (29.1+/-16.2 versus 18.2+/-9.6 ng/dL, P<0.0001). A strong relationship was found with age (r=-0.54, P<10(-4)) and plasma renin activity (r=0.32, P<10(-4)) in women but not in men. Weak correlations of the aldosterone response to Ang II were observed for the whole set of sibling pairs (r=0.11, NS). Conversely, strong sibling correlations were found among brother-brother pairs (r=0.40, n=36) and among sister-sister pairs as soon as age or menopausal status was considered. Similar results were obtained when the Ang I-aldosterone response was analyzed as a qualitative trait (kappa=0. 35, P<0.008 in brother-brother pairs). We conclude that age, gender, and plasma renin are strong determinants of the aldosterone response to Ang II, with strong sibling correlations in men and postmenopausal women. These relationships will have to be considered in future linkage and association studies.

Characterization of the binding of the RNA-binding protein AUF1 to the human AT(1) receptor mRNA.

An important mechanism of regulation of the expression of the AT(1) receptors is the modulation of the mRNA stability. AUF1, a human RNA-binding protein, may play an important role. Since AUF1 seems to bind to AU-rich regions of the 3'-untranslated region of the mRNAs, we verified the nucleotide sequence of human AT(1) receptor 3'-untranslated region and we found possible binding sites. In addition we evaluated the expression of the AUF1 protein in human vascular smooth muscle cells: the administration of both isoproterenol and angiotensin II induced a significant increase of total anti-AUF1 immunoreactive isoforms. At the same time angiotensin II induced a significant decrease in the AT(1) receptor mRNA abundance. Moreover, we found that recombinant human AUF1 protein binds to human AT(1) receptor riboprobes. The protein was able to bind to the distal portion of the 3'-untranslated region, and also to the coding region. Since the clinically relevant AT(1) receptor polymorphism is located in the 3'-untranslated region, we created two DNAs, corresponding to the A and C polymorphism, without any differences. Our data demonstrate the presence of AUF1 in human vascular smooth muscle cells and its modulation by activation of the beta-adrenergic and the AT(1) pathways, a and specific binding of AUF1 to the human AT(1) receptor mRNA, suggesting a role of this protein in the modulation of the AT(1) receptor expression.

Blood pressure evaluation by noninvasive and traditional methods. Consistencies and discrepancies among photoplethysmomanometry, office sphygmomanometry, and ambulatory monitoring. Effects of blood pressure measurement.

Three hundred eight outpatients referred for hypertension were studied. A continuous beat-to-beat noninvasive recording (Finapres) of blood pressure evaluated the blood pressure increase (9 mm Hg systolic and 4 mm Hg diastolic) induced by office sphygmomanometry. Thereafter, patients underwent a 24-h ambulatory blood pressure monitoring. The evaluation against Finapres showed that office sphygmomanometry overestimates the systolic blood pressure by 3 +/- 36 mm Hg (mean +/- 2 SD) and the diastolic blood pressure by 15 +/- 25 mm Hg (mean +/- 2 SD). Blood pressure monitoring showed similar discrepancies. On the basis of both monitoring (normalcy defined from a population of 550 normotensive subjects) and office sphygmomanometry, patients were considered normotensive, hypertensive (either untreated or under active drug treatment), white coat hypertensive (monitoring below the 95th percentile and sphygmomanometry more than 140/90 mm Hg, either untreated or under active drug treatment), and reverse white coat patients (monitoring over the 95th percentile and sphygmomanometry less than 140/90 mm Hg). Patients showed different levels of alert reaction (the highest in white coat hypertensive and the lowest in reverse white coat hypertensive patients), and a similar increase in blood pressure induced by conventional sphygmomanometry. During initial readings of ambulatory monitoring, blood pressure decreased from the first reading to the third reading. This decrease is related to the increase of blood pressure under sphygmomanometry. Caution should be paid in interpreting results of sphygmomanometry (error level in the single patient as high as +/- 40 mm Hg), and interpreting and averaging results of the first hour of blood pressure monitoring (variably affected by the alert reaction to the clinical environment).