Clinical predictors for germline mutations in head and neck paraganglioma patients: cost reduction strategy in genetic diagnostic process as fall-out.

Multiple genes and their variants that lend susceptibility to many diseases will play a major role in clinical routine. Genetics-based cost reduction strategies in diagnostic processes are important in the setting of multiple susceptibility genes for a single disease. Head and neck paraganglioma (HNP) is caused by germline mutations of at least three succinate dehydrogenase subunit genes (SDHx). Mutation analysis for all 3 costs approximately US$2,700 per patient. Genetic classification is essential for downstream management of the patient and preemptive management of family members. Utilizing HNP as a model, we wanted to determine predictors to prioritize the most heritable clinical presentations and which gene to begin testing in HNP presentations, to reduce costs of genetic screening. Patients were tested for SDHB, SDHC, and SDHD intragenic mutations and large deletions. Clinical parameters were analyzed as potential predictors for finding germline mutations. Cost reduction was calculated between prioritized gene testing compared with that for all genes. Of 598 patients, 30.6% had SDHx germline mutations: 34.4% in SDHB, 14.2% SDHC, and 51.4% SDHD. Predictors for an SDHx mutation are family history [odds ratio (OR), 37.9], previous pheochromocytoma (OR, 10.9), multiple HNP (OR, 10.6), age

Impact of screening kindreds for SDHD p.Cys11X as a common mutation associated with paraganglioma syndrome type 1.

CONTEXT AND OBJECTIVE: Germline mutations of the genes SDHB, SDHC, and SDHD predispose to paraganglioma syndromes. Mutation-specific counseling, risk assessment, and management recommendations ideally should be performed. Here, we provide data for a single common mutation of the SDHD gene. METHODS: The European-American Pheochromocytoma-Paraganglioma Registry served as the source for unrelated index cases affected by pheochromocytoma or paraganglioma. Patients with the SDHD c.33 C-->A (p.Cys11X) germline mutations were reinvestigated by whole-body magnetic resonance imaging and 24-h urinary catecholamine assay. First-degree relatives underwent genetic testing and those testing positive had same clinical investigations. Microsatellite analyses were used to test the hypothesis that all index cases were related and the mutation is a founding one. RESULTS: Sixteen index cases with the mutation SDHD p.Cys11X are registered. After testing their relatives, there were a total of 25 mutation carriers. We excluded seven subjects who inherited the mutation from the mother because of maternal imprinting. Thus, 18 mutation carriers were clinically affected. Among these 16 (89%) had head and neck paragangliomas, six (33%) thoracic tumors, six (33%) extraadrenal retroperitoneal, and five (28%) intraadrenal. Of note, 16 (89%) had multiple tumors at first diagnosis, and one (5%) had signs of malignancy during follow-up. Overall penetrance was 100% at age 54. Haplotype analyses revealed evidence for a founder effect. CONCLUSIONS: The SDHD p.Cys11X mutation is a founding mutation associated with a high penetrance for paraganglial tumors of the skull base, neck, thorax, and retroperitoneum in the first four decades of life and, rarely, with malignancy.

Interaction of single nucleotide polymorphisms in ADRB2, ADRB3, TNF, IL6, IGF1R, LIPC, LEPR, and GHRL with physical activity on the risk of type 2 diabetes mellitus and changes in characteristics of the metabolic syndrome: The Finnish Diabetes Prevention Study.

Single nucleotide polymorphisms (SNPs) in the ADRB2, ADRB3, TNF, IL6, IGF1R, LIPC, LEPR, and GHRL genes were associated with the conversion from impaired glucose tolerance (IGT) to type 2 diabetes mellitus (T2D) in the Finnish Diabetes Prevention Study (DPS). In this study, we determined whether polymorphisms in these genes modified the effect of changes in physical activity (PA) on the risk of T2D in the DPS. Moreover, we assessed whether the polymorphisms modified the effect of changes in PA on changes in measures of body fat, serum lipids, and blood pressure during the first year of the follow-up of the DPS. Overweight subjects with IGT (n = 487) were followed for an average of 4.1 years, and PA was assessed annually with a questionnaire. The interactions of the polymorphisms with changes in total and moderate-to-vigorous PA on the conversion to T2D during the 4.1-year follow-up were assessed using Cox regression with adjustments for the other components of the intervention (dietary changes, weight reduction). Univariate analysis of variance was used to assess interactions on changes in continuous variables during the first year of the follow-up. No interaction between the polymorphisms and PA on the conversion to T2D was found. The Leu72Met (rs696217) polymorphism in GHRL modified the effect of moderate-to-vigorous PA on changes in weight and waist circumference, the -501A/C (rs26802) polymorphism in GHRL modified the effect of total and moderate-to-vigorous PA on change in high-density lipoprotein cholesterol, and the Lys109Arg (rs1137100) polymorphism in LEPR modified the effect of total PA on change in blood pressure. In conclusion, genetic variation may modify the magnitude of the beneficial effects of PA on characteristics of the metabolic syndrome in persons with IGT.

Extra-adrenal and adrenal pheochromocytomas associated with a germline SDHC mutation.

BACKGROUND: A 46-year-old man presented with headaches, paroxysmal palpitations, anxiety and hypertension. The patient had undergone surgery for a retroperitoneal tumor at the age of 31 years, when histological examination revealed an extra-adrenal pheochromocytoma. The patient's 68-year-old mother had a history of a carotid body tumor, which had been resected when she was 34 years old. She was diagnosed with a meningioma at 54 years of age and a jugular paraganglioma at 68 years of age. INVESTIGATIONS: A 24h urine catecholamine assay was performed. CT imaging of the abdomen and (123)I-labeled metaiodobenzylguanidine scintigraphy revealed a right pheochromocytoma and left adrenal incidentaloma. An inherited neoplasia syndrome was suspected and molecular genetic analyses were performed. DIAGNOSIS: Right adrenal pheochromocytoma and left adrenal nonfunctioning incidentaloma, as part of a familial pheochromocytoma-paraganglioma syndrome associated with a germline mutation in SDHC (gene encoding succinate dehydrogenase complex, subunit C, integral membrane protein, 15 kDa). MANAGEMENT: Predictive testing, with genetic counseling. Management included surgical resection of the existing pheochromocytoma. The patient continues to be monitored with MRI scans of the neck, thorax, abdomen and pelvis every 1-2 years and an annual 24h urine collection for the measurement of metanephrines and catecholamines.

Ala12Ala genotype of the peroxisome proliferator-activated receptor gamma2 protects against atherosclerosis.

A mutation in the peroxisome proliferator-activated receptor gamma2 (PPARgamma2) gene with a cytosine to guanine substitution results in an exchange of proline (Pro) with alanine (Ala) in exon B (codon 12) of this gene. This polymorphism has been associated with high insulin sensitivity and low body weight, but no data have been published to date about its effect on early atherosclerosis. We investigated the relationship of the Pro(12)Ala polymorphism to early atherosclerosis, measured by the intima-media thickness (IMT). A total of 622 subjects were included, aged 40-70 yr, who were participants of the RIAD (Risk factors in Impaired glucose tolerance for Atherosclerosis and Diabetes) study and were at risk of developing type 2 diabetes. Altogether, 449 of the subjects had the common genotype (Pro(12)Pro), 162 had the Pro(12)Ala genotype, and 11 the Ala(12)Ala genotype. IMT was significantly decreased in subjects with the Ala(12)Ala genotype compared with subjects with the other two genotypes. Body mass index, free fatty acid levels, and leukocyte count were lower in subjects with the Ala(12)Ala genotype compared with subjects with the Pro(12)Pro or Pro(12)Ala genotypes. In multivariate analysis, the Ala(12)Ala genotype was a significant independent determinant of IMT. Furthermore, we demonstrated specific expression of the PPARgamma2 gene in human atherosclerotic lesions as well as in cultured primary macrophages and foam cells. In conclusion, our data suggest that the Ala(12)Ala genotype of the PPARgamma2 gene may protect from early atherosclerosis in subjects at risk for diabetes.

The G-250A promoter polymorphism of the hepatic lipase gene predicts the conversion from impaired glucose tolerance to type 2 diabetes mellitus: the Finnish Diabetes Prevention Study.

In population-based studies, dyslipidemia related to insulin resistance (high triglyceride level and low high-density lipoprotein cholesterol level) is a risk factor for type 2 diabetes. Therefore, variants in genes regulating lipid and lipoprotein metabolism are potential candidate genes for diabetes. We investigated whether the G-250A polymorphism of the hepatic lipase gene (LIPC) predicts the conversion from impaired glucose tolerance (IGT) to type 2 diabetes in the Finnish Diabetes Prevention Study. This study randomized subjects to either the intervention group (lifestyle modification aimed at weight loss, such as changes in diet and increased physical exercise) or the control group. Genotyping at position -250 of the LIPC gene was performed with PCR amplification, DraI enzyme digestion, and gel electrophoresis in 490 subjects with IGT whose DNA was available. In the entire study population, the conversion rate to type 2 diabetes was 17.8% among subjects with the G-250G genotype and 10.7% among subjects with the -250A allele (P = 0.032). In univariate analysis, the odds ratio for the G-250G genotype to predict the conversion from IGT to type 2 diabetes was 1.80 (95% confidence interval, 1.05-3.10; P = 0.034). In multivariate logistic regression analysis, the G-250G genotype predicted the conversion to diabetes independently of the study group (control or intervention), gender, weight, waist circumference at baseline, and change in weight and waist circumference. In the intervention group, 13.0% of subjects with the G-250G genotype and 1.0% of the subjects with the -250A allele converted to diabetes (P = 0.001). We conclude that the G-250G genotype of the LIPC gene is a risk factor for type 2 diabetes. Therefore, genes regulating lipid and lipoprotein metabolism may be potential candidate genes for type 2 diabetes.

The association of the K121Q polymorphism of the plasma cell glycoprotein-1 gene with type 2 diabetes and hypertension depends on size at birth.

Birth weight and length serve as indicators of the intrauterine environment, and a small body size at birth is a predictor of type 2 diabetes and hypertension. Insulin is one of the growth factors regulating fetal growth. The plasma cell glycoprotein 1 (PC-1) gene impairs insulin signaling at the insulin receptor level. Therefore, we investigated whether the K121Q polymorphism of the PC-1 gene association with insulin sensitivity, insulin levels, and the prevalence of diabetes and hypertension in adult life depends on size at birth in 489 subjects born in Helsinki during 1924-1933. We found that the effect of the PC-1 gene polymorphism on insulin levels and insulin sensitivity, measured as the homeostasis model assessment for insulin resistance, depended on birth length because fasting insulin levels and insulin resistance were highest in subjects carrying the 121Q allele who were small at birth (P for interaction = 0.04 and 0.05). Additionally, in those whose birth length was up to 49 cm, the K121Q polymorphism of the PC-1 gene was associated with a 2-fold higher incidence of type 2 diabetes. Moreover, subjects who were short at birth and who had the 121Q allele had the highest incidence (31.6%) of type 2 diabetes together with hypertension. We conclude that the interaction between the K121Q polymorphism of the PC-1 gene and birth length affects insulin sensitivity and increases susceptibility to type 2 diabetes and hypertension in adulthood.

Promoter polymorphisms of the TNF-alpha (G-308A) and IL-6 (C-174G) genes predict the conversion from impaired glucose tolerance to type 2 diabetes: the Finnish Diabetes Prevention Study.

High levels of cytokines are risk factors for type 2 diabetes. Therefore, we investigated whether the promoter polymorphisms of the tumor necrosis factor-alpha (TNF-alpha; G-308A) and interleukin 6 (IL-6; C-174G) genes predict the conversion from impaired glucose tolerance (IGT) to type 2 diabetes in the Finnish Diabetes Prevention Study. Altogether, 490 overweight subjects with IGT whose DNA was available were randomly divided into one of the two treatment assignments: the control group and the intensive, individualized diet and exercise intervention group. The -308A allele of the TNF-alpha gene was associated with an approximate twofold higher risk for type 2 diabetes compared with the G-308G genotype (odds ratio 1.80, 95% CI 1.05-3.09; P = 0.034). Subjects with both the A allele of the TNF-alpha gene and the C-174C genotype of the IL-6 gene had a 2.2-fold (CI 1.02-4.85, P = 0.045) higher risk of developing type 2 diabetes than subjects without the risk genotypes. We conclude that the -308A allele of the promoter polymorphism (G-308A) of the TNF-alpha gene is a predictor for the conversion from IGT to type 2 diabetes. Furthermore, this polymorphism seems to have a gene-gene interaction with the C-174C genotype of the IL-6 gene.

K121Q PC-1 gene polymorphism is not associated with insulin resistance in a Spanish population.

OBJECTIVE: To investigate the effect of the K121Q plasma cell membrane glycoprotein (PC-1) polymorphism on the components of the insulin resistance syndrome in a population-based nationwide multicenter study in Spain. RESEARCH METHODS AND PROCEDURES: The subjects of the study were 293 nonrelated adults (44.7% men and 55.3% women) ages 35 to 64 years randomly chosen from a nationwide population-based survey on obesity and related conditions, including insulin resistance and cardiovascular risk factors. Obesity-related anthropometric measurements included blood pressure, oral glucose tolerance test, lipid profile (total cholesterol, high-density lipoprotein- and low-density lipoprotein-cholesterol, and triglycerides), plasma leptin, insulin levels by radioimmunoassay, and insulin resistance (homeostasis model assessment). K121Q PC-1 genotypes were determined by restriction fragment-length polymorphism-polymerase chain reaction. RESULTS: Overall Q allele frequency was 0.14, with no differences between obese and nonobese individuals (0.15 vs. 0.13). After adjustment for sex, age, BMI, and degree of glucose tolerance, the Q allele was associated with high plasma leptin and triglyceride levels, but not with insulin resistance. DISCUSSION: The results showed that the K121Q PC-1 polymorphism in the Spanish population has no significant impact on insulin sensitivity.

The K121Q polymorphism of the PC-1 gene is associated with insulin resistance but not with dyslipidemia.

OBJECTIVE: To investigate the relationship of the K121Q polymorphism of the plasma cell glycoprotein 1 (PC-1) gene with insulin resistance, insulin secretion, and lipids and lipoproteins. RESEARCH DESIGN AND METHODS: Altogether, 110 normoglycemic subjects (group I) underwent a hyperinsulinemic-euglycemic clamp for evaluation of insulin sensitivity. The first-phase insulin secretion was determined by the intravenous glucose tolerance test (IVGTT) in a separate sample of 295 normoglycemic subjects (group II). RESULTS: The 121Q allele (genotypes K121Q and Q121Q) compared with the K121K genotype was related to higher fasting insulin levels (group I: 69.6 +/- 45.6 vs. 51.9 +/- 28.4 pmol/l [mean +/- SD], P = 0.050; group II: 66.6 +/- 38.8 vs. 53.8 +/- 26.6 pmol/l, P = 0.009). In group I, subjects carrying the 121Q allele compared with subjects with the K121K genotype had lower rates of whole-body glucose uptake (51.17 +/- 12.07 vs. 60.12 +/- 14.86 micro mol x kg(-1) x min(-1), P = 0.012) and nonoxidative glucose disposal (33.71 +/- 10.51 vs. 41.51 +/- 13.36 micro mol x kg(-1) x min(-1), P = 0.015) during the clamp. In group II, there was no significant difference between the 121Q allele carriers and subjects with the K121K genotype in total first-phase insulin secretion during the first 10 min of the IVGTT (2,973 +/- 2,224 vs. 2,520 +/- 1,492 pmol. l(-1). min(-1), P = 0.415). No association of the K121Q polymorphism with serum lipids and lipoproteins was found. CONCLUSIONS: In healthy normoglycemic Finnish subjects, the K121Q polymorphism of the PC-1 gene is associated with insulin resistance but not with impaired insulin secretion or dyslipidemia.

The C-174G promoter polymorphism of the IL-6 gene affects energy expenditure and insulin sensitivity.

Interleukin-6 (IL-6) is a pleiotropic cytokine expressed in many tissues. IL-6 null mice show low energy expenditure, but the effect of the variants of the IL-6 gene on energy expenditure has not been previously studied in humans. Therefore, we investigated the effect of the C-174G promoter polymorphism of the IL-6 gene on energy expenditure, measured by indirect calorimetry in healthy Finnish subjects (n = 124). We also measured insulin sensitivity by the hyperinsulinemic-euglycemic clamp. Subjects with the C-174C genotype of the IL-6 gene had significantly lower energy expenditure than subjects with the G-174C or G-174G genotypes both in fasting (CC 13.68 +/- 1.98, CG 14.73 +/- 1.57, GG 14.81 +/- 2.01 kcal x kg(-1) x min(-1); P = 0.012) and during the euglycemic-hyperinsulinemic clamp (CC 15.24 +/- 2.05, CG 16.62 +/- 2.06, GG 16.66 +/- 2.50 kcal x kg(-1) x min(-1); P = 0.007). Moreover, subjects homozygous for the C allele had lower rates of whole-body glucose uptake than carriers of the G allele (CC 50.95 +/- 13.91, CG 59.40 +/- 14.17, GG 59.21 +/- 15.93 micro mol x kg(-1) x min(-1); P = 0.016). The rates of both oxidative (P = 0.013) and nonoxidative (P = 0.016) glucose disposal were significantly affected by the IL-6 promoter polymorphism. In conclusion, the C-174C promoter polymorphism of the IL-6 gene influences energy expenditure and insulin sensitivity in healthy normoglycemic subjects. Whether this polymorphism is a risk factor for obesity or type 2 diabetes can be estimated only in prospective population-based studies.