Wild-type Subjects Research Articles

Polymorphism of the Vitamin D Receptor Gene, Bone Mineral Density, and Bone Turnover in Postmenopausal Women from Lower Silesia (Poland)

Genetic factors are involved in determining bone mineral density (BMD) and in the pathogenesis of osteoporosis. There are relationships between various genetic polymorphisms and BMD or bone turnover. The aim of our study was to assess polymorphisms in the vitamin D receptor (VDR) gene ( BsmI ) in relation to BMD and bone turnover in a group of Polish postmenopausal women from the Lower Silesia region. BMD at the lumbar spine and proximal femur, bone turnover (osteocalcin and carboxyterminal cross-linked telopeptide of type I collagen, ICTP), and restriction fragment length polymorphism (RFLP) of the VDR gene using the BsmI restriction enzyme were examined in 116 postmenopausal women. Despite the fact that we failed to detect statistically significant differences between the VDR genotypes in BMD, a trend towards higher BMD in women carrying allele b compared with wild-type subjects in our study is similar to previous reports. We also observed a higher allele b frequency in the control group (normal bone mass) compared with osteopenic/osteoporotic women (59.1% vs 40.0%). The lower activity of the resorption marker ICTP seen in allele b carriers could be involved. We report an association between VDR gene polymorphism and decreased BMD in Polish postmenopausal women from the Lower Silesia region, but this requires further robust studies for confirmation.

Sequence analysis of the ?-ADRENERGIC receptor (ADRA2B) gene and in-vivo functional effects of novel variants

Background ADRA2B is important in vasoconstriction and blood pressure regulation. The only common variant identified (del301–303) decreased receptor desensitization in vitro but did not alter vascular sensitivity in vivo. We therefore characterized the genetic variation in ADRA2B and related this to in vivo phenotype. Methods We examined 5812 bp of contiguous sequence of ADRA2B (promoter, exon, and 3' flanking region) using PCR and bidirectional sequencing (n=68). Vasoconstriction in response to the selective α2AR agonist dexmedetomidine (0.01–1000 ng/min) was measured in the dorsal hand vein using a linear variable differential transformer. ED50 and Emax were used to compare vascular responses in subjects with and without variant alleles. Results 27 variants were detected, including the previously described 301–303 deletion, 15 in the promoter region, 5 (2 non-synonymous) in the coding region and 7 in the 3'UTR region. Among the 9 variants with a minor allele frequency >5%, 3 SNPs (T1901G and G2572T in the promoter region and G4807A in the 3'UTR) were in linkage disequilibrium and associated with a lower Emax, 61.3±23.5% (mean±SD) compared to 77.8±17.0% in wildtype subjects, P= 0.048. There was no association between the 9 common variants and ED50. Conclusion We describe novel variants of the ADRA2B gene. These do not alter sensitivity to a selective α2AR agonist but may decrease maximal venoconstriction in vivo. Clinical Pharmacology & Therapeutics (2005) 77, P25–P25; doi: 10.1016/j.clpt.2004.11.095

Adenylate cyclase type 9 (AC9) polymorphism and in vivo vascular response

Background Adenylate cyclases (AC) catalyse the conversion of intracellular ATP to the second messager cyclic AMP. AC9 is the least well-characterized and most divergent of the nine AC isoforms. A common polymorphism in the AC9 gene, an Ile to Met at codon 772 due to an A to G substitution at bp 2312, resulted in reduced basal and beta-2 adrenergic receptor-stimulated AC activity in vitro. Prostaglandin (PG) E1 is a vasodilator that acts through stimulation of cAMP production. We hypothesized that the AC9 Met772 variant would result in impaired venodilation to PGE1 in vivo. Methods Vascular responses to PGE1 (2000 pg/min) infused into a phenylephrine-preconstricted dorsal hand vein were measured in 16 healthy subjects using a linear variable differential transformer. Venodilation was expressed as the percentage of reversal of the phenylephrine-induced constriction. Results Responses to PGE1 varied 13-fold among individuals (18% - 241%) but did not differ significantly in wild-type homozygotes (I/I, n= 5) and subjects carrying at least one variant Met772 allele (I/M, n= 8; M/M, n= 3) (84.8± 29.8 % versus 95.9± 68.9 %; P= 0.74). Conclusions These data suggest that the AC9 Met772 polymorphism is not associated with altered vasodilation in response to PGE1 in humans. Clinical Pharmacology & Therapeutics (2005) 77, P25–P25; doi: 10.1016/j.clpt.2004.11.097

Ile118Val genetic polymorphism of CYP3A4 and its effects on lipid-lowering efficacy of simvastatin in Chinese hyperlipidemic patients

To determine the frequencies of CYP3A4 alleles (CYP3A4*4,*5 and *6) in Chinese hyperlipidemic patients and to observe the impact of CYP3A4*4 (Ile118Val) genetic polymorphism on the lipid-lowering effects of simvastatin and on the activity of CYP3A4. From hospitalized and non-hospitalized patients, 211 unrelated hyperlipidemic patients were recruited for genotyping. CYP3A4 genotypes were determined by means of polymerase chain reaction and restriction fragment length polymorphism analysis. Of the non-hospitalized hyperlipidemic patients, 8 with CYP3A4*1/*1 and 8 with CYP3A4*1/*4 genotypes were selected to be treated with 20 mg simvastatin daily for 4 weeks. Serum triglycerides (TG), cholesterol (CHO) and low-density lipoprotein (LDL) levels were determined using an automated analyzer (Hitachi 747, Boehringer Mannheim, Mannheim, Germany). CYP3A4 activity was determined by the ratio of 6-hydroxycortisol to free cortisol (6-OHC/FC) in the morning spot urine with a high-throughput liquid chromatography-tandem mass spectrometry method. Of 211 subjects, 14 (allele frequency 3.32%) were heterozygous for CYP3A4*4 (Ile118Val). Nevertheless, no subjects with a CYP3A4*5 or CYP3A4*6 allele or homozygous for CYP3A4*4 were identified. The ratio of 6beta-OHC/FC was 9.9 +/- 13.7 and 56.6 +/- 35.7 in subjects with the Ile118Val variant (n = 8) and in CYP3A4 wild-type subjects (n = 8), respectively (P = 0.0039). After oral intake of simvastatin 20 mg daily for 4 weeks, the change of serum lipids in CYP3A4*1/*1 and CYP3A4*1/*4 groups showed a significant difference, with a mean decrease in triglycerides and total cholesterol of 38.1 +/- 7.6% versus 25.1 +/- 8.3% (P = 0.034) and of 35.8 +/- 9.6% versus 22.0 +/-20.4% (P = 0.0015) (means +/- SD), respectively. We found no statistically significant difference in the reductions of LDL between subjects carrying the *1 and *4 genotypes (29.0 +/- 7.4% versus 36.8 +/- 8.8%, P = 0.0721). The allele frequency of CYP3A4*4 was 3.32% among the hyperlipidemic patients from the Chinese mainland. CYP3A4*4 was an allelic variant related to a functional decrease of CYP3A4 activity, and *4 expression seemed to increase the lipid-lowering effects of simvastatin.

Toll–like receptor 4 gene Asp299Gly polymorphism is associated with reductions in vascular inflammation, angiographic coronary artery disease, and clinical diabetes

Background Coronary artery disease (CAD) and, increasingly, diabetes are recognized as having an inflammatory basis. Membrane toll-like receptors (TLRs) activate signaling pathways that up-regulate inflammation. We evaluated whether the Asp299Gly polymorphism in the TLR4 gene, which impairs inflammatory responses, is associated with reduced vascular inflammation (assessed by C-reactive protein [CRP]) and a decreased risk for CAD and diabetes. Methods 1894 patients without acute myocardial infarction undergoing coronary angiography were studied. Genotyping was performed by real-time polymerase chain reaction. CAD was defined as ≥70% stenosis. Diabetes was diagnosed by patients' referring physicians. CRP was measured by fluorescence polarization immunoassay. Regression analyses adjusted for traditional cardiac risk factors. Results Patients averaged 64 ± 11 years of age, and 69% were male. Asp299Gly genotype frequencies were: AA = 0.911 (n = 1725), AG = 0.086 (n = 164), and GG = 0.003 (n = 5), in keeping with Hardy-Weinberg equilibrium. CRP was lower among G-allele carriers (median = 1.11 mg/dL) than wild-type (AA) subjects (1.23 mg/dL, adjusted P = .044). G-allele carriers also had a lower prevalence of CAD (65% vs. 73%, OR = 0.67, CI = 0.46–0.99, adjusted P = .048) and diabetes (11% vs. 18%, OR = 0.63, CI = 0.42–0.95, adjusted P = .029), which persisted in multivariate logistic regression analyses. 299Gly carriage did not affect clinical outcomes nor interact with statin therapy. Conclusions The TLR4 299Gly allele was associated with reduced CRP levels and, in parallel, a decreased risk of angiographic CAD and clinical diabetes. These findings suggest that down-regulation of innate immune responsiveness could beneficially modify CAD and diabetes risk and might provide a novel basis for genetic risk stratification and therapeutic targeting.

Screening of 12 SNPs of CYP3A4 in a Chinese Population Using Oligonucleotide Microarray

Human cytochrome P450 3A4 (CYP34A) plays an important role in the metabolism of many endo- and xenomaterials. It also exhibits a substantial interindividual variation in enzymatic activity. It has been shown that the mutant alleles of CYP3A4 encoding inactive/decreased enzymes are largely caused by single nucleotide polymorphisms (SNPs) in the gene sequence. In the present study, with the goal of detecting the known SNPs of CYP3A4, an oligonucleotide microarray was created. A genotyping standard for this microarray was also established using constructed plasmids as standard templates. The 12 SNPs of CYP3A4 in 387 Chinese DNA samples were screened using this oligonucleotide microarray. Three heterozygous subjects of CYP3A4*/*4, 5 heterozygous subjects of CYP3A4*1/*5, 4 heterozygous subjects of CPY3A4*1/6, and 6 heterozygous subjects of CYP3A4*1/*18 were found. The genotyping results of the 18 heterozygous subjects and 12 wild-type subjects were validated by direct sequencing.

Functional analysis of single nucleotide polymorphisms of hepatic organic anion transporter OATP1B1 (OATP-C)

Two kinds of single nucleotide polymorphism (SNP; Asn130Asp and Val174Ala) are frequently observed in the liver specific transporter, organic anion transporting polypeptide 1B1 (OATP1B1/OATP-C) gene. Although these two SNPs occur independently in European-Americans, Val174Ala is mostly associated with Asn130Asp in Japanese. Our previous in-vivo studies in Japanese subjects indicated that the non-renal clearance of pravastatin was decreased to 13% of that in wild-type subjects (Nishizato et al. Clin Pharmacol Ther 2003;73(6):554-564). The purpose of the present study is to characterize the function of SNPs variants of OATP1B1 in cDNA transfected cells. The localization and transport activity were analyzed in HEK293 cells stably expressing wild-type OATP1B1 (OATP1B1*1a), OATP1B1*1b (Asn130Asp), OATP1B1*5 (Val174Ala) and OATP1B1*15 (Asn130Asp and Val174Ala). To characterize the intrinsic Vmax, observed Vmax in uptake study were normalized by the expression level estimated from Western blotting. All SNP variants are predominantly located on the cell surface. No significant alteration was observed in Km values for the transport of 17beta-estradiol 17beta-d-glucuronide (E217betaG), a typical substrate of OATP1B1, among these SNP variants. However, the normalized Vmax value for OATP1B1*15 was drastically decreased to less than 30% compared with OATP1B1*1a. In contrast, the transport activity of OATP1B1*1b (Asn130Asp) and OATP1B1*5 (Val 174Ala) was similar to that of OATP1B1*1a. These results are consistent with the results of our previous clinical studies. It is thus suggested that in-vivo disposition may be predicted from in-vitro results using recombinant transporters.

Effects of cytochrome P450 2C9 polymorphisms on phenprocoumon anticoagulation status

Our objective was to assess whether there is an association between the presence of allelic variants of the gene for cytochrome P450 (CYP) 2C9 and anticoagulation problems during the initial phase of phenprocoumon treatment. A prospective follow-up study was performed at 2 anticoagulation clinics in The Netherlands. Included subjects started phenprocoumon during the study period, had their first check of the international normalized ratio (INR) on the third or fourth day of therapy, and had an indication for the low therapeutic range (INR, 2.0-3.5). CYP2C9 genotypes ( CYP2C9*1 , CYP2C9*2 , and CYP2C9*3 ) were assessed, and data on indication, INR checks, comedication, and comorbidity were collected. After genotyping, 284 subjects were available for analysis. Of these, 186 (65.5%) were homozygous carriers of the CYP2C9 wild-type allele ( CYP2C9*1/*1 ), 61 (21.5%) were carriers of the CYP2C9*2 allele, and 37 (13.0%) were carriers of the CYP2C9*3 allele. Compared with homozygous CYP2C9*1/*1 subjects, carriers of CYP2C9*2 or *3 had an increased risk of severe overanticoagulation (INR >6.0). The hazard ratio for CYP2C9*2 versus CYP2C9*1/*1 was 3.09 (95% confidence interval [CI], 1.56 to 6.13; P=.001), and the hazard ratio for CYP2C9*3 versus CYP2C9*1/*1 was 2.40 (95% CI, 1.03 to 5.57; P=.042). Carriers of CYP2C9*2 also had a lower chance to achieve stability in the follow-up period. The hazard ratio for CYP2C9*2 versus CYP2C9*1/*1 was 0.61 (95% CI, 0.43 to 0.85; P=.003). Carriers of the CYP2C9*2 or *3 allele needed a significantly lower phenprocoumon dosage compared with homozygous CYP2C9*1/*1 subjects. The presence of at least 1 CYP2C9*2 or *3 allele in phenprocoumon users is associated with an increased risk of severe overanticoagulation. Similar to warfarin and acenocoumarol, phenprocoumon had a lower dosage requirement in carriers of CYP2C9*2 or *3 compared with that in CYP2C9 wild-type subjects.

Iron absorption by heterozygous carriers of the HFE C282Y mutation associated with hemochromatosis

Research conducted before genotyping was possible suggested that subjects heterozygous for the genetic mutation associated with hemochromatosis absorbed nonheme iron more efficiently than did control subjects when tested with a fortified meal. Heme-iron absorption in these subjects has not been reported. We compared the absorption of heme and nonheme iron from minimally or highly fortified test meals between HFE C282Y-heterozygous and wild-type control subjects. After prospective genotyping of 256 healthy volunteers, 11 C282Y-heterozygous and 12 wild-type control subjects were recruited, and their iron absorption was compared by using a hamburger test meal with or without added iron and ascorbic acid. After retrospective genotyping of 103 participants in previous iron-absorption studies, 5 C282Y-heterozygous subjects were compared with 72 wild-type control subjects. HFE C282Y-heterozygous subjects did not differ significantly from wild-type control subjects in their absorption of either heme or nonheme iron from minimally or highly fortified test meals. No differences were detected in blood indexes of iron status (including serum ferritin, transferrin saturation, and non-transferrin-bound iron) or in blood lipids or transaminases, but heterozygotes had significantly greater, although normal, fasting glucose concentrations than did wild-type control subjects. Compound heterozygotes (those who had both HFE C282Y and H63D mutations) absorbed more nonheme (but not heme) iron from meals with high (but not low) iron bioavailability. HFE C282Y-heterozygous subjects did not absorb dietary iron more efficiently, even when foods were highly fortified with iron from ferrous sulfate and ascorbic acid, than did control subjects. Iron fortification of foods should not pose an additional health risk to HFE C282Y heterozygotes.

Expression of the HFE hemochromatosis gene in a community-based population of elderly women.

Recent studies suggest that the clinical penetrance of associated hereditary hemochromatosis, defined as either the C282Y homozygote or compound heterozygote HFE genotype status, is much lower than previously thought. We investigated the clinical penetrance and phenotypic expression of HFE-associated hereditary hemochromatosis in a community-based population of 1352 elderly female subjects with a mean age of 75 years. Serum transferrin saturation and ferritin levels were determined on all subjects bearing a C282Y mutation and a subset of wild-type C282Y subjects. The prevalences of the C282Y homozygous and compound heterozygous HFE genotypes were 0.15% (2/1352) and 2.0% (27/1352), respectively. The observed prevalence of 0.15% for C282Y homozygotes borders on significance (P = 0.054) for deviation from the Hardy-Weinberg population equilibrium calculations, which predict a prevalence of 0.49%, whereas the observed and predicted compound heterozygote prevalences were not significantly different. Clinical symptoms of hemochromatosis were absent in both the C282Y homozygote subjects. Of the compound heterozygous subjects, 2/27 (7%) had elevated serum transferrin saturation and ferritin values; however, clinical symptoms of hemochromatosis were absent in both. Considered as a whole, the compound heterozygous subjects had markedly elevated means for serum iron (19.4 vs 16.0 micromol/L, P = 0.0008), transferrin saturation (34.8% vs 25.2%, P < 0.0001) and ferritin (157 vs 92 microg/L, P = 0.002) compared with the wild-type subjects. The C282Y homozygous HFE hereditary hemochromatosis genotype was under-represented in this elderly cohort, whereas the compound heterozygous genotype was not. None of the homozygous or compound heterozygous subjects expressed the phenotype of iron overload disease.

Mutation analysis of suppressor of cytokine signalling 3, a candidate gene in Type 1 diabetes and insulin sensitivity.

Beta cell loss in Type 1 and Type 2 diabetes mellitus may result from apoptosis and necrosis induced by inflammatory mediators. The suppressor of cytokine signalling (SOCS)-3 is a natural inhibitor of cytokine signalling and also influences insulin signalling. SOCS3 could therefore be a candidate gene in the development of Type 1 and Type 2 diabetes mellitus. Mutation analysis of the SOCS3 gene was performed in 21 patients with Type 1 diabetes mellitus and in seven healthy subjects. An identified promoter variant was examined in (i) 250 families with Type 1 diabetic family members (1097 individuals); (ii) 212 glucose-tolerant first-degree relatives of Type 2 diabetic patients; and (iii) 370 population-based young, healthy subjects who were unrelated. Three mutations were identified in the promoter region, but none in the coding region or the 3'UTR. Two of the three mutations had allele frequencies below 1% whereas the C -920-->A substitution had a minor allele frequency of 8%. In the group of young healthy subjects the insulin sensitivity index was higher among homozygous carriers of the A-allele than among heterozygous and wild-type subjects ( p=0.027, uncorrected). The same trend was found in the group of first-degree relatives of Type 2 diabetic patients. No association or linkage was found to Type 1 diabetes mellitus. Homozygosity for the A-allele of the C -920-->A promoter polymorphism of the SOCS3 gene may be associated with increased whole-body insulin sensitivity, but deserves further investigation.

Acenocoumarol stabilization is delayed in CYP2C93 carriers.

Our objective was to assess whether there is an association between the presence of allelic variants of the gene for cytochrome P450 (CYP) 2C9 and anticoagulation problems during the initial 3 to 6 months of acenocoumarol treatment. A prospective follow-up study was performed at 2 anticoagulation clinics in the Netherlands. Included subjects started with a standard dose regimen as follows: 6 mg on the first day, 4 mg on the second day, and 2 mg on the third day. CYP2C9 genotypes were assessed, and data on international normalized ratio (INR), comedication, and comorbidity were collected. The CYP2C9 genotype of 231 subjects was assessed. Of these, 147 (63.6%) were wild-type subjects (CYP2C9*1/*1), 38 (16.5%) were carriers of CYP2C9*2, and 46 (19.9%) were carriers of CYP2C9*3. Compared with wild-type subjects, carriers of the CYP2C9*3 allele had (1) a lower chance to achieve stability in the first 6 months of therapy (hazard ratio, 0.62; 95% confidence interval, 0.42-0.91; P <.05) and (2) an increased risk of severe overanticoagulation (INR >6.0) (hazard ratio, 3.80; 95% confidence interval, 1.54-9.39; P <.01). For both outcomes, there was no significant difference between carriers of the CYP2C9*2 allele and wild-type subjects. In carriers of the CYP2C9*3 allele more difficulties in terms of stabilization and overanticoagulation were found as compared with wild-type subjects or CYP2C9*2 carriers. CYP2C9 genotyping could be useful to identify potential candidates for more frequent INR controls to minimize problems with acenocoumarol anticoagulation status.

Evidence for inverse effects of OATP-C (SLC21A6) 5 and 1b haplotypes on pravastatin kinetics.

We compared the pharmacogenetic effects of OATP-C (organic anion transporting polypeptide C) *1a, *1b (A388G), and *5 (T521C) haplotypes on single-dose pharmacokinetics of pravastatin in white subjects. Thirty healthy white male subjects were grouped according to their OATP-C haplotype. Each group contained 10 individuals who were either homozygous or heterozygous carriers of the *1a, *1b, or *5 haplotype. After a single oral dose of 40 mg pravastatin, we analyzed kinetic parameters of pravastatin disposition. Values for the area under the plasma concentration-time curve from time 0 to 6 hours [AUC(0-6)] in *1a/*1a, *1a/*1b or *1b/*1b, and *1a/*5 individuals were 114.5 +/- 68.6 microg. L(-1). h, 74.8 +/- 35.6 microg. L(-1). h, and 163.0 +/- 64.6 microg. L(-1). h, respectively, with highly significant differences across all 3 study groups (P =.006) and between subjects carrying the *1b and *5 haplotype (P =.002). Strikingly, values of AUC(0-6) from the OATP-C *1b group were more than 60% lower than those derived from carriers of the wild-type OATP-C *1a haplotype, although this difference failed to reach statistical significance. However, the amount of pravastatin excreted into the urine from time 0 to 12 hours [Ae(0-12)] was significantly diminished in the OATP-C *1b haplotype group (1729 +/- 907 microg) compared with *1a wild-type control subjects (2974 +/- 1590 microg) (P =.049). There was a significant effect of tested OATP-C variant haplotypes on pravastatin disposition. Whereas *5 expression delayed the hepatocellular uptake of pravastatin, *1b expression seemed to accelerate OATP-C-dependent uptake of the drug.

Common polymorphisms in the glucocorticoid receptor gene are associated with adrenocortical responses to psychosocial stress.

Chronic dysregulation of hypothalamus-pituitary-adrenal axis activity is related to several stress-related disorders. Evidence suggests that polymorphisms in the glucocorticoid receptor (GR) gene may have an impact on this neuroendocrine system. In the present investigation, 112 healthy males were studied to estimate the impact of three GR gene polymorphisms (BclI RFLP, N363S, ER22/23EK) on cortisol and ACTH responses to psychosocial stress (Trier Social Stress Test) and pharmacological stimulation (1 microg ACTH(1-24), 0.5 mg dexamethasone). Because only four ER22/23EK heterozygotes were identified, these subjects were not statistically analyzed. Compared with subjects with the wild-type GR genotype (n = 36), 363S allele carriers (n = 10) showed significantly increased salivary cortisol responses to stress, whereas the BclI genotype GG (n = 18) was associated with a diminished cortisol response. BclI heterozygotes and homozygotes (GG) exhibited a trend toward lower ACTH responses, compared with wild-type subjects and 363S carriers. The cortisol response to ACTH(1-24) administration was not significantly different between genotypes. After dexamethasone ingestion, 363S carriers showed a trend toward an enhanced cortisol suppression. This is the first report documenting an impact of GR gene polymorphisms on cortisol (and perhaps ACTH) responses to psychosocial stress. These variants may contribute to the individual vulnerability for hypothalamus-pituitary-adrenal-related disorders.

A high prevalence of Gitelman's syndrome mutations in Japanese.

Although Gitelman's syndrome (GS) is considered a rare disorder, it is an autosomal recessive phenotype and the frequency of heterozygote subjects might be higher than suspected. The purpose of this study was to assess the prevalence of GS in Japanese and the effects of heterozygous GS mutations on blood pressure levels. We used the TaqMan system to detect 9 Gitelman's syndrome mutations in SLC12A3 that have been reported in Japanese. We then conducted association studies between these mutations and blood pressure in 1,852 subjects recruited from the Suita study, representing the general population in Japan. Among these 1,852 subjects, we detected the T180K, A569V, L623P, R642C, and L849H heterozygote genotypes in 56, 14, 1, 1, and 47 subjects, respectively. The overall frequency of GS mutations was (56+14+1+1+47) / (1,852 x 2) = 0.0321, which was much higher than suspected. This means we should expect to find one subject with a heterozygous GS mutation among 15.6 Japanese or that we should find 10.3 GS subjects among 10,000 Japanese. Although the blood pressure levels of subjects heterozygous for the T180K, A569V, or L849H genotype were not significantly different from those of wild-type subjects, urine pH in subjects with GS mutations was significantly higher than that in subjects without mutations. In conclusion, GS could be one of the major causes of low blood pressure in Japanese.

Heterozygous toll-like receptor 4 polymorphism does not influence lipopolysaccharide-induced cytokine release in human whole blood.

The heterozygous Asp299Gly mutation of the toll-like receptor (TLR) 4, the key receptor for lipopolysaccharide (LPS), has been associated with attenuated inflammatory responses. When 160 healthy volunteers (9% heterozygous and 0.6% homozygous) were genotyped and their LPS-inducible cytokine release was assessed in an ex vivo whole blood test, the responses of heterozygotes did not differ significantly from those of wild-type carriers for any of the cytokines (tumor necrosis factor-alpha, interleukin [IL]-1beta, IL-6, interferon-gamma, and granulocyte colony-stimulating factor) or eicosanoids measured or for serum cytokines and C-reactive protein. Ten heterozygous subjects and 12 wild-type control subjects responded similarly to a graded series of LPS and Escherichia coli concentrations, excluding the possibility that allele-specific differences are evident only at low stimulus concentrations or in response to whole pathogens. These data demonstrate that the heterozygous Asp299Gly polymorphism does not exhibit a functional defect in cytokine release after the stimulation of blood monocytes.

The relation between two polymorphisms in the glucocorticoid receptor gene and body mass index, blood pressure and cholesterol in obese patients.

We have recently reported that, in healthy elderly Dutch individuals, a N363S polymorphism in the glucocorticoid receptor (GR) gene is associated with higher sensitivity to low-dose dexamethasone (0.25 mg), evaluated as both cortisol suppression and insulin response, and with an increased body mass index (BMI). In the present study we investigated the role of the N363S polymorphism, and a BclI restriction site polymorphism in a group of Italian patients with severe obesity. Two hundred and seventy-nine patients (mean BMI 45.9 +/- 0.9 kg/m2) were genotyped using both PCR-restriction fragment length polymorphism analysis and Taqman Sequence Detection System. Determination of several metabolic and antropometric parameters was also performed in order to correlate them to the genotype. In this group of obese patients, 13 subjects (eight female, five males) were heterozygous for the N363S variant (allelic frequency 2.3%) and had significantly higher BMI (P < 0.04), resting energy expenditure (P < 0.03) and food intake (P < 0.01) when compared to wild-type homozygotes. When the data were analysed according to sex, female heterozygotes for the N363S allele had significantly higher BMI (P = 0.04), resting energy expenditure (P = 0.03) and food intake (P = 0.008) than obese women with the wild-type 363 GR gene. Male carriers of this variant also had higher values for these variables although the differences did not reach statistical significance. A case-control study with homozygous wild-type obese subjects which were age-, sex- and BMI-matched, revealed no difference in resting energy expenditure and food intake. The allele frequency of the BclI variant was 27% (89 females and 41 males out of 269 subjects). No differences in anthropometric and metabolic parameters were found between subjects heterozygous or homozygous for this variant GR in this obese population. However, when we studied the effect of the presence of the BclI polymorphism and the N363S variant in the same individual, we found that the subjects who carried both polymorphisms had a tendency towards higher systolic and diastolic blood pressure and significantly higher total and LDL-cholesterol levels (P = 0.005 and P = 0.05, respectively). Taking the results of this study and those obtained in the Dutch population, we speculate that heterozygous carriers of the N363S variant who develop obesity, may become even more obese, possibly because they have a hypersensitive insulin response and thus, via activation of lipogenesis, store fat more efficiently. Furthermore, these data suggest that N363S carriers who carry the BclI polymorphism as well, tend to have a slightly unfavourable cardiovascular profile.

A common NURR1 polymorphism associated with Parkinson disease and diffuse Lewy body disease.

NURR1 plays a key role in mesencephalic dopaminergic neuron development and survival. A homozygous NURR1 polymorphism (a single base-pair insertion in intron 6) (NI6P) has been reported to be associated with Parkinson disease (PD). To assess the association of the NI6P with PD and diffuse Lewy body disease. Case-control study. Movement disorders clinic and tissue provided by brain banks. Patients with pathologically proven PD (n = 37) or diffuse Lewy body disease (n = 35), neuropathologically normal control subjects (n = 59), those clinically diagnosed as having PD (n = 66), and spousal controls (n = 29). Determining the frequency of heterozygotes and homozygotes for the NI6P by DNA sequencing and restriction endonuclease analyses. Overall, 41 (39.8%) of the 103 patients with PD were heterozygotes compared with 22 (25.0%) of the 88 controls (P =.03), with a relative risk (estimated from the odds ratio) for PD of 2.03 (95% confidence interval, 1.08-3.81) for heterozygotes vs wild type subjects. Heterozygotes were more frequent in the subgroup of patients with pathologically confirmed PD (18 [48.6%] of 37) vs controls (14 [23.7%] of 59) (P =.01), with a relative risk for PD of 2.84 (95% confidence interval, 1.17-6.88) for heterozygotes vs wild type subjects. In patients clinically diagnosed as having PD, heterozygotes were more frequent in early-onset cases (onset at < or =45 years) (10 [55.6%] of 18) compared with late-onset cases (onset at >45 years) (10 [23.8%] of 42) (P =.02) or spousal controls (8 [27.6%] of 29) (P =.06), with a relative risk for early-onset PD of 4.17 (95% confidence interval, 1.13-15.33) for heterozygotes vs subjects with 2 wild type alleles. The homozygous NI6P was not associated with PD, but was present in 6 (17.1%) of the 35 patients with diffuse Lewy body disease compared with 3 (5.1%) of the 59 controls (P =.06). The common heterozygous NI6P is associated with an increased risk of PD. An association of borderline significance was found for the homozygous NI6P and diffuse Lewy body disease.

Contribution of variants in the small heterodimer partner gene to birthweight, adiposity, and insulin levels: mutational analysis and association studies in multiple populations.

Loss of function mutations in the small heterodimer partner (SHP) gene have been reported to cause obesity and increased birth weight. We examined the relation between genetic variation in SHP and birth weight, adiposity, and insulin levels in three independent populations. The coding regions and 562 bases of the SHP promoter were screened for mutations in 329 subjects with severe early-onset obesity. Two novel missense mutations, R34G and R36C, were identified; these were not found in control subjects and did not cosegregate with obesity in family studies. Two common polymorphisms, G171A and -195CTGAdel, were found in 12 and 16% of subjects, respectively. Within the obese cohort, G171A and -195CTGAdel carriers had higher and lower birth weights, respectively, than wild-type subjects, the rare homozygotes for G171A being particularly large at birth. In a U.K. population-based cohort of 1,079 children, the 171A allele was associated with higher BMI (P < 0.05) and waist circumference (P = 0.001). Children carrying the G171A variant had higher 30-min insulin responses to a glucose load (P = 0.03). In conclusion, although mutations in SHP are not a common cause of severe human obesity, genetic variation in the SHP locus may influence birth weight and have effects on BMI, possibly through effects on insulin secretion.

Association of polymorphisms in GPR10, the gene encoding the prolactin-releasing peptide receptor with blood pressure, but not obesity, in a U.K. Caucasian population.

Prolactin-releasing peptide (PrRP) and its G-protein-coupled receptor, GPR10, have been implicated in the central control of appetite and blood pressure. To determine whether mutations in these genes might contribute to morbid obesity, we screened both genes in 94 subjects with severe early-onset obesity. Four rare silent variants in PrRP and eight polymorphisms in GPR10 were found, two of which (V283I and P305L) altered amino acid sequence but were also found in U.K. Caucasian control subjects. Cells expressing the P305L variant receptor generated less intracellular calcium in response to PrRP than cells expressing the wild-type receptor. To examine whether genetic variation of the GPR10 locus might be associated with phenotypes relevant to obesity and/or blood pressure, the most common noncoding (G-62A) and coding (C914T [P305L]) polymorphisms were typed in 1,084 U.K. Caucasians. While no association was found with BMI, carriers of the P305L allelic variant had significantly lower systolic (123.95 vs. 128.55 mmHg, P < 0.05) and diastolic (74.90 vs. 78.20 mmHg, P < 0.01) blood pressure than wild-type subjects. In conclusion, we have conducted the first genetic study of GPR10 and its ligand PrRP in relation to metabolic phenotypes and have identified an association between GPR10 polymorphisms and diastolic and systolic blood pressure. The alteration in signaling properties of the receptor produced by P305L may provide a functional basis for this association.