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Objective:APOE gene variants may contribute to the risk of chronic kidney disease. Our aim was to determine whether the common APOE-ε2/ε3/ε4 polymorphism is associated with a reduced estimated glomerular filtration rate (eGFR) in the RENASTUR population, a cohort of elderly individuals from the region Asturias (northern Spain). Methods: A total of 743 Spanish Caucasians aged 55-85 years were genotyped for the APOE-ε2/ε3/ε4 polymorphism. Individuals with a previous diagnosis of renal disease were not eligible for the study. Participants with a documented history of type 2 diabetes mellitus (T2DM) or hypertension or who were receiving antidiabetic or antihypertensive drugs were classified as diabetics and hypertensives. The eGFR was calculated using the Modification of Diet in Renal Disease formula, and those with an eGFR 2 (n = 91) were considered as having impaired renal function. The effect of alleles and genotypes on clinical (hypertension, T2DM) and analytical findings was statistically determined. Results: In addition to age and T2DM, APOE-ε2 was significantly associated with an eGFR 2 (p = 0.002; OR = 2.30). This association remained statistically significant after correction for multiple variables. Although the effect of the APOE-ε2 allele on the eGFR was observed both among diabetics and nondiabetics, the significance was stronger in the T2DM group. Conclusion: The APOE-ε2 allele is a genetic risk factor for impaired renal function among healthy elderly Spanish individuals.

MYH7 mutations are found in ∼20% of hypertrophic cardiomyopathy (HCM) patients. Currently, mutational analysis is based on the sequencing of the coding exons and a few exon-flanking intronic nucleotides, resulting in omission of single-exon deletions and mutations in internal intronic, promoter, and 3′ UTR regions. We amplified and sequenced large MYH7 fragments in 60 HCM patients without previously identified sarcomere mutations. Lack of aberrant PCR fragments excluded single-exon deletions in the patients. Instead, we identified several new rare intronic variants. An intron 26 single nucleotide insertion (−5 insC) was predicted to affect pre-mRNA splicing, but allele frequencies did not differ between patients and controls (n = 150). We found several rare promoter variants in the patients compared to controls, some of which were in binding sites for transcription factors and could thus affect gene expression. Only one rare 3′ UTR variant (c.*29T>C) found in the patients was absent among the controls. This nucleotide change would not affect the binding of known microRNAs. Therefore, MYH7 mutations outside the coding exon sequences would be rarely found among HCM patients. However, changes in the promoter region could be linked to the risk of developing HCM. Further research to define the functional effect of these variants on gene expression is necessary to confirm the role of the MYH7 promoter in cardiac hypertrophy.

An intronic single nucleotide polymorphism (SNP) in the CYP3A5 gene (CYP3A5∗3; SNP rs776746) affects RNA splicing and enzymatic activity. The CYP3A5∗3 frequency increased with distance from the equator and natural selection has been proposed to explain the worldwide distribution of this allele. CYP3A activity has been related with the risk for hypertension in pregnancy, a major cause of morbidity and mortality among women, and CYP3A5∗3 could reduce the risk for this disease in populations from regions with high sodium and water availability. The CYP3A5 genotype was related with blood pressure in the general population, but the effect on the risk for hypertension in pregnancy has not been evaluated. We compared the allele and genotype frequencies of three functional SNPs in the CYP3A5 (rs776746), CYP3A4 (rs2740574), and CYP21A2 (rs6471) genes between pregnant women who developed hypertension (n = 250) or who remained normotensive (control group, n = 250). In addition, we sequenced the full CYP3A5 coding sequence in 40 women from the two groups to determine whether some gene variants could explain the risk for hypertensive pregnancies in our population. Allele and genotype frequencies did not differ between hypertensive and normotensive women for the three CYP variants. We did not find CYP3A5 nucleotide changes that could explain a higher risk for hypertension in pregnancy. Our data suggests that the variation in CYP3A5, CYP3A4, and CYP21A2 did not contribute to the risk for hypertension in pregnancy in our population.

DNA variation at the FGF20 gene has been associated with Parkinson's disease (PD). In particular, SNP rs12720208 in the 3' untranslated region (3' UTR) was linked to PD-risk through a mechanism that would implicate a differential binding to microRNA-433 (miR-433). The reduction of the affinity of miR-433 to the 3' UTR would result in increased FGF20 expression and upregulation of alpha-synuclein, which could in turn promote dopaminergic neurons degeneration. We genotyped the rs12720208 SNP in a total of 512 PD patients and 258 healthy controls from Spain, and searched for miR-433 variants in the patients. We did not find significant differences in allele and genotype frequencies between patients and controls. None of the patients had miR-433 variants. In conclusion, our work did not confirm the association between rs12720208 and PD, or an effect of miR-433 variants on this disease.

Background: Gitelman’s syndrome (GS) is caused by mutations in the SLC12A3. Most of the mutations are rare, making it difficult to establish a genotype-phenotype correlation. Although GS is a recessive disorder, some patients also have an affected parent, suggesting a dominant inheritance. Methods: We sequenced the 26 coding exons of SLC12A3 in a family in which the proband and her father had a late onset GS. We obtained cDNA of the 2 patients and analyzed the effect of a mutation on pre-mRNA splicing. Results: The 2 patients were homozygous for a nucleotide change in the last nucleotide of exon 15: c.1925 G>A. The mother was a heterozygous carrier for this putative mutation. Amplification of cDNA with primers for exons 14–17 was negative, suggesting that this mutation affected the splicing and promoted mRNA degradation through nonsense-mediated decay. Conclusions: We report a family with 2 patients with late onset GS and homozygous for a mutation in the last nucleotide of exon 15. Our study shows that homozygosity for this mutation resulted in a significant loss of normal SLC12A3 transcript.

Arachidonate 5-lipoxygenase plays an important role in the synthesis of leukotrienes. Leukotrienes are inflammatory mediators, and inflammation has been implicated in the pathogenesis of Alzheimer disease. A polymorphism in the ALOX5 promoter consisting on 3 to 6 tandem-repeats of a Sp1/Egr1 binding motif (GGGCGG)n, has been related with the amount of gene expression. To verify the association between this polymorphism and the risk for late-onset Alzheimer disease we genotyped a total of 291 patients (mean age 74+/-7 y) and 300 controls (mean age 73+/-8 y). We found alleles of 3 to 6 repeats, and allele and genotype frequencies did not differ between patients and controls. These frequencies did not differ between patients according to the APOE genotype (epsilon 34 + epsilon 44 vs. epsilon 23 + epsilon 33). Together, our results indicate that the Sp1/Egr1-repeat polymorphism in the ALOX5 promoter is not a genetic marker for the risk of developing late-onset Alzheimer disease.

Background and aims Recent genomic surveys have identified IL12B as susceptibility locus for psoriasis (Ps). Our aim was to replicate the association between IL12B SNPs and Ps. In addition, we sequenced the IL12B gene in several patients to identify new variants that could explain the disease-risk. Results A total of 304 Ps-patients and 422 healthy controls (all Caucasian Spanish) were genotyped for three IL12B polymorphisms. SNP rs6887695 (GG genotype) was significantly associated with Ps (p = 0.002; OR = 1.60, 95% CI = 1.19–2.16). This genotype was also more frequent among patients with severe psoriasis (p = 0.03). Sequencing of 30 patients with the risk genotype identified several IL12B reported SNPs. Allele and genotype frequencies for two putative functional variants (rs3213120 and rs3213119) did not differ between patients and controls. Conclusions Our study confirmed rs6887695 as a risk factor for Ps. No other IL12B variants that could explain this association were found in our patients.

The Vaqueiros de Alzada are a human isolate from Asturias, a Northern Spain region. Several hypotheses have been proposed to explain the origin of Vaqueiros.To determine whether the Vaqueiros and non-Vaqueiros from the same region have different genetic backgrounds, this study analysed nine mtDNA polymorphisms that define the common European mitochondrial haplogroups in a cohort of Vaqueiros (n = 60) and non-Vaqueiros (n = 110). Haplogroup H was the most frequent in Vaqueiros (42%) and non-Vaqueiros (46%). A total of 37% Vaqueiros were H1, compared to 31% of the non-Vaqueiros. This study also genotyped the two groups for three polymorphisms at the NOS3. APOE and ACE genes, that have previously been linked to risk of cardiovascular diseases. Allele and genotype frequencies did not differ between Vaqueiros and non-Vaqueiros. In addition, none of these polymorphisms were related to risk of hypertension, diabetes or hypercholesterolaemia in the two groups.The data suggested that Vaqueiros share the main haplogroup distribution as their non-Vaqueiros neighbours and other Cantabrian populations. In addition, no effect of the mitochondrial, NOS3. APOE and ACE polymorphisms on cardiovascular risk factors was observed.

PRKN mutations have been linked to Parkinson’s disease (PD). Most of the mutational screenings have focused on the coding exons. The 3′ untranslated region (UTR) could also harbor functionally relevant nucleotide changes. We performed a mutational screening of PRKN in a cohort of early-onset PD patients (n = 235) from Spain. We found 16 mutations (five new): 16 patients (7 %) carried two mutations and only one mutation was found in 28 (12 %). Patients with two mutations had significantly lower mean age (30 ± 9 years) compared to patients with one (40 ± 7) or no mutation (42 ± 7). We found a total of 15 nucleotide variants (three new) in the 3′ UTR region. The frequency of carriers of the rare rs62637702 G allele (*94A/G) was significantly lower among the patients compared to healthy controls (n = 418) (0.03 vs. 0.004; p < 0.001), suggesting a protective role for this allele. In order to investigate the basal effect of this variant, we performed luciferase assays. No different basal activity was observed between the two alleles. In conclusion, the rs62637702 polymorphism was associated with PD. This could be a surrogate marker for disease risk, in linkage disequilibrium with other non-identified functional variant.

Mitochondrial dysfunction could contribute to the pathogenesis of psoriasis (Ps) and Ps-arthritis (PsA). Several common mtDNA polymorphisms/haplogroups have been linked to differences in the production of reactive oxygen species and mitochondrial oxidative damage. To test the hypothesis of an association between mtDNA variants and Ps/PsA, we studied the single-nucleotide polymorphisms that define the common European haplogroups in a total of 325 patients and 300 controls from Spain. No allele/haplogroup was significantly associated with the risk for Ps. However, haplogroup J was significantly less frequent among patients with PsA, suggesting a protective effect in our population (p=0.04; odds ratio=0.39). We concluded that mtDNA may have a role in Ps and PsA.

Alpha-synuclein gene (SNCA) polymorphisms have been associated with the common sporadic form of Parkinson’s disease (PD). We searched for DNA variants at the SNCA 3′ UTR through single strand conformation analysis and direct sequencing in a cohort of Spanish PD patients and controls. We have genotyped the rs356165 SNCA 3′ UTR polymorphism in a total of 1,135 PD patients and 772 healthy controls from two Spanish cohorts (Asturias and Navarre). We identified six SNCA 3′ UTR variants. Single nucleotide polymorphism (SNP) rs356165 was significantly associated with PD risk in the Spanish cohort (p = 0.0001; odd ratio = 1.37, 95%CI = 1.19–1.58). This SNP was also significantly associated with early age at onset of PD. Our work highlights rs356165 as an important determinant of the risk of developing PD and early age at onset and encourages future research to identify a functional effect on SNCA expression.

MicroRNAs (miRNAs) are small RNAs that bind to mRNAs and regulate gene expression. MyoMirs are miRNAs implicated in cardiogenesis. Some MyoMirs have been found deregulated in hearts from patients with left ventricular hypertrophy (LVH). DNA variants at these miRNAs could contribute to the risk of developing hypertrophic cardiomyopathy (HCM). To test this hypothesis we used single strand conformation analysis and direct sequencing to search for DNA variants in the mir-208a, miR-208b, miR-133a-1, miR-133a-2, miR-133b, miR-1-1, and miR-1-2 genes in patients with HCM (n=245), LVH secondary to hypertension (n=120), and healthy controls (n=250). We found several nucleotide variants. Genotyping of patients and healthy controls showed significantly associations between a 133a-1 polymorphism and HCM and a 133b polymorphism and hypertensive- LVH. We concluded that rare variants in these mature miRNAs would be rarely found among HCM patients, but miR-133a-1 and 133b polymorphisms could contribute to the risk of developing cardiac hypertrophy.

Mitochondrial dysfunction could contribute to the development of spastic paraplegia. Among others, two of the genes implicated in hereditary spastic paraplegia encoded mitochondrial proteins and some of the clinical features frequently found in these patients resemble those observed in patients with mitochondrial DNA (mtDNA) mutations. We investigated the association between common mtDNA polymorphisms and spastic paraplegia. The ten mtDNA polymorphisms that defined the common European haplogroups were determined in 424 patients, 19% with a complicated phenotype. A rare haplogroup was associated with the disease in patients without a SPG3A, SPG4, or SPG7 mutation. Allele 10398G was more frequent among patients with a pure versus complicated phenotype. This mtDNA polymorphism was previously associated with the risk of developing other neurodegenerative diseases. In conclusion, some mtDNA polymorphisms could contribute to the development of spastic paraplegia or act as modifiers of the phenotype.

Mutations in the beta-amyloid precursor protein gene (APP) have been found in familial early-onset Alzheimer’s disease (AD). DNA variants at several genes have been linked to the risk of developing the most common late-onset form of AD (LOAD). A few studies analyzed the contribution of APP variants to LOAD, with negative or conflicting results. We determined the variation in the 18 APP exons and flanking intronic sequences in a total of 350 LOAD patients from Spain. A total of 13 nucleotide changes were found and 6 were new and not found among 340 healthy controls, including the only missense change (D243N). The in silico analysis suggested that none of them would have an effect on pre-mRNA splicing or protein folding (D243N). Patients and controls were also genotyped for three APP promoter polymorphisms, and none of them was significantly associated with LOAD. We concluded that APP variants would not contribute to the risk of developing LOAD in our population.

A recent genome-wide association study (GWA) reported a significant association between single nucleotide polymorphisms (SNPs) at the PCDH11X gene and late-onset Alzheimer's disease (LOAD). Our research was designated to replicate this association, including non previously analyzed PCDH11X and PCDH11Y SNPs. We genotyped four PCDH11X and one PCDH11Y SNPs in a total of 420 LOAD patients and 350 healthy controls from Spain. Allele and genotype frequencies did not differ between patients and controls for the five SNPs, even after correcting by gender, age, and APOE-e4 status. Our data were in agreement with recent reports that failed to confirm the association between PCDH11X polymorphisms and LOAD, and extended the lack of association to common PCDH11Y variants.

MicroRNAs are small RNA sequences that negatively regulate gene expression by binding to the 3' untranslated regions of mRNAs. MiR-133b has been implicated in Parkinson's disease (PD) by a mechanism that involves the regulation of the transcription factor PITX3. The variation in these genes could contribute to the risk of developing PD. We searched for DNA variants in miR-133 and PITX3 genes in PD patients and healthy controls from Spain. We found common DNA variants in the three miR-133 genes. Genotyping of a first set of patients (n = 777) and controls (n = 650) showed a higher frequency of homozygous for a miR-133b variant (-90 del A) in PD-patients (6/575; 1%) than in healthy controls (0/650) (P = 0.03). However, this association was not confirmed in a second set of patients (1/250; 0.4%) and controls (2/210; 1%). No common PITX3 variants were associated with PD, although a rare missense change (G32S) was found in only one patient and none of the controls. In conclusion, we report the variation in genes of a pathway that has been involved in dopaminergic neuron differentiation and survival. Our work suggests that miR-133 and PITX3 gene variants did not contribute to the risk for PD.

Background Angiotensin and serotonin have been identified as inducers of cardiac hypertrophy. DNA polymorphisms at the genes encoding components of the angiotensin and serotonin systems have been associated with the risk of developing cardiovascular diseases, including left ventricular hypertrophy (LVH). Methods We genotyped five polymorphisms of the AGT, ACE, AT1R, 5-HT2A, and 5-HTT genes in 245 patients with Hypertrophic Cardiomyopathy (HCM; 205 without an identified sarcomeric gene mutation), in 145 patients with LVH secondary to hypertension, and 300 healthy controls. Results We found a significantly higher frequency of AT1R 1166 C carriers (CC+AC) among the HCM patients without sarcomeric mutations compared to controls (p = 0.015; OR = 1.56; 95%CI = 1.09-2.23). The AT1R 1166 C was also more frequent among patients who had at least one affected relative, compared to sporadic cases. This allele was also associated with higher left ventricular wall thickness in both, HCM patients with and without sarcomeric mutations. Conclusions The 1166 C AT1R allele could be a risk factor for cardiac hypertrophy in patients without sarcomeric mutations. Other variants at the AGT, ACE, 5-HT2A and 5-HTT did not contribute to the risk of cardiac hypertrophy.

Impaired mitochondrial function and an increased number of mutations in mitochondrial DNA (mtDNA) has been found in brains of patients with late-onset Alzheimer's disease (LOAD). The TFAM-gene encodes the mitochondrial transcription factor A, a protein that controls the transcription, replication, damage sensing, and repair of mtDNA. TFAM is on human chromosome region 10q21.1, where a locus for LOAD has been mapped. Our objective was to determine the role of TFAM-gene variation in the risk of LOAD. The seven TFAM coding exons were analysed through single strand conformation analysis and direct sequencing in a cohort of Spanish LOAD-patients and healthy controls. We found four common polymorphisms, two in the flanquing intronic and two in the coding sequences. Polymorphism rs1937 (+35 G/C) was the only missense change (S12T). Genotyping of this polymorphism in 300 LOAD-patients and 183 healthy controls showed a significantly higher frequency of GG-homozygotes in the patients (92% vs. 86%; p=0.04; OR=1.91, 95%CI=1.02-3.50). This suggests that S12 is a risk factor for LOAD in our population. In conclusion, rare variants (mutations) in the TFAM gene were not found in LOAD-patients, but the S12T polymorphism was a moderate risk factor for LOAD in our population.

Mitochondrial function is necessary to supply the energy required for cell metabolism. Mutations/polymorphisms in mitochondrial DNA (mtDNA) have been implicated in Parkinson's disease (PD). The mitochondrial transcription factor A (TFAM) controls the transcription of mtDNA and regulates the mtDNA-copy number, thus being important for maintaining ATP production. TFAM dysfunction may also be involved in PD, and TFAM gene mutations/polymorphisms could contribute to the risk of developing PD. We searched for gene variants in the seven TFAM-exons in a total of 250 PD-patients. We found five common polymorphisms, and only one was a missense change (S12T in exon 1). Genotype and allele frequencies did not differ between patients and healthy controls (n = 225) for the five polymorphisms. Our work suggests that TFAM-variants did not contribute to the risk of developing PD.

Polymorphisms at different genes have been proposed as determinants of the risk for developing late-onset Alzheimer's disease (LOAD). Among the several candidate genes are those that encode proteins involved in neuronal degeneration/survival. Studies of primary neuronal cultures supported that members of the myocyte enhancing factor-2 (MEF2) family of transcription factors have an anti-apoptotic effect, regulating the expression of proteins involved in neuronal survival and differentiation. We analysed the MEF2A gene in a total of 357 patients (mean age 72 years, range 60–97 years). Among others, a Pro279Leu in exon 8 and a polyglutamine (CAG) repeat polymorphisms in exon 12 were found. These variants were also genotyped in 495 healthy controls (>50 years old), and the frequencies were statistically compared. Eight patients were 279L (six P/L and two L/L), compared to only one control (2% vs. 0.2%; p = 0.004, OR = 11.32). There was a significantly higher frequency of 279L-carriers among APOEɛ4+ (7/154 = 4.5%), compared to ɛ4 - (1/203) ( p = 0.02). In conclusion, our work suggests that the variation at the MEF2A gene could be involved in the risk of developing LOAD. Because MEF2 has been related with neuronal survival, and the 279L allele has been related with a reduction in the transcriptional activation activity of MEF2A, the effect of this allele could be mediated through a down-regulation of antiapoptotic genes.

Mutations in mtDNA have been implicated in the development of hypertrophic cardiomyopathy (HCM), including cases from families with a maternal transmission. Alleles at several polymorphic sites in mtDNA define different haplogroups and some of these haplogroups have been involved in the risk of developing several diseases in which mitochondria should be involved. We analysed the association between the nine common European haplogroups and HCM. A total of 130 Spanish patients and 300 healthy controls were genotyped for eight mitochondrial single nucleotide polymorphisms (SNPs) through polymerase chain reaction followed by digestion with a restriction enzyme (PCR-RFLP). We compared the frequencies of these polymorphisms and mitochondrial haplogroups between patients and controls. Haplogroup T, specifically defined by 13368A, was significantly involved in the risk of developing HCM in our population ( p =0.007; OR=2.42; 95% CI=1.25–4.67). Our data suggest that the genetic variation at the mitochondrial genome could significantly contribute to the risk for HCM.