Juan Gómez

Mutations in filamin C cause a new form of familial hypertrophic cardiomyopathy

Mutations in different genes encoding sarcomeric proteins are responsible for 50-60% of familial cases of hypertrophic cardiomyopathy (HCM); however, the genetic alterations causing the disease in one-third of patients are currently unknown. Here we describe a case with familial HCM of unknown cause. Whole-exome sequencing reveals a variant in the gene encoding the sarcomeric protein filamin C (p.A1539T) that segregates with the disease in this family. Sequencing of 92 HCM cases identifies seven additional variants segregating with the disease in eight families. Patients with FLNC mutations show marked sarcomeric abnormalities in cardiac muscle, and functional analysis reveals that expression of these FLNC variants resulted in the formation of large filamin C aggregates. Clinical studies indicate that FLNC-mutated patients have higher incidence of sudden cardiac death. On the basis of these findings, we conclude that mutations in the gene encoding the sarcomeric protein filamin C cause a new form of familial HMC.

Late-onset Alzheimer's disease is associated with mitochondrial DNA 7028C/haplogroup H and D310 poly-C tract heteroplasmy

There is growing evidence that mitochondria play an important role in the pathogenesis of late-onset Alzheimers disease (LOAD) [1]. Certain haplogroups defined by combinations of common mitochondrial DNA (mtDNA) single-nucleotide polymorphisms (SNPs) have been associated with longevity and age-related diseases. Recent studies reported a significant association between haplogroup H and LOAD [2–4] (supplementary Table 1). Differences between the mtDNA SNPs/haplogroups in the efficiency of oxygen consumption and ATP and ROS production could partly explain these associations [5]. Although the relative risk attributed to this haplogroup was low (<1.5) in all the studies, this could have important implications considering the high incidence of LOAD at the population level. It is therefore very important to determine the influence of mtDNA polymorphisms in LOAD by studying large cohorts from different populations. We report the results from Asturias (northern Spain) based on a total of 500 LOAD patients and 500 controls (Supplementary file). The mtDNA 7028C was significantly more frequent among the patients (p=0.001; OR=1.52, 95% CI=1.18– 1.95; Table 1). Allele frequencies for the other six SNPs that defined the mitochondrial haplogroups did not differ between patients and controls (data not shown). Haplogroup H (defined by 7028C) was significantly more frequent among the patients (Supplementary file). Multiple logistic regression with apolipoprotein E gene (APOE)-ε4 and mtDNA 7028C status, age, and gender as covariates showed that APOE-ε4 and 7028C were associated with LOAD. We found a synergistic effect between the two risk variants: the OR for APOE-ε4 + 7028C (OR=5.30, 95% CI=3.72–7.54) was higher than the OR for each separately. The non-APOE-ε4 + 7028T had a protective effect (OR= 0.43; 95%CI=0.33–0.75). Patients and controls were classified as D310 7C or D310 >7C (poly-C tract at position 310 of the mtDNA, Supplementary file). We found a significantly higher frequency of the >7C alleles among the patients (Table 1). Electronic supplementary material The online version of this article (doi:10.1007/s10048-011-0295-4) contains supplementary material, which is available to authorized users. E. Coto (*) : J. Gómez :B. Alonso :A. I. Corao :M. Díaz : V. Álvarez Genética Molecular-Laboratorio de Medicina, Hospital Universitario Central Asturias, 33006 Oviedo, Spain e-mail: eliecer.coto@sespa.princast.es

Microtubule organization is determined by the shape of epithelial cells

Interphase microtubule organization is critical for cell function and tissue architecture. In general, physical mechanisms are sufficient to drive microtubule organization in single cells, whereas cells within tissues are thought to utilize signalling mechanisms. By improving the imaging and quantitation of microtubule alignment within developing Drosophila embryos, here we demonstrate that microtubule alignment underneath the apical surface of epithelial cells follows cell shape. During development, epidermal cell elongation and microtubule alignment occur simultaneously, but by perturbing cell shape, we discover that microtubule organization responds to cell shape, rather than the converse. A simple set of microtubule behaviour rules is sufficient for a computer model to mimic the observed responses to changes in cell surface geometry. Moreover, we show that microtubules colliding with cell boundaries zip-up or depolymerize in an angle-dependent manner, as predicted by the model. Finally, we show microtubule alignment responds to cell shape in diverse epithelia.

Non Optical Semi-Conductor Next Generation Sequencing of the Main Cardiac QT-Interval Duration Genes in Pooled DNA Samples

DNA variants at the genes encoding cardiac channels have been associated with inherited arrhythmias and the QT interval in the general population. Next generation sequencing technologies would be of special interest to uncover the genetic variation at these genes. The amplification and sequencing of DNA pools (instead of single individuals) would facilitate the rapid and cost-effective screening of large amounts of individuals. However, this pooling strategy could result in a signal of the rare variants below the detection capacity. To validate this approach, a pool of 20 individuals with known rare unique variants in five genes was amplified in only two tubes and sequenced using the non optical semi-conductor (Ion Torrent PGM, Life Technologies) technology. We show that this could be an effective strategy for the screening of large cohorts. Among others, this would facilitate the discovery of new sequence variants linked to cardiac arrhythmia in the general population.

Mitochondrial DNA haplogroups and risk of new-onset diabetes among tacrolimus-treated renal transplanted patients.

BACKGROUND AND AIMS Tacrolimus (Tac) is an immunosuppressive drug widely used to avoid organ rejection. New-onset diabetes after transplantation (NODAT) is a major complication among transplanted patients who receive Tac. The increased risk for NODAT could be partly mediated by the effect of Tac on mitochondria from pancreatic beta-cells. Common and rare mitochondrial DNA variants have been linked to the risk of diabetes. Our aim was to determine whether mtDNA polymorphisms/haplogroups were associated with NODAT in Tac-treated kidney transplanted. METHODS Seven polymorphisms that define the common European haplogroups were determined in 115 NODAT and 197 no-NODAT patients. RESULTS Haplogroup H was significantly more frequent in the NODAT group (50% vs. 35%; p=0.01, OR=1.82). There was no difference between patients without and with (n=106) D2M prior to the transplant. CONCLUSIONS Mitochondrial haplogroup H was associated with the risk for NODAT among Tac-treated transplanted patients. The reported differences between the mtDNA variants could explain the increased NODAT-risk among H-patients.

The Cw6 and late-cornified envelope genotype plays a significant role in anti-tumor necrosis factor response among psoriatic patients.

Our aim was to determine whether the HLA-Cw6 and late-cornified envelope (LCE) deletion polymorphisms were related to disease improvement among psoriasis patients treated with anti-tumor necrosis factor (TNF) antibodies. The study included a total of 116 patients. Positive response (68%) was defined as a reduction of at least 75% of the Psoriasis Area and Severity Index (PASI) after 24 weeks of starting the anti-TNF therapy. We found a trend toward a better response among Cw6-positive patients. The frequency of patients who did not reach the PASI75 was higher among the LCE-DD patients (P=0.028; odds ratio=2.45, 95% confidence interval=1.09-5.52). Patients who were Cw6-positive and LCE-I carriers (ID/II) were significantly more likely to reach PASI75 than those who were Cw6-negative and LCE-DD (P=0.034; odds ratio=3.14, 95% confidence interval=1.07-9.24). In conclusion, we found an interaction between the HLA-Cw6 and LCE genotypes on disease improvement among psoriatic patients treated with anti-TNFs.

Association between a MYH9 polymorphism (rs3752462) and renal function in the Spanish RENASTUR cohort.

The MYH9 gene encodes a protein that is expressed in the kidney glomerular podocytes. MYH9 single nucleotide polymorphisms (SNPs) have been linked to the risk for chronic kidney disease (CKD) and end stage renal disease. Our aim was to determine whether MYH9 SNPs were associated with renal disease in Spanish Caucasians. The RENASTUR cohort consisted of 592 Spanish Caucasians, aged 55-85 years. They were genotyped for SNPs rs3752462 and rs4821480, which tagged haplotype E. The main values between individuals with a glomerular filtration rate (eGFR) <60 and ≥ 60 ml/min/1.73 m(2) were statistically compared. The next variables were significantly associated with the eGFR in the univariate analysis: age, gender, type 2 diabetes, total cholesterol, total LDL-cholesterol, and the MYH9 rs3752462 (TC+TT genotypes; p=0.003). This SNP remained significantly associated with the eGFR in the multivariate analysis. In conclusion, SNP rs3752462 was an independent predictor of reduced eGFR in the Spanish RENASTUR population. The genotyping of this MYH9 SNP could help to identify individuals at risk of developing CKD.

Effect of the FTO rs9930506 Polymorphism on the Main Comorbidities of the Cardiorenal Metabolic Syndrome in an Elderly Spanish Cohort

Background/Aim: Fat mass and obesity-associated (FTO) gene polymorphisms have been linked to the risk of obesity and diabetes, two well-recognized risk factors for renal disease. Our aim was to determine whether a common FTO polymorphism was associated with a reduced estimated glomerular filtration rate (eGFR) independently of body mass index (BMI) and type 2 diabetes mellitus (T2DM) in a cohort of elderly individuals from the region of Asturias (Northern Spain; RENASTUR cohort). Methods: A total of 544 Spanish Caucasians aged 55-85 years were genotyped for the FTO rs9930506 single-nucleotide polymorphism (SNP). Individuals with a previous diagnosis of renal disease were not eligible for the study. The eGFR was calculated with the Modification of Diet in Renal Disease formula, and individuals with an eGFR of <60 ml/min/1.73 m2 (n = 91) were considered as having impaired renal function. The effect of alleles and genotypes on BMI, hypertension, diabetes, eGFR and blood lipid values was statistically determined. Results: The rs9930506 GG genotype was significantly more common in the group with a BMI of >25 (p = 0.03; odds ratio = 2.43; 95% CI: 1.09-5.43). Age and T2DM were significant risk factors for a reduced eGFR, but neither obesity nor the FTO genotypes were associated with a reduced eGFR. Conclusion: The common FTO rs9930506 polymorphism was a risk factor for overweight and obesity in the RENASTUR cohort. However, this SNP was not associated with other comorbidities of the cardiorenal metabolic syndrome in this population.

Resequencing of the IL12B gene in psoriasis patients with the rs6887695/rs3212227 risk genotypes

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.

KCNQ1 gene variants in the risk for type 2 diabetes and impaired renal function in the Spanish Renastur cohort

Several common KCNQ1 gene polymorphisms have been associated with the risk of type 2 diabetes (T2DM) and diabetic nephropathy. This effect is explained by the role of the kcnq1 protein as a potassium channel that in the pancreatic beta-cells drives an electrical signal that facilitates glucose-stimulated insulin secretion. The KCNQ1 gene is also expressed in the kidney, and could thus be implicated in the risk of developing impaired renal function. To test this hypothesis, we genotyped six common KCNQ1 gene variants (three single nucleotide polymorphisms, rs2237892, rs2237895, and rs231362, and three intronic indels) in 681 healthy elderly individuals (>65 years old) from the Spanish Renastur cohort. None of the six variants was associated with T2DM (180 diabetics vs. 581 non-diabetics). The intron 12 insertion allele was associated with a reduced estimated glomerular filtration rate (eGFR<60, n = 90 vs. eGFR≥60, n = 591; II vs ID + DD genotypes, p = 0.031, OR = 2.06, 95%CI = 1.12-4.14). We also performed a next generation sequencing search of variants in the coding regions of the KCNQ1 gene in 100 individuals with the extreme eGFR values. We found two rare amino acid changes (p.K393N and p.P408A) and the 393 Asn variant was found only among diabetics (n = 4; p = 0.05). The two rare alleles were present in the two eGFR groups. Our results suggest that a common KCNQ1 intron 12 indel polymorphism is a risk factor for impaired renal function independent of T2DM. If this association is confirmed by others, further research to determine the mechanism that drives this association would be warranted.