Life in a vacuum

Activating mutations in the Transient Receptor Potential channel C6 (TRPC6) cause autosomal dominant focal segmental glomerular sclerosis (FSGS). TRPC6 expression is upregulated in renal biopsies of patients with idiopathic membranous glomerulopathy (iMN) and animal models thereof. In iMN, disease progression is characterized by glomerulosclerosis. In addition, a context-dependent TRPC6 overexpression was recently suggested in complement-mediated podocyte injury in e.g. iMN. Hence, we hypothesized that genetic variants in TRPC6 might affect susceptibility to development or progression of iMN.Genomic DNA was isolated from blood samples of 101 iMN patients and 292 controls. By direct sequencing of the entire TRPC6 gene, 13 single nucleotide polymorphisms (SNPs) were identified in the iMN cohort, two of which were causing an amino acid substitution (rs3802829; Pro15Ser and rs36111323, Ala404Val). No statistically significant differences in genotypes or allele frequencies between patients and controls were observed. Clinical outcome in patients was determined (remission n = 26, renal failure n = 46, persistent proteinuria n = 29, follow-up median 80 months {range 51-166}). The 13 identified SNPs showed no association with remission or renal failure. There were no differences in genotypes or allele frequencies between patients in remission and progressors.Our data suggest that TRPC6 polymorphisms do not affect susceptibility to iMN, or clinical outcome in iMN

Genotypes in iMN patients with clinical remission versus patients with renal failure.

<p>*N = 45 for renal failure.</p><p>*P-value for minor allele frequencies-comparison (Mann-Whitney U).</p

Primers used to sequence the 13 exons of <i>TRPC6</i>.

<p>F, forward; R, reverse.</p

<i>TRPC6</i> variants in patients with iMN (n = 101).

<p>Chr  =  chromosome; position  =  basepair position based on UCSC genome browser version Human Feb. 2009 (GRCh37/hg19) assembly; name  =  rs identifier; ref  =  genomic reference allele; all  =  alleles; CEU AF  =  allele frequencies variant allele in control population. Control population consists of Caucasian population from 1000 Genomes project (release 10 - March 2012), complemented with data form 292 geographically matched controls for variants marked with **; ∧ =  not reported in 1000 Genomes project; AF patient  =  patient minor allele frequencies; p-value  =  comparison allele frequencies controls and patients; AF PLA2R  =  minor allele frequencies in PLA2R positive patients (n = 62); p-value*  =  comparison allele frequencies controls and PLA2R positive patients; genomic level  =  NC_000002.11; ref cDNA  =  reference allele cDNA (given that TRPC6 is on the negative strand); cDNA  =  NM_004621.5; prot. level  =  NP_004612.2; CCD  =  coiled-coiled domain; TMD  =  transmembrane domain.</p

TRPC6 topology.

<p>Structure of the TRPC6 monomer. TRPC6 belongs to the large family of TRP channels, which contain six transmembrane domains, one pore-forming region and large intracellular N- and C-tails. Four subunits are required to assemble a functional channel. In the pococyte, TRPC6 is part of the slit diaphragm multiprotein complex. TRP: transient receptor potential, ANK: Ankyrin repeat, cc: coiled–coiled domain, CIRB: CaM/IP3R-binding domain.</p

Dutch myotonic dystrophy type 2 patients and a North-African DM2 family carry the common European founder haplotype

Myotonic dystrophy type 2 (DM2) is a progressive multisystem disease with muscle weakness and myotonia as main characteristics. The disease is caused by a repeat expansion in the zinc-finger protein 9 (ZNF9) gene on chromosome 3q21. Several reports show that patients from European ancestry share an identical haplotype surrounding the ZNF9 gene. In this study, we investigated whether the Dutch DM2 population carries the same founder haplotype. In all, 40 Dutch DM2 patients from 16 families were genotyped for eight short tandem repeat markers surrounding the ZNF9 gene. In addition, the single-nucleotide polymorphism (SNP) rs1871922 located in the first intron of DM2 was genotyped. Results were compared with previously published haplotypes from unrelated Caucasian patients. The repeat lengths identified in this study were in agreement with existing literature. In 36 patients of our population, we identified three common haplotypes. One patient showed overlap with the common haplotype for only one marker closest to the ZNF9 gene. The haplotype from a family originating from Morocco showed overlap with that of the patients of European descent for a region of 222 kb. All patients carried at least one C allele of SNP rs1871922 indicating that all patients carry the European founder haplotype. We conclude that DM2 patients from the Netherlands, including a North-African family, harbor a common haplotype surrounding the ZNF9 gene. This data show that the Dutch patients carry the common founder haplotype and strongly suggest that DM2 mutations in Europe and North Africa originate from a single ancestral founder

Genetic variants in toll-like receptors are not associated with rheumatoid arthritis susceptibility or anti-tumour necrosis factor treatment outcome

Contains fulltext : 88531.pdf (publisher's version ) (Open Access)BACKGROUND: Several studies point to a role of Toll-like receptors (TLRs) in the development of rheumatoid arthritis (RA). We investigated if genetic variants in TLR genes are associated with RA and response to tumour necrosis factor blocking (anti-TNF) medication. METHODOLOGY AND PRINCIPAL FINDINGS: 22 single nucleotide polymorphisms (SNPs) in seven TLR genes were genotyped in a Dutch cohort consisting of 378 RA patients and 294 controls. Significantly associated variants were investigated in replication cohorts from The Netherlands, United Kingdom and Sweden (2877 RA patients and 2025 controls). 182 of the Dutch patients were treated with anti-TNF medication. Using these patients and a replication cohort (269 Swedish patients) we analysed if genetic variants in TLR genes were associated with anti-TNF outcome. In the discovery phase of the study we found a significant association of SNPs rs2072493 in TLR5 and rs3853839 in TLR7 with RA disease susceptibility. Meta-analysis of discovery and replication cohorts did not confirm these findings. SNP rs2072493 in TLR5 was associated with anti-TNF outcome in the Dutch but not in the Swedish population. CONCLUSION: We conclude that genetic variants in TLRs do not play a major role in susceptibility for developing RA nor in anti-TNF treatment outcome in a Caucasian population