A CNGB1 Frameshift Mutation in Papillon and Phalene Dogs with Progressive Retinal Atrophy

Peer reviewe

Assessment of Canine \u3cem\u3eBEST1\u3c/em\u3e Variations Identifies New Mutations and Establishes an Independent Bestrophinopathy Model (\u3cem\u3ecmr3\u3c/em\u3e)

Purpose: Mutations in bestrophin 1 (BEST1) are associated with a group of retinal disorders known as bestrophinopathies in man and canine multifocal retinopathies (cmr) in the dog. To date, the dog is the only large animal model suitable for the complex characterization and in-depth studies of Best-related disorders. In the first report of cmr, the disease was described in a group of mastiff-related breeds (cmr1) and the Coton de Tulear (cmr2). Additional breeds, e.g., the Lapponian herder (LH) and others, subsequently were recognized with similar phenotypes, but linked loci are unknown. Analysis of the BEST1 gene aimed to identify mutations in these additional populations and extend our understanding of genotype–phenotype associations. Methods: Animals were subjected to routine eye exams, phenotypically characterized, and samples were collected for molecular studies. Known BEST1 mutations were assessed, and the canine BEST1 coding exons were amplified and sequenced in selected individuals that exhibited a cmr compatible phenotype but that did not carry known mutations. Resulting sequence changes were genotyped in several different breeds and evaluated in the context of the phenotype. Results: Seven novel coding variants were identified in exon 10 of cBEST1. Two linked mutations were associated with cmr exclusive to the LH breed (cmr3). Two individuals of Jämthund and Norfolk terrier breeds were heterozygous for two conservative changes, but these were unlikely to have disease-causing potential. Another three substitutions were found in the Bernese mountain dog that were predicted to have a deleterious effect on protein function. Previously reported mutations were excluded from segregation in these populations, but cmr1 was confirmed in another mastiff-related breed, the Italian cane corso. Conclusions: A third independent canine model for human bestrophinopathies has been established in the LH breed. While exhibiting a phenotype comparable to cmr1 and cmr2, the novel cmr3 mutation is predicted to be based on a distinctly different molecular mechanism. So far cmr2 and cmr3 are exclusive to a single dog breed each. In contrast, cmr1 is found in multiple related breeds. Additional sequence alterations identified in exon 10 of cBEST1 in other breeds exhibit potential disease-causing features. The inherent genetic and phenotypic variation observed with retinal disorders in canines is complicated further by cmr3 being one of four distinct genetic retinal traits found to segregate in LH. Thus, a combination of phenotypic, molecular, and population analysis is required to establish a strong phenotype–genotype association. These results indicate that cmr has a larger impact on the general dog population than was initially suspected. The complexity of these models further confirms the similarity to human bestrophinopathies. Moreover, analyses of multiple canine models will provide additional insight into the molecular basis underlying diseases caused by mutations in BEST1

Canine MPV17 truncation without clinical manifestations

Mitochondrial DNA depletion syndromes (MDS) are often serious autosomal recessively inherited disorders characterized by tissue-specific mtDNA copy number reduction. Many genes, including MPV17, are associated with the hepatocerebral form of MDS. MPV17 encodes for a mitochondrial inner membrane protein with a poorly characterized function. Several MPV17 mutations have been reported in association with a heterogeneous group of early-onset manifestations, including liver disease and neurological problems. Mpv17-deficient mice present renal and hearing defects. We describe here a MPV17 truncation mutation in dogs. We found a 1-bp insertion in exon 4 of the MPV17 gene, resulting in a frameshift and early truncation of the encoded protein. The mutation halves MPV17 expression in the lymphocytes of the homozygous dogs and the truncated protein is not translated in transfected cells. The insertion mutation is recurrent and exists in many unrelated breeds, although is highly enriched in the Boxer breed. Unexpectedly, despite the truncation of MPV17, we could not find any common phenotypes in the genetically affected dogs. The lack of observable phenotype could be due to a late onset, mild symptoms or potential tissue-specific compensatory mechanisms. This study suggests species-specific differences in the manifestation of the MPV17 defects and establishes a novel large animal model to further study MPV17 function and role in mitochondrial biology.Peer reviewe

A Novel Missense Mutation in ADAMTS10 in Norwegian Elkhound Primary Glaucoma

The PLOS ONE Staff (2015) Correction: A Novel Missense Mutation in ADAMTS10 in Norwegian Elkhound Primary Glaucoma. PLoS ONE 10(2): e0118256. doi:10.1371/journal.pone.0118256Peer reviewe

Genome-Wide Association Study Identifies a Novel Canine Glaucoma Locus

Peer reviewe

Common Inflammation-Related Candidate Gene Variants and Acute Kidney Injury in 2647 Critically Ill Finnish Patients

Acute kidney injury (AKI) is a syndrome with high incidence among the critically ill. Because the clinical variables and currently used biomarkers have failed to predict the individual susceptibility to AKI, candidate gene variants for the trait have been studied. Studies about genetic predisposition to AKI have been mainly underpowered and of moderate quality. We report the association study of 27 genetic variants in a cohort of Finnish critically ill patients, focusing on the replication of associations detected with variants in genes related to inflammation, cell survival, or circulation. In this prospective, observational Finnish Acute Kidney Injury (FINNAKI) study, 2647 patients without chronic kidney disease were genotyped. We defined AKI according to Kidney Disease: Improving Global Outcomes (KDIGO) criteria. We compared severe AKI (Stages 2 and 3, n = 625) to controls (Stage 0, n = 1582). For genotyping we used iPLEX(TM) Assay (Agena Bioscience). We performed the association analyses with PLINK software, using an additive genetic model in logistic regression. Despite the numerous, although contradictory, studies about association between polymorphisms rs1800629 in TNFA and rs1800896 in IL10 and AKI, we found no association (odds ratios 1.06 (95% CI 0.89-1.28, p = 0.51) and 0.92 (95% CI 0.80-1.05, p = 0.20), respectively). Adjusting for confounders did not change the results. To conclude, we could not confirm the associations reported in previous studies in a cohort of critically ill patients.Peer reviewe

Identification of Genomic Regions Associated with Phenotypic Variation between Dog Breeds using Selection Mapping

Peer reviewe

Pedigree of PRA affected Papillons and Phalènes.

<p>Pedigree indicates the affected dogs that were used in the study. Samples from six affected dogs were available for genotyping. Disease segregation is consistent with autosomal recessive mode of inheritance as all affected dogs are born from healthy parents and both sexes are affected. Obligate carrier parents of affected dogs are marked in the pedigree. Obligate carriers genotyped as heterozygous for <i>CNGB1</i> mutation are marked with a yellow background.</p

Genome wide association and linkage analyses.

<p><b>A</b>) A Manhattan plot of genome-wide case-control association analysis performed using 6 cases and 14 controls indicate the most highly associated region in CFA2. <b>B</b>) The PRA associated region on chromosome 2 spans from 61.4 Mb to 63.3 Mb based on association, linkage and joint analyses. <b>C</b>) Genotypes at the PRA associated region on CFA2. All cases share a 1.9 Mb homozygous block, and within this block SNPs BICF2S23238410, BICF2P309315 and BICF2P75954 show complete recessive segregation with the disease. <b>D</b>) Chromatograms of the c.2685delA (arrow), c.2687_2688insTAGCTA (shadowed) mutations in <i>CNGB1</i> gene in an affected (2) and normal (1) dog. The <i>CNGB1</i> gene is located between the two segregating SNPs (BICF2P309315, BICF2P75954).</p

CNGB1 protein alignments.

<p><b>A)</b> CNGB1 amino acid alignment of the normal and affected dogs. The p.Tyr889Serfs*5 mutation in the affected dog results in a loss of a significant part of the C-terminus of the protein and probable NMD of the <i>CNGB1</i> mRNA <b>B</b>) CNGB1 sequence alignment between different vertebrates. The mutation is located in a highly conserved region across species. The arrows mark the first mutated amino acid caused by the frameshift and the premature stop codon.</p