Copy number variation underlies complex phenotypes in domestic dog breeds and other canids.

Extreme phenotypic diversity, a history of artificial selection, and socioeconomic value make domestic dog breeds a compelling subject for genomic research. Copy number variation (CNV) is known to account for a significant part of inter-individual genomic diversity in other systems. However, a comprehensive genome-wide study of structural variation as it relates to breed-specific phenotypes is lacking.

Mapping co-ancestry connections between the genome of a Medieval individual and modern Europeans.

Historical genetic links among similar populations can be difficult to establish. Identity by descent (IBD) analyses find genomic blocks that represent direct genealogical relationships among individuals. However, this method has rarely been applied to ancient genomes because IBD stretches are progressively fragmented by recombination and thus not recognizable after few tens of generations.

Genome-wide association analyses of risk tolerance and risky behaviors in over 1 million individuals identify hundreds of loci and shared genetic influences.

Humans vary substantially in their willingness to take risks. In a combined sample of over 1 million individuals, we conducted genome-wide association studies (GWAS) of general risk tolerance, adventurousness, and risky behaviors in the driving, drinking, smoking, and sexual domains. Across all GWAS, we identified hundreds of associated loci, including 99 loci associated with general risk tolerance.

Combining Multiple Hypothesis Testing with Machine Learning Increases the Statistical Power of Genome-wide Association Studies.

The standard approach to the analysis of genome-wide association studies (GWAS) is based on testing each position in the genome individually for statistical significance of its association with the phenotype under investigation. To improve the analysis of GWAS, we propose a combination of machine learning and statistical testing that takes correlation structures within the set of SNPs under investigation in a mathematically well-controlled manner into account. The novel two-step algorithm, COMBI, first trains a support vector machine to determine a subset of candidate SNPs and then performs hypothesis tests for these SNPs together with an adequate threshold correction.

Pharmacogenomic study in patients with multiple sclerosis: Responders and nonresponders to IFN-β.

Objectives: We aimed to investigate the association between polymorphisms located in type I interferon (IFN)-induced genes, genes belonging to the toll-like receptor (TLR) pathway, and genes encoding neurotransmitter receptors and the response to IFN-β treatment in patients with multiple sclerosis (MS).

Methods: In a first or screening phase of the study, 384 polymorphisms were genotyped in 830 patients with MS classified into IFN-β responders (n = 416) and nonresponders (n = 414) according to clinical criteria. In a second or validation phase, the most significant polymorphisms associated with IFN-β response were genotyped in an independent validation cohort of 555 patients with MS (281 IFN-β responders and 274 nonresponders).

The genome sequencing of an albino Western lowland gorilla reveals inbreeding in the wild.

Background: The only known albino gorilla, named Snowflake, was a male wild born individual from Equatorial Guinea who lived at the Barcelona Zoo for almost 40 years. He was diagnosed with non-syndromic oculocutaneous albinism, i.e.

New subtype of spinocerebellar ataxia with altered vertical eye movements mapping to chromosome 1p32.

Importance: To provide clinical and genetic diagnoses for patients' conditions, it is important to identify and characterize the different subtypes of spinocerebellar ataxia (SCA).

Objective: To clinically and genetically characterize a Spanish kindred with pure SCA presenting with altered vertical eye movements. DESIGN Family study of ambulatory patients.

Select your SNPs (SYSNPs): a web tool for automatic and massive selection of SNPs.

Association studies are the choice approach in the discovery of the genomic basis of complex traits. To carry out such analysis, researchers frequently need to (1) select optimally informative sets of Single Nucleotide Polymorphisms (SNPs) in candidate regions and (2) annotate the results of associations found by means of genome-wide SNP arrays. These are complex tasks, since many criteria have to be considered, including the SNPs' functional properties, technological information and haplotype frequencies in given populations.

How to analyze many contingency tables simultaneously in genetic association studies.

We study exact tests for (2 x 2) and (2 x 3) contingency tables, in particular exact chi-squared tests and exact tests of Fisher type. In practice, these tests are typically carried out without randomization, leading to reproducible results but not exhausting the significance level. We discuss that this can lead to methodological and practical issues in a multiple testing framework when many tables are simultaneously under consideration as in genetic association studies.

Genome-wide association studies pipeline (GWASpi): a desktop application for genome-wide SNP analysis and management.

Motivation: Genome-wide association studies (GWAS) based on single nucleotide polymorphism (SNP) arrays are the most widely used approach to detect loci associated to human traits. Due to the complexity of the methods and software packages available, each with its particular format requiring intricate management workflows, the analysis of GWAS usually confronts scientists with steep learning curves. Indeed, the wide variety of tools makes the parsing and manipulation of data the most time consuming and error prone part of a study.

Recent human evolution has shaped geographical differences in susceptibility to disease.

Background: Searching for associations between genetic variants and complex diseases has been a very active area of research for over two decades. More than 51,000 potential associations have been studied and published, a figure that keeps increasing, especially with the recent explosion of array-based Genome-Wide Association Studies. Even if the number of true associations described so far is high, many of the putative risk variants detected so far have failed to be consistently replicated and are widely considered false positives.

Gender-associated differences of perforin polymorphisms in the susceptibility to multiple sclerosis.

The granule-dependent exocytosis pathway is an important mechanism to induce apoptosis by CD8(+) T cells and NK cells and involves lytic molecules such as perforin. In the current study, we investigated the perforin 1 gene (PRF1) as a candidate for multiple sclerosis (MS) susceptibility in the Spanish population. We genotyped three PRF1 single nucleotide polymorphisms (rs885822, rs10999426, and rs3758562) in 420 patients with MS and 512 controls.

Genome-wide scan of 500,000 single-nucleotide polymorphisms among responders and nonresponders to interferon beta therapy in multiple sclerosis.

Background: Interferon beta is 1 of 2 first-line treatments for relapsing-remitting multiple sclerosis (MS). However, not all patients respond to interferon beta therapy, and to date there is a lack of surrogate markers that reliably correlate with responsiveness to interferon beta therapy in MS.

Objective: To identify allelic variants that influence response to interferon beta therapy in patients with MS.

Decay of linkage disequilibrium within genes across HGDP-CEPH human samples: most population isolates do not show increased LD.

Background: It is well known that the pattern of linkage disequilibrium varies between human populations, with remarkable geographical stratification. Indirect association studies routinely exploit linkage disequilibrium around genes, particularly in isolated populations where it is assumed to be higher. Here, we explore both the amount and the decay of linkage disequilibrium with physical distance along 211 gene regions, most of them related to complex diseases, across 39 HGDP-CEPH population samples, focusing particularly on the populations defined as isolates.

The measurement of the lactonase activity of paraoxonase-1 in the clinical evaluation of patients with chronic liver impairment.

Aims: We investigated the analytical performance of a new assay of the lactonase activity of paraoxonase-1 and its efficacy in the assessment of liver damage.

Design And Methods: Serum lactonase activity was determined by the hydrolysis of 5-thiobutyl butyrolactone in 633 healthy individuals and 369 patients with chronic liver disease. Paraoxonase-1, 2, and 3 gene polymorphisms were analyzed by the MassArray method.

SNP analysis to results (SNPator): a web-based environment oriented to statistical genomics analyses upon SNP data.

Unlabelled: Single nucleotide polymorphisms (SNPs) are the most widely used marker in studies to assess associations between genetic variants and complex traits or diseases. They are also becoming increasingly important in the study of the evolution and history of humans and other species. The analysis and processing of SNPs obtained thanks to high-throughput technologies imply the time consuming and costly use of different, complex and usually format-incompatible software.