Rapid and accurate G M1-gangliosidosis diagnosis using a parentage testing microsatellite

The G M1-gangliosidosis is an autosomal recessive lysosomal storage disease caused by structural defects of the beta-galactosidase gene (GLB1) which lead to a severe phenotypical impairment in homozygous individuals, whereas heterozygous carriers remain clinically normal. Currently employed DNA parentage tests include the analysis of microsatellites, which also have a diagnostic predictive value. The aim of this study was to provide a reliable tool for genotyping the canine GLB1 which can be effectively integrated in parentage testing investigations. For this purpose the association between the GLB1 gene and the AHT K253 microsatellite was analyzed in 30 Alaskan huskies (11 GLB1+/+, 17 GLB1+/- and 2 GLB1-/- dogs). The 143 bp AHT K253 microsatellite allele was identified only in GLB1+/- and GLB1-/- animals and was in strong linkage disequilibrium with the causative mutation for G M1-gangliosidosis, a 19 bp duplication within exon 15 of the GLB1 gene. The results of the present study revealed a 100% concordance between the previous established genotypes and those obtained after the analysis of the AHT K253 microsatellite. Thus, the genotype of the AHT K253 microsatellite, which is routinely determined during dog parentage testing, has a high predictive value for the G M1-gangliosidosis carrier status.

Genetic analysis of white facial and leg markings in the Swiss Franches-Montagnes Horse Breed

White markings and spotting patterns in animal species are thought to be a result of the domestication process. They often serve for the identification of individuals but sometimes are accompanied by complex pathological syndromes. In the Swiss Franches-Montagnes horse population, white markings increased vastly in size and occurrence during the past 30 years, although the breeding goal demands a horse with as little depigmented areas as possible. In order to improve selection and avoid more excessive depigmentation on the population level, we estimated population parameters and breeding values for white head and anterior and posterior leg markings. Heritabilities and genetic correlations for the traits were high (h(2) > 0.5). A strong positive correlation was found between the chestnut allele at the melanocortin-1-receptor gene locus and the extent of white markings. Segregation analysis revealed that our data fit best to a model including a polygenic effect and a biallelic locus with a dominant-recessive mode of inheritance. The recessive allele was found to be the white trait-increasing allele. Multilocus linkage disequilibrium analysis allowed the mapping of the putative major locus to a chromosomal region on ECA3q harboring the KIT gene.

Hairless Streaks in Cattle Implicate TSR2 in Early Hair Follicle Formation

Four related cows showed hairless streaks on various parts of the body with no correlation to the pigmentation pattern. The stripes occurred in a consistent pattern resembling the lines of Blaschko. The non-syndromic hairlessness phenotype observed occurred across three generations of a single family and was compatible with an X-linked mode of inheritance. Linkage analysis and subsequent whole genome sequencing of one affected female identified two perfectly associated non-synonymous sequence variants in the critical interval on bovine chromosome X. Both variants occurred in complete linkage disequilibrium and were absent in more than 3900 controls. An ERCC6L missense mutation was predicted to cause an amino acid substitution of a non-conserved residue. Analysis in mice showed no specific Ercc6l expression pattern related to hair follicle development and therefore ERCC6L was not considered as causative gene. A point mutation at the 5'-splice junction of exon 5 of the TSR2, 20S rRNA accumulation, homolog (S. cerevisiae), gene led to the production of two mutant transcripts, both of which contain a frameshift and generate a premature stop codon predicted to truncate approximately 25% of the protein. Interestingly, in addition to the presence of both physiological TSR2 transcripts, the two mutant transcripts were predominantly detected in the hairless skin of the affected cows. Immunohistochemistry, using an antibody against the N-terminal part of the bovine protein demonstrated the specific expression of the TSR2 protein in the skin and the hair of the affected and the control cows as well as in bovine fetal skin and hair. The RNA hybridization in situ showed that Tsr2 was expressed in pre- and post-natal phases of hair follicle development in mice. Mammalian TSR2 proteins are highly conserved and are known to be broadly expressed, but their precise in vivo functions are poorly understood. Thus, by dissecting a naturally occurring mutation in a domestic animal species, we identified TSR2 as a regulator of hair follicle development.

A Multi-Breed Genome-Wide Association Analysis for Canine Hypothyroidism Identifies a Shared Major Risk Locus on CFA12.

Hypothyroidism is a complex clinical condition found in both humans and dogs, thought to be caused by a combination of genetic and environmental factors. In this study we present a multi-breed analysis of predisposing genetic risk factors for hypothyroidism in dogs using three high-risk breeds-the Gordon Setter, Hovawart and the Rhodesian Ridgeback. Using a genome-wide association approach and meta-analysis, we identified a major hypothyroidism risk locus shared by these breeds on chromosome 12 (p = 2.1x10-11). Further characterisation of the candidate region revealed a shared ~167 kb risk haplotype (4,915,018-5,081,823 bp), tagged by two SNPs in almost complete linkage disequilibrium. This breed-shared risk haplotype includes three genes (LHFPL5, SRPK1 and SLC26A8) and does not extend to the dog leukocyte antigen (DLA) class II gene cluster located in the vicinity. These three genes have not been identified as candidate genes for hypothyroid disease previously, but have functions that could potentially contribute to the development of the disease. Our results implicate the potential involvement of novel genes and pathways for the development of canine hypothyroidism, raising new possibilities for screening, breeding programmes and treatments in dogs. This study may also contribute to our understanding of the genetic etiology of human hypothyroid disease, which is one of the most common endocrine disorders in humans.

Outcomes in patients waiting for antiretroviral treatment in the Free State Province, South Africa: prospective linkage study

Objective: In South Africa, many HIV-infected patients experience delays in accessing antiretroviral therapy (ART). We examined pretreatment mortality and access to treatment in patients waiting for ART. Design: Cohort of HIV-infected patients assessed for ART eligibility at 36 facilities participating in the Comprehensive HIV and AIDS Management (CHAM) program in the Free State Province. Methods: Proportion of patients initiating ART, pre-ART mortality and risk factors associated with these outcomes were estimated using competing risks survival analysis. Results: Forty-four thousand, eight hundred and forty-four patients enrolled in CHAM between May 2004 and December 2007, of whom 22 083 (49.2%) were eligible for ART; pre-ART mortality was 53.2 per 100 person-years [95% confidence interval (CI) 51.8–54.7]. Median CD4 cell count at eligibility increased from 87 cells/ml in 2004 to 101 cells/ml in 2007. Two years after eligibility an estimated 67.7% (67.1–68.4%) of patients had started ART, and 26.2% (25.6–26.9%) died before starting ART. Among patients with CD4 cell counts below 25 cells/ml at eligibility, 48% died before ART and 51% initiated ART. Men were less likely to start treatment and more likely to die than women. Patients in rural clinics or clinics with low staffing levels had lower rates of starting treatment and higher mortality compared with patients in urban/peri-urban clinics, or better staffed clinics. Conclusions: Mortality is high in eligible patients waiting for ART in the Free State Province. The most immunocompromised patients had the lowest probability of starting ART and the highest risk of pre-ART death. Prioritization of these patients should reduce waiting times and pre-ART mortality.

(234)U/(238)U activity ratio disequilibrium technique for studying uranium mobility in the Opalinus Clay at Mont Terri, Switzerland

Mobility of naturally occurring U-238 and U-234 radionuclides was studied in a low permeability, reducing claystone formation (Opalinus Clay) near its contact with an overlying oxidising aquifer (Dogger Limestones) at Mont Terri, Switzerland. Our data point to a limited redistribution of U in some of the studied samples. Observed centimetre-scale U mobility is explained by slow diffusive transport of U-234 in the pore waters of the Opalinus Clay driven by spatially variable in situ supply (by alpha-recoil) of U-234 from the rock matrix. Metre-scale mobility is interpreted as a result of infiltration of meteoric water into the overlying aquifer which developed gradients of U concentration across the two rock formations. This triggered a slow in-diffusion of U with (U-234/U-238) > 1 into the Opalinus Clay as attested by a clear-cut pattern of decreasing bulk rock (U-234/U-238) inwards the Opalinus Clay, away from the Dogger Limestones.

Trauma registry record linkage: methodological approach to benefit from complementary data using the example of the German Pelvic Injury Register and the TraumaRegister DGU(®)

In Germany, hospitals can deliver data from patients with pelvic fractures selectively or twofold to two different trauma registries, i.e. the German Pelvic Injury Register (PIR) and the TraumaRegister DGU(®) (TR). Both registers are anonymous and differ in composition and content. We describe the methodological approach of linking these registries and reidentifying twofold documented patients. The aim of the approach is to create an intersection set that benefit from complementary data of each registry, respectively. Furthermore, the concordance of data entry of some clinical variables entered in both registries was evaluated.

Single linkage group per chromosome genetic linkage map for the horse, based on two three-generation, full-sibling, crossbred horse reference families

A genetic linkage map of the horse consisting of 742 markers, which comprises a single linkage group for each of the autosomes and the X chromosome, is presented. The map has been generated from two three-generation full-sibling reference families, sired by the same stallion, in which there are 61 individuals in the F2 generation. Each linkage group has been assigned to a chromosome and oriented with reference to markers mapped by fluorescence in situ hybridization. The average interval between markers is 3.7 cM and the linkage groups collectively span 2772 cM. The 742 markers comprise 734 microsatellite and 8 gene-based markers. The utility of the microsatellite markers for comparative mapping has been significantly enhanced by comparing their flanking sequences with the human genome sequence; this enabled conserved segments between human and horse to be identified. The new map provides a valuable resource for genetically mapping traits of interest in the horse.

Linkage mapping of ovine microphthalmia to chromosome 23, the sheep orthologue of human chromosome 18

PURPOSE: To characterize the phenotype and map the locus responsible for autosomal recessive inherited ovine microphthalmia (OMO) in sheep. METHODS: Microphthalmia-affected lambs and their available relatives were collected in a field, and experimental matings were performed to obtain affected and normal lambs for detailed necropsy and histologic examinations. The matings resulted in 18 sheep families with 48 cases of microphthalmia. A comparative candidate gene approach was used to map the disease locus within the sheep genome. Initially, 27 loci responsible for the microphthalmia-anophthalmia phenotypes in humans or mice were selected to test for comparative linkage. Fifty flanking markers that were predicted from comparative genomic analysis to be closely linked to these genes were tested for linkage to the disease locus. After observation of statistical evidence for linkage, a confirmatory fine mapping strategy was applied by further genotyping of 43 microsatellites. RESULTS: The clinical and pathologic examinations showed slightly variable expressivity of isolated bilateral microphthalmia. The anterior eye chamber was small or absent, and a white mass admixed with cystic spaces extended from the papilla to the anterior eye chamber, while no recognizable vitreous body or lens was found within the affected eyes. Significant linkage to a single candidate region was identified at sheep chromosome 23. Fine mapping and haplotype analysis assigned the candidate region to a critical interval of 12.4 cM. This ovine chromosome segment encompasses an ancestral chromosomal breakpoint corresponding to two orthologue segments of human chromosomes 18, short and long arms. For the examined animals, we excluded the complete coding region and adjacent intronic regions of ovine TGIF1 to harbor disease-causing mutations. CONCLUSIONS: This is the first genetic localization for hereditary ovine isolated microphthalmia. It seems unlikely that a mutation in the TGIF1 gene is responsible for this disorder. The studied sheep represent a valuable large animal model for similar human ocular phenotypes.