Classical Xanthinuria in Nine Israeli Families and Two Isolated Cases from Germany: Molecular, Biochemical and Population Genetics Aspects.

Classical xanthinuria is a rare autosomal recessive metabolic disorder caused by variants in the XDH (type I) or MOCOS (type II) genes. Thirteen Israeli kindred (five Jewish and eight Arab) and two isolated cases from Germany were studied between the years 1997 and 2013. Four and a branch of a fifth of these families were previously described. Here, we reported the demographic, clinical, molecular and biochemical characterizations of the remaining cases. Seven out of 20 affected individuals (35%) presented with xanthinuria-related symptoms of varied severity. Among the 10 distinct variants identified, six were novel: c.449G>T (p.(Cys150Phe)), c.1434G>A (p.(Trp478*)), c.1871C>G (p.(Ser624*)) and c.913del (p.(Leu305fs*1)) in the XDH gene and c.1046C>T (p.(Thr349Ileu)) and c.1771C>T (p.(Pro591Ser)) in the MOCOS gene. Heterologous protein expression studies revealed that the p.Cys150Phe variant within the Fe/S-I cluster-binding site impairs XDH biogenesis, the p.Thr349Ileu variant in the NifS-like domain of MOCOS affects protein stability and cysteine desulfurase activity, while the p.Pro591Ser and a previously described p.Arg776Cys variant in the C-terminal domain affect Molybdenum cofactor binding. Based on the results of haplotype analyses and historical genealogy findings, the potential dispersion of the identified variants is discussed. As far as we are aware, this is the largest cohort of xanthinuria cases described so far, substantially expanding the repertoire of pathogenic variants, characterizing structurally and functionally essential amino acid residues in the XDH and MOCOS proteins and addressing the population genetic aspects of classical xanthinuria.

An ancestral variant causing type I xanthinuria in Turkmen and Arab families is predicted to prevail in the Afro-Asian stone-forming belt.

Classical xanthinuria is a rare autosomal recessive metabolic disorder characterized by lack of xanthine dehydrogenase activity that often manifests as xanthine urolithiasis and risk of drug toxicity. Variants in the XDH or HMCS gene underlie classical xanthinuria type I and type II, respectively. Here we present two Israeli Arab families affected by type I xanthinuria in whom a c.2164A>T (Lys722Ter) variant in the XDH gene, previously reported in a Turkish family of Turkmen origin, was identified. Analysis of polymorphic markers surrounding the variant site revealed common haplotypes spanning 0.6 Mbp shared by all three, and 1.7 Mbp shared by two of the studied families. By applying Bayesian methods to a simple model of crossover events through generations in the chromosomes carrying the variant, the most recent common ancestor of these families was found to be 179 (95% credible limit 70) generations old. The estimated antiquity of the variant, the historical genealogy of the affected families and the history and present day dispersion of their people strongly suggest prevalence of this variant in the Afro-Asian stone-forming belt. As far as we are aware, this is a first report of an ancient variant causing xanthinuria with potential wide geographical dispersion.

The Price of Stress: High Bedtime Salivary Cortisol Levels Are Associated with Brain Atrophy and Cognitive Decline in Stroke Survivors. Results from the TABASCO Prospective Cohort Study.

BACKGROUND AND OBJECTIVE: Previous studies suggest that excessive cortisol levels after stroke are associated with cognitive dysfunction. However, limited data exist regarding associations between post-stroke cortisol levels, brain abnormalities, genetic factors, and cognitive outcome. We sought to study these issues in a longitudinal stroke survivors cohort. METHODS: Data from 182 cognitively intact ischemic stroke patients from the TABASCO study were available. Saliva cortisol levels (bedtime and post-awakening) and cognitive assessments were obtained on admission, and 6, 12, and 24 months thereafter. During hospitalization, patients underwent 3T MRI scans and APOE genotyping. RESULTS: Higher bedtime cortisol levels immediately post-stroke were associated with larger neurological deficits (p < 0.001), brain atrophy (p = 0.025), worse white matter integrity (p = 0.003), and worse cognitive results up to 24 months post-stroke. These findings remained significant when adjusted for age, gender, education, smoking, stroke severity, apolipoprotein E4 (ApoE4) status, and body mass index. ApoE4 negatively modified the relation between cortisol and memory. As a group, participants who presented with high admission bedtime cortisol levels continued to present relatively elevated bedtime levels across all examined time-points, and this group had inferior memory and executive functioning scores compared to the lower cortisol group 24 months post-stroke (p = 0.05, p = 0.035, respectively). Post-awakening cortisol levels were not associated with neuroimaging findings or cognitive scores. CONCLUSIONS: High bedtime salivary cortisol levels post-stroke may provide information about dysregulation of diurnal HPA-axis activity under acute challenge conditions, and predict worse cognitive outcome. ApoE4 genotype might modify this association. These findings call for specific stress management interventions in stroke survivors.

Predictors for poststroke outcomes: the Tel Aviv Brain Acute Stroke Cohort (TABASCO) study protocol.

BACKGROUND: Recent studies have demonstrated that even survivors of mild stroke experience residual damage, which persists and in fact increases in subsequent years. About 45% of stroke victims remain with different levels of disability. Identifying factors associated with poststroke cognitive and neurological decline could potentially yield more effective therapeutic opportunities. AIMS AND HYPOTHESIS: We hypothesize that data based on biochemical, neuroimaging, genetic and psychological measures can, in aggregate, serve as better predictors for subsequent disability, cognitive and neurological deterioration, and suggest possible interventions. DESIGN: The Tel-Aviv Brain Acute Stroke Cohort (TABASCO) study is an ongoing, prospective cohort study that will recruit approximately 1125 consecutive first-ever mild-moderate stroke patients. It is designed to evaluate the association between predefined demographic, psychological, inflammatory, biochemical, neuroimaging and genetic markers, measured during the acute phase, and long-term outcome: subsequent cognitive deterioration, vascular events (including recurrent strokes), falls, affect changes, functional everyday difficulties and mortality. DISCUSSION: This study is an attempt to comprehensively investigate the long-term outcome of mild-moderate strokes. Its prospective design will provide quantitative data on stroke recurrence, the incidence of other vascular events and the evaluation of cognitive, affective and functional decline. Identifying the factors associated with poststroke cognitive and functional decline could potentially yield more effective therapeutic approaches.

Association of the -757T>C polymorphism in the CRP gene with circulating C-reactive protein levels and carotid atherosclerosis.

INTRODUCTION: C-reactive protein (CRP) is an inflammatory protein that may play a role in the pathogenesis of atherosclerosis. CRP gene single nucleotide polymorphisms (SNPs) have been shown to be associated with CRP concentration; however, their independent effect on atherosclerosis has not been yet established. We aimed to determine whether the 5'-flanking -757T>C CRP gene polymorphism is associated with CRP concentration and carotid atherosclerosis. METHODS: We genotyped the -757T>C CRP gene SNP and determined the concentration of serum CRP, the intima-media thickness (IMT) of the common carotid artery and the existence of plaque/s in 612 apparently healthy men and women aged 66+/-10 years. RESULTS: Carriers of the CRP -757C allele presented with higher IMT and higher CRP concentrations (p=0.002, p=0.042, respectively). After adjustment for vascular risk factors, linear regression analysis showed an independent effect of CRP -757C allele on carotid IMT, beyond serum CRP concentrations. This SNP was also associated with carotid plaque occurrence (O.R. 1.74, 95% CI 1.1-2.77, p=0.002). CONCLUSIONS: The present study provides evidence that a genetic variant of CRP gene is associated with carotid atherosclerosis, independently of traditional vascular risk factors. Further large-scale genomic studies are required, which may identify the genetic vulnerable subjects to develop atherosclerosis.

Gender differences in the expression of erythrocyte aggregation in relation to B beta-fibrinogen gene polymorphisms in apparently healthy individuals.

An increased erythrocyte aggregation (EA) is associated with capillary slow flow, tissue hypoxemia and endothelial dysfunction. Fibrinogen is a major determinant in the formation of aggregated red blood cells. It has been suggested that the B beta-fibrinogen -455 G/A polymorphism is associated with erythrocyte hyperaggregability in men with coronary artery disease. The purpose of this study was to investigate the influence of the beta-fibrinogen -455 G/A polymorphism on erythrocyte aggregation in apparently healthy individuals. Plasma fibrinogen, red blood cell count, serum lipids, erythrocyte sedimentation rate, and the genotype of the B beta-fibrinogen -455 G/A polymorphism were examined in a cohort of 545 apparently healthy individuals and those with atherothrombotic risk factors. A whole blood erythrocyte aggregation test was performed by using a simple slide test and image analysis. In men, EA levels and plasma fibrinogen levels were significantly higher in subjects carrying the -455 A allele compared to subjects with the -455 GG genotype. This association did not exist in women carrying the fibrinogen -455 A allele. The -455 GA/AA men presented significantly higher correlation between the plasma fibrinogen concentrations and EA. This observation raises the prospect of possible change in the functional properties of the -455 GA/AA fibrinogen, enhancing its ability to induce EH. This study suggests that the B beta-fibrinogen -455 A allele is related to EH in men only. Putative mechanism could be hyperfibrinogenemia and a functional change in the fibrinogen molecule that alters its ability to interact with red blood cells and supports the aggregability of these cells.