Ischaemic strokes in patients with pulmonary arteriovenous malformations and hereditary hemorrhagic telangiectasia: associations with iron deficiency and platelets.

<div><p>Background</p><p>Pulmonary first pass filtration of particles marginally exceeding ∼7 µm (the size of a red blood cell) is used routinely in diagnostics, and allows cellular aggregates forming or entering the circulation in the preceding cardiac cycle to lodge safely in pulmonary capillaries/arterioles. Pulmonary arteriovenous malformations compromise capillary bed filtration, and are commonly associated with ischaemic stroke. Cohorts with CT-scan evident malformations associated with the highest contrast echocardiographic shunt grades are known to be at higher stroke risk. Our goal was to identify within this broad grouping, which patients were at higher risk of stroke.</p><p>Methodology</p><p>497 consecutive patients with CT-proven pulmonary arteriovenous malformations due to hereditary haemorrhagic telangiectasia were studied. Relationships with radiologically-confirmed clinical ischaemic stroke were examined using logistic regression, receiver operating characteristic analyses, and platelet studies.</p><p>Principal Findings</p><p>Sixty-one individuals (12.3%) had acute, non-iatrogenic ischaemic clinical strokes at a median age of 52 (IQR 41–63) years. In crude and age-adjusted logistic regression, stroke risk was associated not with venous thromboemboli or conventional neurovascular risk factors, but with low serum iron (adjusted odds ratio 0.96 [95% confidence intervals 0.92, 1.00]), and more weakly with low oxygen saturations reflecting a larger right-to-left shunt (adjusted OR 0.96 [0.92, 1.01]). For the same pulmonary arteriovenous malformations, the stroke risk would approximately double with serum iron 6 µmol/L compared to mid-normal range (7–27 µmol/L). Platelet studies confirmed overlooked data that iron deficiency is associated with exuberant platelet aggregation to serotonin (5HT), correcting following iron treatment. By MANOVA, adjusting for participant and 5HT, iron or ferritin explained 14% of the variance in log-transformed aggregation-rate (p = 0.039/p = 0.021).</p><p>Significance</p><p>These data suggest that patients with compromised pulmonary capillary filtration due to pulmonary arteriovenous malformations are at increased risk of ischaemic stroke if they are iron deficient, and that mechanisms are likely to include enhanced aggregation of circulating platelets.</p></div

Update of variants identified in the pancreatic β-cell K ATP channel genes KCNJ11 and ABCC8 in individuals with congenital hyperinsulinism and diabetes

The most common genetic cause of neonatal diabetes and hyperinsulinism is pathogenic variants in ABCC8 and KCNJ11. These genes encode the subunits of the β-cell ATP-sensitive potassium channel, a key component of the glucose-stimulated insulin secretion pathway. Mutations in the two genes cause dysregulated insulin secretion; inactivating mutations cause an oversecretion of insulin, leading to congenital hyperinsulinism, whereas activating mutations cause the opposing phenotype, diabetes. This review focuses on variants identified in ABCC8 and KCNJ11, the phenotypic spectrum and the treatment implications for individuals with pathogenic variants.This article is freely available via Open Access. Click on the publisher URL to access it via the publisher's site.P30 DK020595/NH/NIH HHS/United States K23 DK094866/NH/NIH HHS/United States R03 DK103096/NH/NIH HHS/United States 1-11-CT-41/American Diabetes Association/International R01 DK104942/DK/NIDDK NIH HHS/United States WT_/Wellcome Trust/United Kingdom WT098395/Z/12/Z/WT_/Wellcome Trust/United Kingdom UL1 TR000430/NH/NIH HHS/United States P30 DK020595/DK/NIDDK NIH HHS/United States UL1 TR000430/TR/NCATS NIH HHS/United States 1-17-JDF-008/American Diabetes Association/International 105636/Z/14/Z/WT_/Wellcome Trust/United Kingdom 110675/European Association for the Study of Diabetes-Novo Nordisk/International 16/0005407/DUK_/Diabetes UK/United Kingdom R01 DK104942/NH/NIH HHS/United States R03 DK103096/DK/NIDDK NIH HHS/United States K23 DK094866/DK/NIDDK NIH HHS/United Statespublished version, accepted version (12 month embargo), submitted versio

Genomic characterization of five deletions in the LDL receptor gene in Danish Familial Hypercholesterolemic subjects

BACKGROUND: Familial Hypercholesterolemia is a common autosomal dominantly inherited disease that is most frequently caused by mutations in the gene encoding the receptor for low density lipoproteins (LDLR). Deletions and other major structural rearrangements of the LDLR gene account for approximately 5% of the mutations in many populations. METHODS: Five genomic deletions in the LDLR gene were characterized by amplification of mutated alleles and sequencing to identify genomic breakpoints. A diagnostic assay based on duplex PCR for the exon 7 – 8 deletion was developed to discriminate between heterozygotes and normals, and bioinformatic analyses were used to identify interspersed repeats flanking the deletions. RESULTS: In one case 15 bp had been inserted at the site of the deleted DNA, and, in all five cases, Alu elements flanked the sites where deletions had occurred. An assay developed to discriminate the wildtype and the deletion allele in a simple duplex PCR detected three FH patients as heterozygotes, and two individuals with normal lipid values were detected as normal homozygotes. CONCLUSION: The identification of the breakpoints should make it possible to develop specific tests for these mutations, and the data provide further evidence for the role of Alu repeats in intragenic deletions

Predominance of a 6 bp deletion in exon 2 of the LDL receptor gene in Africans with familial hypercholesterolaemia

The original publication is available at http://jmg.bmj.com/In South Africa, the high prevalence of familial hypercholesterolaemia (FH) among Afrikaners, Jews, and Indians as a result of founder genes is in striking contrast to its reported virtual absence in the black population in general. In this study, the molecular basis of primary hypercholesterolaemia was studied in 16 Africans diagnosed with FH. DNA analysis using three screening methods resulted in the identification of seven different mutations in the coding region of the low density lipoprotein (LDLR) gene in 10 of the patients analysed. These included a 6 bp deletion (GCGATG) accounting for 28% of defective alleles, and six point mutations (D151H, R232W, R385Q, E387K, P678L, and R793Q) detected in single families. The Sotho patient with missense mutation R232W was also heterozygous for a de novo splicing defect 313+1G→A. Several silent mutations/polymorphisms were detected in the LDLR and apolipoprotein B genes, including a base change (g→t) at nucleotide position −175 in the FP2 LDLR regulatory element. This promoter variant was detected at a significantly higher (p<0.05) frequency in FH patients compared to controls and occurred in cis with mutation E387K in one family. Analysis of four intragenicLDLR gene polymorphisms showed that the same chromosomal background was identified at this locus in the four FH patients with the 6 bp deletion. Detection of the 6 bp deletion in Xhosa, Pedi, and Tswana FH patients suggests that it is an ancient mutation predating tribal separation approximately 3000 years ago.Harry and Doris Crossley FoundationSouth African Medical Research CouncilUniversity of StellenboschBritish Heart Foundation (grant no PG/96013)Publisher's versio

The Etiology of Multiple Sclerosis: Genetic Evidence for the Involvement of the Human Endogenous Retrovirus HERV-Fc1

We have investigated the role of human endogenous retroviruses in multiple sclerosis by analyzing the DNA of patients and controls in 4 cohorts for associations between multiple sclerosis and polymorphisms near viral restriction genes or near endogenous retroviral loci with one or more intact or almost-intact genes. We found that SNPs in the gene TRIM5 were inversely correlated with disease. Conversely, SNPs around one retroviral locus, HERV-Fc1, showed a highly significant association with disease. The latter association was limited to a narrow region that contains no other known genes. We conclude that HERV-Fc1 and TRIM5 play a role in the etiology of multiple sclerosis. If these results are confirmed, they point to new modes of treatment for multiple sclerosis

Novel KRAS Gene Mutations in Sporadic Colorectal Cancer

In this article, we report 7 novel KRAS gene mutations discovered while retrospectively studying the prevalence and pattern of KRAS mutations in cancerous tissue obtained from 56 Saudi sporadic colorectal cancer patients from the Eastern Province.Genomic DNA was extracted from formalin-fixed, paraffin-embedded cancerous and noncancerous colorectal tissues. Successful and specific PCR products were then bi-directionally sequenced to detect exon 4 mutations while Mutector II Detection Kits were used for identifying mutations in codons 12, 13 and 61. The functional impact of the novel mutations was assessed using bioinformatics tools and molecular modeling.KRAS gene mutations were detected in the cancer tissue of 24 cases (42.85%). Of these, 11 had exon 4 mutations (19.64%). They harbored 8 different mutations all of which except two altered the KRAS protein amino acid sequence and all except one were novel as revealed by COSMIC database. The detected novel mutations were found to be somatic. One mutation is predicted to be benign. The remaining mutations are predicted to cause substantial changes in the protein structure. Of these, the Q150X nonsense mutation is the second truncating mutation to be reported in colorectal cancer in the literature.Our discovery of novel exon 4 KRAS mutations that are, so far, unique to Saudi colorectal cancer patients may be attributed to environmental factors and/or racial/ethnic variations due to genetic differences. Alternatively, it may be related to paucity of clinical studies on mutations other than those in codons 12, 13, 61 and 146. Further KRAS testing on a large number of patients of various ethnicities, particularly beyond the most common hotspot alleles in exons 2 and 3 is needed to assess the prevalence and explore the exact prognostic and predictive significance of the discovered novel mutations as well as their possible role in colorectal carcinogenesis

Estandarización del cariotipo del visón americano ("Mustella Viso")

El cariotipo del visón consta de 14 autosomas y un par de cromosomas sexuales. Se propone un sistema en el cual la fila 1 consta de cinco grandes cromosomas metacéntricos ordenados por tamaño, la fila 2 consta de cinco cromosomas submetacéntricos ordenados por tamaño y la fila 3 consta de tres acrocéntricos ordenados por tamaño. La identificación de los cromosomas individuales está basada en bandeos R-, Q- y N. Se propone un sistema de numeración para las bandas individuales que cubre un total aproximado de 100 bandas. Se presentan resultados de hibridación in situ para más de 50 cósmidos seleccionados por contener repetición de dinucleótidos. Mediante esas hibridaciones se localiza un marcador sobre todos los cromosomas. Cinco cósmidos muestran resultados de fuerte hibridación en centrómeros, incluyendo la región del organizador nuclear y el cromosoma Y. Resultados mas detallados pueden apreciarse en el servidor http//www.husdir.kvl.dkfmink.htm

Estandarización del cariotipo del visón americano ("Mustella Viso")

El cariotipo del visón consta de 14 autosomas y un par de cromosomas sexuales. Se propone un sistema en el cual la fila 1 consta de cinco grandes cromosomas metacéntricos ordenados por tamaño, la fila 2 consta de cinco cromosomas submetacéntricos ordenados por tamaño y la fila 3 consta de tres acrocéntricos ordenados por tamaño. La identificación de los cromosomas individuales está basada en bandeos R-, Q- y N. Se propone un sistema de numeración para las bandas individuales que cubre un total aproximado de 100 bandas. Se presentan resultados de hibridación in situ para más de 50 cósmidos seleccionados por contener repetición de dinucleótidos. Mediante esas hibridaciones se localiza un marcador sobre todos los cromosomas. Cinco cósmidos muestran resultados de fuerte hibridación en centrómeros, incluyendo la región del organizador nuclear y el cromosoma Y. Resultados mas detallados pueden apreciarse en el servidor http//www.husdir.kvl.dkfmink.htm