Polymorphisms in migraine-associated gene, atp1a2, and ischemic stroke risk in a biracial population: the genetics of early onset stroke study

Decreased content of ascorbic acid (vitamin C) in the brain of knockout mouse models of Na+,K+-ATPase-related neurologic disorders

Na⁺,K⁺-ATPase is a crucial protein responsible for maintaining the electrochemical gradients across the cell membrane. The Na⁺,K⁺-ATPase is comprised of catalytic α, β, and γ subunits. In adult brains, the α3 subunit, encoded by ATP1A3, is predominantly expressed in neurons, whereas the α2 subunit, encoded by ATP1A2, is expressed in glial cells. In foetal brains, the α2 is expressed in neurons as well. Mutations in α subunits cause a variety of neurologic disorders. Notably, the onset of symptoms in ATP1A2- and ATP1A3-related neurologic disorders is usually triggered by physiological or psychological stressors. To gain insight into the distinct roles of the α2 and α3 subunits in the developing foetal brain, whose developmental dysfunction may be a predisposing factor of neurologic disorders, we compared the phenotypes of mouse foetuses with double homozygous knockout of Atp1a2 and Atp1a3 (α2α3-dKO) to those with single knockout. The brain haemorrhage phenotype of α2α3-dKO was similar to that of homozygous knockout of the gene encoding ascorbic acid (ASC or vitamin C) transporter, SVCT2. The α2α3-dKO brain showed significantly decreased level of ASC compared with the wild-type (WT) and single knockout. We found that the ASC content in the basal ganglia and cerebellum was significantly lower in the adult Atp1a3 heterozygous knockout mouse (α3-HT) than in the WT. Interestingly, we observed a significant decrease in the ASC level in the basal ganglia and cerebellum of α3-HT in the peripartum period, during which mice are under physiological stress. These observations indicate that the α2 and α3 subunits independently contribute to the ASC level in the foetal brain and that the α3 subunit contributes to ASC transport in the adult basal ganglia and cerebellum. We propose that decreases in ASC levels may affect neural network development and are linked to the pathophysiology of ATP1A2- and ATP1A3-related neurologic disorders.

Investigating diagnostic sequencing techniques for CADASIL diagnosis

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a cerebral small vessel disease caused by mutations in the NOTCH3 gene. Our laboratory has been undertaking genetic diagnostic testing for CADASIL since 1997. Work originally utilised Sanger sequencing methods targeting specific NOTCH3 exons. More recently, next-generation sequencing (NGS)-based technologies such as a targeted gene panel and whole exome sequencing (WES) have been used for improved genetic diagnostic testing. In this study, data from 680 patient samples was analysed for 764 tests utilising 3 different sequencing technologies. Sanger sequencing was performed for 407 tests, a targeted NGS gene panel which includes NOTCH3 exonic regions accounted for 354 tests, and WES with targeted analysis was performed for 3 tests. In total, 14.7% of patient samples (n = 100/680) were determined to have a mutation. Testing efficacy varied by method, with 10.8% (n = 44/407) of tests using Sanger sequencing able to identify mutations, with 15.8% (n = 56/354) of tests performed using the NGS custom panel successfully identifying mutations and a likely non-NOTCH3 pathogenic variant (n = 1/3) identified through WES. Further analysis was then performed through stratification of the number of mutations detected at our facility based on the number of exons, level of pathogenicity and the classification of mutations as known or novel. A systematic review of NOTCH3 mutation testing data from 1997 to 2017 determined the diagnostic rate of pathogenic findings and found the NGS-customised panel increases our ability to identify disease-causing mutations in NOTCH3.

The Integrative Method Based on the Module-Network for Identifying Driver Genes in Cancer Subtypes

With advances in next-generation sequencing(NGS) technologies, a large number of multiple types of high-throughput genomics data are available. A great challenge in exploring cancer progression is to identify the driver genes from the variant genes by analyzing and integrating multi-types genomics data. Breast cancer is known as a heterogeneous disease. The identification of subtype-specific driver genes is critical to guide the diagnosis, assessment of prognosis and treatment of breast cancer. We developed an integrated frame based on gene expression profiles and copy number variation (CNV) data to identify breast cancer subtype-specific driver genes. In this frame, we employed statistical machine-learning method to select gene subsets and utilized an module-network analysis method to identify potential candidate driver genes. The final subtype-specific driver genes were acquired by paired-wise comparison in subtypes. To validate specificity of the driver genes, the gene expression data of these genes were applied to classify the patient samples with 10-fold cross validation and the enrichment analysis were also conducted on the identified driver genes. The experimental results show that the proposed integrative method can identify the potential driver genes and the classifier with these genes acquired better performance than with genes identified by other methods.

Dissecting the association between migraine and stroke

Migraine is a common disabling neurological disorder resulting from excessive cortical excitation and trigeminovascular afferent sensitization. In addition to aberrant neuronal processing, migraineurs are also at significant risk of vascular disease. Consequently, the impact of migraine extends well beyond the ictal headache and includes a well-documented association with acute ischemic stroke, particularly in young women with a history of migraine with aura. The association between migraine and stroke has been acknowledged for 40 years or more. However, examining the pathobiology of this association has become a more recent and critically important undertaking. The diversity of mechanisms underlying the association between migraine and stroke likely reflects the heterogenous nature of this disorder. Vasospasm, endothelial injury, platelet aggregation and prothrombotic states, cortical spreading depression, carotid dissection, genetic variants, and traditional vascular risk factors have been offered as putative mechanisms involved in migraine-related stroke risk. Assimilating these seemingly divergent pathomechanisms into a cogent understanding of migraine-related stroke will inform future studies and the development of new strategies for the prevention and treatment of migraine and stroke.

Gene polymorphism of rs556621 but Not rs11984041 is associated with the risk of large artery atherosclerotic stroke in a Xinjiang Uyghur population

BACKGROUND

Stroke is one of the main causes of death and adult chronic disability. Recently, 2 independent genome-wide association studies reported that the genetic variants (rs556621 and rs11984041) are significantly associated with large artery atherosclerosis (LAA).

METHODS

To determine whether these 2 variants are associated with the pathogenesis of LAA in stroke patients from the Xinjiang Uyghur autonomous region of China, both variants were evaluated in a series of 733 LAA stroke patients (434 Han and 299 Uyghur) and 725 age-, gender-, smoking-, alcohol habits- and ethnicity-matched controls (401 Han and 324 Uyghur).

RESULTS

For rs556621, significant differences in genotypic and allelic distributions were observed between Uyghur patients and controls (P = .045 for genotypic distribution, P = .042 for allelic distribution) but not in the Chinese Han cohort (P > .05). No significant differences were found in genotypic and allele distributions between patients and controls for rs11984041 in either the Chinese Han or Uyghur cohort (P > .05).

CONCLUSIONS

The variant rs556621 but not rs11984041 may increase susceptibility of LAA stroke in the Xinjiang Uyghur population.

A wide clinical phenotype spectrum in patients with ATP1A2 mutations

The clinical spectrum associated with ATP1A2 mutations is expanding and includes familial hemiplegic migraine, alternating hemiplegia of childhood, and epilepsy. We have identified a novel c.1766T>C. (Ile589Thr) heterozygous mutation in the ATP1A2 gene in a Saudi kindred with hemiplegic attacks and seizures. Our findings broaden the phenotypic spectrum of patients with ATP1A2 mutations.