Katalin Komlósi

Apolipoprotein A5 gene promoter region T-1131C polymorphism associates with elevated circulating triglyceride levels and confers susceptibility for development of ischemic stroke

The possible pathogenic role of triglycerides (TG) in the development of ischemic stroke is still under extensive investigation. Recently, apolipoprotein (apo)A5 gene promoter region T-1131C polymorphism has been shown to associate with elevated serum TG levels. In the current work, a total of 302 subjects were classified as being large vessel-associated, small vessel-associated, or belonging to a mixed group of ischemic stroke-affected patients. The level of TG was increased in all groups (p<0.01). The apoA5-1131C allele frequency was approximately twofold in all groups of stroke patients compared with the controls (5 vs 10–12%; p<0.05); and the apoA5-1131C allele itself was also found to associate with increased TG levels in all groups. In a multivariate logistic regression analysis model adjusted for differences in age, gender, serum cholesterol, hypertension, pressence of diabetes mellitus, smoking and drinking habits, and ischemic heart disease, a significantly increased risk of developing stroke disease was found in patients carrying the apoA5-1131C allele (p<0.05; odds ratio OR=2.1 [1.3–4.7]); this association was also proven for all subtypes of the stroke. The results presented here suggest that the apoA5-1131C allele is an independent risk factor for the development of stroke. Being that apoA5 gene is under the control of the peroxisome proliferator-activated receptor α, theoretically, the current observations also can have long-term therapeutic consequences.

Glycoprotein IIIA Gene (PIA) Polymorphism and Aspirin Resistance: Is There Any Correlation?

BACKGROUND: Platelet glycoprotein (GP) IIb/IIIa receptors play an inevitable role in platelet aggregation. The GP IIIa gene is polymorphic (PIA1/PIA2) and the presence of a PIA2 allele might be associated with an increased risk for acute coronary syndrome (ACS). OBJECTIVE: To examine the prevalence of the PIA2 allele in patients with ACS and in subjects with or without aspirin resistance. METHODS: The prevalence of the PIA2 allele was assessed in 158 patients with ACS and PIA2 compared with its prevalence in 199 healthy volunteers. The antiplatelet efficacy of aspirin was examined in all patients with ACS, as well as in 69 individuals who had suffered ischemic stroke and in 58 high-risk subjects without any known ischemic vascular events. RESULTS: PIA2 prevalence was significantly higher in patients with ACS (59/158) than in the control group (51/199; p < 0.05). Carriers of the PIA2 allele had a significantly higher risk of developing ACS, even after an adjustment to the risk factors (OR 5.74; 95% CI 1.75 to 18.8; p = 0.004). The occurrence of the PIA2 allele was significantly higher among patients with aspirin resistance than in subjects who demonstrated an appropriate response to the drug (allele frequencies, 0.21 vs 0.14; p < 0.05). All patients homozygous for the PIA2 allele had an inadequate platelet response to aspirin. CONCLUSIONS: Our results support the hypothesis that carriers of the PIA2 allele might have an increased risk for ACS. PIA2 homozygosity was associated with an inadequate response to aspirin therapy. Our data further suggest that patients with PIA2 allele homozygosity might benefit from antiplatelet therapy based on adenosine diphosphate antagonists throughout secondary treatment for prevention of ACS.

Phenotypic manifestations of the OCTN2 V295X mutation: sudden infant death and carnitine-responsive cardiomyopathy in Roma families.

In two non‐consanguineous Hungarian Roma (Gypsy) children who presented with cardiomyopathy and decreased plasma carnitine levels, we identified homozygous deletion of 17081C of the SLC22A5 gene that results in a frameshift at R282D and leads ultimately to a premature stop codon (V295X) in the OCTN2 carnitine transporter. Carnitine treatment resulted in dramatic improvement of the cardiac symptoms, echocardiographic, and EKG findings in both cases. Family investigations revealed four sudden deaths, two of them corresponded to the classic SIDS phenotype. In postmortem tissue specimens available from three of them we could verify the homozygous mutation. In liver tissue reserved from two patients lipid droplet vacuolization could be observed; the lipid vacuoles were located mainly in the peripherolobular regions of the acini. In the heart tissue signs of generalized hypertrophy and lipid vacuoles were seen predominantly in the subendocardial areas in both cases; some aggregates of smaller lipid vacuoles were separated, apparently by membranes. Review of all OCTN2 deficiency cases reported so far revealed that this is the first presentation of histopathology in classic familial sudden infant death syndrome (SIDS) with an established SLC22A5 mutation. In addition to the two affected homozygous cardiomyopathic children and three homozygous sudden death patients, the genetic analysis in 25 relatives showed 14 carriers. The mutant gene derived from five non‐consanguineous grandparents, each of them having 6–14 brothers and sisters. This alone suggests a wide ancestral spread of the mutation in certain Roma subpopulations.

Increased prevalence of platelet glycoprotein IIb/IIIa PLA2 allele in ischaemic stroke associated with large vessel pathology

INTRODUCTION Platelet glycoprotein IIb/IIIa is a membrane receptor with a central function in the platelet adhesion and ultimately in the thrombus formation. Two major variants of the gene encoding the IIIa subunit, called PLA1 (A1) and PLA2 (A2), have been identified in the general population. There are indications that the A2 allele can also be associated with acute thrombosis or stroke. The purpose of this study was to study the distribution of the A2 allele in different vascular subtypes of stroke disease. MATERIALS AND METHODS A total of 638 consecutive patients were analyzed and classified as having large vessel pathology (n=168) or a small vessel infarct (n=210). Localization of the vascular occlusions was deducted from analysis of the magnetic resonance imaging (MRI) scan results in stroke patients. The remainder patients were listed into a mixed vascular pathology group (n=167). Patients with other or poorly characterized stroke etiology were excluded from the study (n=93). RESULTS In the small vessel and mixed vascular pathology groups, the PLA2 allele frequency was similar to that in the controls. By contrast, PLA2 allele frequency was approximately two-fold higher in patients with large vessel pathology (23.3%) than in the stroke-free control subjects (11.7%, p<0.0005). Multivariate logistic regression analysis of data confirmed this association with an odds ratio (OR) of 2.9 (95% confidence interval [CI]: 1.6-4.9, p<0.0005). CONCLUSIONS These data suggest that the PLA2 allele is more frequent in brain infarcts associated with large-vessel occlusion.

Plasma carnitine ester profiles in Crohn's disease patients characterized for SLC22A4 C1672T and SLC22A5 G-207C genotypes.

Crohns disease (CD) is a chronic inflammatory bowel disorder caused by environmental and genetic factors. The purpose of this study was to analyse the possible influence of functional variants of genes of OCTN cation transporters on the carnitine ester profile of patients with CD. Genotyping for SLC22A4 1672C --> T, SLC22A5-207G --> C mutations and three common NOD2 variants (R702W, G908R and 1007finsC) were performed in 100 adult CD patients and in ninety-four healthy controls by direct sequencing. The carnitine ester profile was determined using ESI triple quadrupole tandem MS. Contrary to the NOD2/CARD15 mutations, none of the SLC variants showed increased prevalence in the CD group, the prevalence of TC haplotype did not differ between the patients and the controls. In the mixed group of CD patients the fasting propionyl- (0.243 (sem 0.008) v. 0.283 (sem 0.014) micromol/l), butyryl- (0.274 (sem 0.009) v. 0.301 (sem 0.013)) and isovalerylcarnitine (0.147 (sem 0.006) v. 0.185 (sem 0.009)) levels were decreased; while the level of octenoyl- (0.086 (sem 0.006) v. 0.069 (sem 0.005)), myristoleyl- (0.048 (sem 0.003) v. 0.037 (sem 0.003)), palmitoyl- (0.140 (sem 0.005) v. 0.122 (sem 0.004)) and oleylcarnitine (0.172 (sem 0.006) v. 0.156 (sem 0.008); P < 0.05 in all comparisons) were increased. After sorting the patients into SLC22A genotype-specific subgroups, no significant differences could be observed between them. The carnitine ester profile data suggest selective involvement of the carnitine esters in CD patients, probably due to their altered metabolism.

Lymphotoxin-α gene 252G allelic variant is a risk factor for large-vessel-associated ischemic stroke

A direct role of lymphotoxin-α (LTA) in promoting atherosclerotic plaque growth has been demonstrated recently. The different protein transcripts of the naturally occurring genetic variants of the LTA gene have been demonstrated to exhibit affected functions, and an allelic difference in binding to transcription factor(s) has also been suggested. The homozygous variant of LTA characterized by the intron 1 252A→G (252G) transition, which naturally coexists with an exon 3 804C→A (804A) single-nucleotide polymorphism (SNP), has been reported as a susceptibility gene for myocardial infarction. Because the atherosclerotic process is also an integral component in the pathogenesis of certain types of vascular stroke, we investigated the possible significance of the above SNPs in 353 ischemic stroke patients and 180 healthy controls. The homozygous LTA allele with the 252G and 804C SNPs occurred more frequently in stroke patients (13.9%) than in controls (7.20%, p<0.025). Specific subclassification of the patients revealed an accumulation of these SNPs in large-vessel, pathology-associated cerebral infarction (18.2%); multivariate logistic regression analysis of the data confirmed this association, with an odds ratio of 2.1 (95% confidence interval, 1.3–6.2; p<0.005). Elimination of all subjects with a history or evidence of ischemic heart disease, including myocardial infarction, did not affect this association. These data show that besides the role in the development of myocardial infarction, the homozygous carriage of the LTA allele with 252G and 804A SNPs is a novel susceptibility factor for largevesselassociated ischemic stroke.

Phenotypic Variants of the Deafness-Associated Mitochondrial DNA A7445G Mutation

A number of nuclear and mitochondrial mutations have been implicated in non-syndromic hearing loss. Among them, various mutations of mitochondrial Ser(UCN)-tRNA and 12S rRNA genes have been found to be associated with deafness; the A7445G mitochondrial DNA (mtDNA) in this group is unique, simultaneously affecting two different mitochondrial genes, encoding the Ser(UCN)-tRNA and the first subunit of cytochrome oxidase. Besides the hearing loss, it is mainly associated with palmoplantar keratoderma, though; different phenotypic associations have been reported. The current paper reviews the available PubMed reports on the A7445G mtDNA mutation, with special attention to the phenotypic variations. Further, a Hungarian family with the A7445G mutation is reported, in which analysis of both the affected and the non-affected members revealed the mutation in both homo- and heteroplasmic forms, independently of the hearing status of the subjects, a phenomenon previously not reported in other pedigrees. The female lineage represented a rare variant of the U4b haplogroup.

Determination of carnitine ester patterns during the second half of pregnancy, at delivery, and in neonatal cord blood by tandem mass spectrometry: complex and dynamic involvement of carnitine in the intermediary metabolism.

We studied plasma concentrations of free carnitine and 30 carnitine esters by electron spray ionization (ESI) tandem mass spectrometry in 37 pregnant women at the 20th and 30th weeks of gestation and at delivery, and in their neonates at birth, and in 22 age-matched nonpregnant women. The plasma levels of acetylcarnitine and carnitine esters with more than five carbons were significantly higher, whereas the concentration of free carnitine was significantly lower at term than at the 20th week of pregnancy (16.75 ± 0.89 versus 19.61 ± 1.25). Almost all of C2- to C12-carnitine esters were significantly lower, whereas C16- and C18-carnitines with in-chain modifications were significantly higher in mothers at delivery compared with nonpregnant women. Plasma levels of free carnitine and C2-, C3-, C4-, C5-, C6-, and C16-carnitines were significantly lower, while concentrations of carnitine esters with 8, 10, 12 and 18 carbons in the acyl chain as well as C14:1-, C14:2-, and C16:1-OH-carnitines were significantly higher in mothers at term than in their neonates. The data of the present study clearly show dynamic features of plasma carnitine profile during pregnancy and indicate an extraordinarily active participation of the carnitine in the intermediary metabolism both in the pregnant woman and in the neonate.

Angiotensin II type-1 receptor A1166C polymorphism is associated with increased risk of ischemic stroke in hypertensive smokers

Recent observations revealed a novel role of angiotensin-converting enzyme 2 and the angiotensin II type-1 receptor (AT1R) in lung injury, thereby extending knowledge about the functions of the angiotensin system. Angiotensin II, whose target is the AT1R, is a potent vasoconstrictor. Accordingly, an imbalance leading to enhanced activity of the angiotensin II-AT1R axis is postulated to contribute to both circulatory disturbances and lung injury. In this context, a functional single-nucleotide polymorphism, AT1R A1166C, which leads to enhanced responsiveness of the AT1R, has been postulated as a candidate susceptibility factor for ischemic stroke. The aim of our study was to investigate its occurrence in ischemic stroke and to analyze its possible synergistic associations with clinical risk factors. Genetic and clinical data on 308 consecutive patients with acutely developing ischemic stroke were analyzed. A total of 272 stroke and neuroimaging alteration-free subjects served as a control group. Univariate and logistic regression statistical approaches were used. Alone, the AT1R 1166C allele did not pose a risk of stroke. In hypertensive smokers, however, it was associated with an increased risk of ischemic stroke (OR 22.3, 95% CI 5.8–110.2, p<0.001). Further subgroup analysis revealed the same association for both small-vessel (OR 24.3, 95% CI 6.1–121.1, p<0.001) and large-vessel (OR 21.3, 95% CI 4.6–81.1, p<0.001) infarction. On a pathophysiological basis, our results suggest the possibility that the AT1R A1166C polymorphism might give rise to ischemic stroke indirectly via an unfavorable effect on the cardiorespiratory function.

Exome sequencing identifies Laing distal myopathy MYH7 mutation in a Roma family previously diagnosed with distal neuronopathy

We describe a Hungarian Roma family, originally investigated for autosomal dominant distal muscular atrophy. The mother started toe walking at 3 years and lost ambulation at age 27. Her three daughters presented with early steppage gait and showed variable progression. Muscle biopsies were nonspecific showing myogenic lesions in the mother and lesions resembling neurogenic atrophy in the two siblings. To identify the causative abnormality whole exome sequencing was performed in two affected girls and their unaffected father, unexpectedly revealing the MYH7 mutation c.4849_4851delAAG (p.K1617del) in both girls, reported to be causative for Laing distal myopathy. Sanger sequencing confirmed the mutation in the affected mother and third affected daughter. In line with variable severity in Laing distal myopathy our patients presented a more severe phenotype. Our case is the first demonstration of Laing distal myopathy in the Roma and the successful use of whole exome sequencing in obtaining a definitive diagnosis in ambiguous cases.