Beáta Bessenyei

Single nucleotide polymorphisms: aging and diseases

Differences of more than 3 million nucleotides can bee seen comparing the genomes of two individuals as a result of single nucleotide polymorphism (SNP). More and more SNPs can be identified and it seems that these alterations are behind of several biological phenomena. Personal differences in these nucleotides result for example in elevated disease susceptibilities, that is, certain nucleotides are more frequent in patients suffering from different diseases comparing to the healthy population. SNPs may cause substantial alterations in the cells, e.g. the enzyme activity of the respective gene changes, but in other cases the effects of the SNPs are not so pronounced. Later results indicate that SNPs can be rendered to individuals living a longer life than the average. Perhaps these results will not directly lead to the lengthening of the maximal life span; however, genes that play an important role in the aging process could be identified. In this respect SNPs are important factors in determining the information level of the cells of individuals which determines the maximal life span (I. Semsei On the nature of aging. Mech. Ageing Dev. 2000; 117: 93–108), in turn SNP is one of the factors that determine the aging process. Since there are certain age-related diseases, the discovery and the description of the SNPs as a function of age and diseases may result in a better understanding of the common roots of aging and those diseases.

On the Role of Aging in the Etiology of Autoimmunity

Several types of diseases, among others autoimmune illnesses, could be coupled with the general processes of aging. The two-edged sword of immune defense is directed on one side against environmental attacks and on the other against the body itself. However, one has to make a difference between normal (physiological) clearance and autoimmune diseases, although both sides of autoimmunity are influenced by the general processes of senescence. Aging of the thymus seems to be one of the key elements in the etiology of autoimmunity, although other cell types and their aging also play a substantial role in this process. Spontaneous genetic instability, acquired genetic mutations due to aging and the age-related alterations in the information level of the body may together be important elements in the pathomechanism of both physiological autoimmunity and autoimmune diseases. Nevertheless, physiological autoimmunity seems to be directed mostly by natural factors (such as aging and apoptosis) but primary autoimmune diseases may be caused by genetic instability that is enhanced by aging as well.

Lissencephaly and band heterotopia: LIS1, TUBA1A, and DCX mutations in Hungary

The spectrum of lissencephaly ranges from absent (agyria) or decreased (pachygyria) convolutions to less severe malformation known as subcortical band heterotopia. Mutations involving LIS1 and TUBA1A result in the classic form of lissencephaly, whereas mutations of the DCX gene cause lissencephaly in males and subcortical band heterotopia in females. This report describes the clinical manifestations and imaging and genetic findings in 2 boys with lissencephaly and a girl with subcortical band heterotopia. An ovel mutation (c.83_84delAT, p.Tyr28Phefs*31) was identified in LIS1 in 1 of the boys with lissencephaly and another novel mutation (c.200delG, p.Ile68Leufs*87) was found in DCX in the girl with subcortical band heterotopia. The mutations appeared in the first half of the genes and are predicted to result in truncated proteins. A mutation was found in the TUBA1A gene (c.1205G>A, p.Arg402His) in the other boy. This mutation affects the folding of tubulin heterodimers, changing the interactions with proteins that bind microtubules.

IL-10 promoter -1082 polymorphism is associated with elevated IL-10 levels in control subjects but does not explain elevated plasma IL-10 observed in Sjögren's syndrome in a Hungarian cohort.

The aim of this study was to investigate the frequency of the −1082 polymorphism of the interleukin‐10 (IL‐10) gene and the soluble IL‐10 levels in Hungarian primary Sjögrens syndrome (SS) patients. Ninety‐nine SS patients and 135 healthy volunteers were examined. Samples were analysed by the PCR restriction fragment length polymorphism method, and IL‐10 plasma levels were assesed by a commercial enzyme‐linked immunosorbent assay. IL‐10 plasma levels were higher in the primary SS patients (36.4 ± 57.5 pg/ml, n = 99) compared with the healthy subjects (9.9 ± 20.3 pg/ml, n = 135, P = 10−6). The elevated IL‐10 phenotype of SS patients was not associated with increased G allele frequency as reported earlier, while in the control group, we found higher IL‐10 levels among the subjects who were carriers of the GG genotype (17.7 ± 23.2 pg/ml) as compared with the other two genotype carriers (AA 8.98 ± 16.5 and GA 8.5 ± 21.1 pg/ml, P = 0.01). Our data do not support previous observations indicating an association between deregulated IL‐10 secretion in SS and higher G allele frequency. However, the results clearly demonstrate that GG homozygosity is associated with elevated IL‐10 levels in apparently healthy subjects, but this cannot account for the IL‐10‐related specific disease features observed in SS. Thus, other genetic factors contribute to the clinical spectrum of this heterogeneous disease at least in the Hungarian population.

Association between the epstein-barr virus and hodgkin's lymphoma in the north-eastern part of Hungary : Effects on therapy and survival

This retrospective study included 109 patients with Hodgkin’s lymphoma (HL; 45 females, 64 males). In 47 of the 109 HL patients (43%), immunohistochemical analysis of their formalin-fixed, paraffin-embedded histologic samples revealed Epstein-Barr virus (EBV) by latent membrane protein (LMP) 1. The highest virus association (50%) was found with the mixed cellularity histologic subtype, especially in patients aged 11–20 and >50 years. Virus positivity in nodular sclerosis was 35% (negative cases accumulated in patients aged 15–30 years). Regarding clinical stages, histologic subtypes, general symptoms, treatments employed and response to treatment, the EBV-positive group was not significantly different from the virus-negative group. During the mean follow-up time of 83 months (9–300 months), the overall or event-free survival of EBV-negative patients was more favorable than that of EBV-positive patients, although the difference was not significant (p = 0.16 and p = 0.24, respectively). EBV infection may be involved in the pathogenesis of HL in our Hungarian study cohort, but it does not significantly affect clinical symptoms, therapeutic results or complete and event-free survival of HL patients.

New mutations in the ATM gene and clinical data of 25 AT patients

Ataxia telangiectasia (AT) is an autosomal recessive disorder characterized by cerebellar degeneration, immunodeficiency, oculocutaneous telangiectasias, chromosomal instability, radiosensitivity, and cancer predisposition. The gene mutated in the patients, ATM, encodes a member of the phosphatidylinositol 3-kinase family proteins. The ATM protein has a key role in the cellular response to DNA damage. Truncating and splice site mutations in ATM have been found in most patients with the classical AT phenotype. Here we report of our extensive ATM mutation screening on 25 AT patients from 19 families of different ethnic origin. Previously unknown mutations were identified in six patients including a new homozygous missense mutation, c.8110T>C (p.Cys2704Arg), in a severely affected patient. Comprehensive clinical data are presented for all patients described here along with data on ATM function generated by analysis of cell lines established from a subset of the patients.

Blepharophimosis mental retardation syndrome Say-Barber/Biesecker/Young-Simpson type – New findings with neuroimaging†

We report on a female patient with blepharophimosis mental retardation syndrome of Say/Barber/Biesecker/Young‐Simpson (SBBYS) type. Main findings in her were marked developmental delay, blepharophimosis, ptosis, cleft palate, external auditory canal stenosis, small and malformed teeth, hypothyroidism, hearing impairment, and joint limitations. We performed diffusion tensor magnetic resonance imaging (MRI) and tractography of the brain which showed inappropriate myelination and disturbed white matter integrity. Cytogenetic analysis, subtelomeric fluorescence in situ hybridization and comparative genomic hybridization failed to identify an abnormality. It remains uncertain whether the MRI findings are specific to the present patient or form part of the SBBYS syndrome.

Detection of subtelomeric chromosomal rearrangements in idiopathic mental retardation

A kromoszomak szubtelomerikus regioi genben gazdag teruletek, atrendeződesuk hagyomanyos kromoszomaanalizissel nem detektalhato. Mivel a mentalis retardaciok kozel 7%-aert felelősek, kimutatasuk diagnosztikai szempontbol jelentős, es lehetőseget nyujt az ismetlődes megakadalyozasara is. A kimutatasukra alkalmas modszerek egyike a szubtelomerikus fl uoreszcencia in situ hibridizacio. Otvenkilenc idiopathias mentalisan retardalt beteg kozul 35 kozepes/sulyos ertelmi fogyatekost valasztottunk ki a nemzetkozi irodalomban ajanlott kriteriumok alapjan. Kozuluk 6 beteg eseteben mutattunk ki szubtelomerikus aberraciot, 5 familiaris (ket csalad), egy de novo esetnek bizonyult. Huszonkilenc betegben szubtelomerikus kromoszomaatrendeződest nem igazoltunk. A 6 beteg kozul kettőben 8pter deleciot es 12pter duplikaciot, haromban 21qter deleciot es 10pter duplikaciot azonositottunk kiegyensulyozatlan transzlokacio formajaban. Egy betegnel de novo keletkezett 3qter deleciot detektaltunk. Az elteresek eredetenek tisztazasa soran 12 egeszseges csaladtag kozul ot bizonyult kiegyensulyozott transzlokaciohordozonak. Az irodalmi adatokkal osszhangban megallapitottuk, hogy a fenotipust a delecio es a duplikacio merete, valamint transzlokaciok eseten az erintett partner kromoszomak egyuttesen hatarozzak meg.Subtelomeric regions of chromosomes are rich in genes; their rearrangements cannot be identified by traditional chromosome analysis. Since these subtelomeric aberrations are responsible for about 7% of cases with mental retardation, their detection is important both from the diagnostic point of view and to prevent recurrence in the family. Subtelomeric chromosomal alterations can be detected by fluorescence in situ hybridization. Based on international criteria, 35 out of 59 patients with mental retardation have been selected. Subtelomeric rearrangements were revealed in 6 patients (5 familial cases, 1 new onset) whereas the subtelomeric FISH result was normal in 29 cases. Deletion of 8pter and duplication of 12pter were detected in 2 patients, while a deletion of 21qter and duplication of the 10pter due to an unbalanced translocation were found in 3 other cases. Finally, a new onset deletion of 3qter was observed in 1 patient. In order to clarify the origin of chromosome aberrations, 12 healthy family members were also examined, 5 of them carried balanced translocations. We concluded that the phenotype is mostly influenced by the size of regions involved in deletion/duplication and - in case of translocations - by the associated chromosomal abnormalities.

UVB light and 17-β-estradiol have different effects on the mRNA expression of Ro/SSA and La/SSB autoantigens in HaCaT cells

Abstract Antibodies produced against the Ro/SSA and La/SSB autoantigens are not only of diagnostic value but they may even play a role in the pathogenesis of several autoimmune diseases (Sjögren’s syndrome, subacute cutaneous lupus erythematosus, neonatal lupus erythematosus and systemic lupus erythematosus). Among other factors, ultraviolet (UV) radiation and also the hormonal milieu are well-known cofactors in the pathogenesis of these autoimmune diseases. The goal of our research was to study the possible alterations in mRNA levels of three different Ro antigens and that of two La species produced by alternative splicing in transformed human keratinocytes (HaCaT cells) after UVB irradiation and after 17-β-estradiol treatment. The polymerase chain reaction technique was used to determine the mRNA levels of the Ro and La species after 24, 48, and 72 h of irradiation. The mRNA levels of calreticulin increased as a function of time after UV irradiation but the mRNA levels of 52 kDa and 60 kDa Ro mRNAs were unaltered. After treating the cells with 17-β-estradiol, there was no change observed in the levels of Ro mRNAs or La exon 1 mRNA, but a gradual decrease was noted in the mRNA levels of La exon 1′. The importance of alterations in the ratio of La exon 1 to exon 1′ is supported by the observations in patients with Sjögren’s syndrome, and our results strengthen the notion that the Ro and La antigens participate in the pathogenesis of different autoimmune diseases.

Variable expressivity of pfeiffer syndrome in a family with FGFR1 p.Pro252Arg mutation

Pfeiffer syndrome is an autosomal dominant disorder classically characterized by craniosynostosis, facial dysmorphism and limb anomalies. The majority of cases are caused by mutations in the fibroblast growth factor receptor 2 (FGFR2) gene. A specific, rare mutation p.Pro252Arg, located between the second and third extracellular immunoglobulin‐like domain of FGFR1, is associated with mild clinical signs. We report on a three‐generation family with five members having a heterozygous FGFR1 p.Pro252Arg mutation. Phenotypic features within the family showed high variability from the apparently normal skull and limbs to the characteristic brachycephaly and digital anomalies. The typical features of Pfeiffer syndrome appeared only in the third generation allowing us to unveil the syndrome in several further family members in two previous generations. Variable expressivity can complicate the recognition of Pfeiffer syndrome, principally the mild type 1, requiring careful phenotyping and genetic counseling.