Search

AbstractIn an effort to better understand the complex genetic background of Alzheimer’s disease (AD) we performed high-coverage whole-exome sequencing of a DNA pool assembled of 66 Bulgarian AD patients. We focused our analysis on genes demonstrated to have association with AD in previous studies, i.e. PSEN1, PSEN2, APP, APOE, TREM2, HFE, CLU and CR1. In these genes, we established six pathogenic/likely pathogenic variants in the sequenced pool, three common and three rare. Two of these variants showed statically non-significant difference between Bulgarian AD patients and Bulgarian control exomes, the hemochromatosis variant rs104894002 (HFE) and rs7412 (APOE), which, notwithstanding its pathogenicity score, has putative protective role against AD. Three of the remaining four pathogenic/likely pathogenic variants were estimated to significantly differ in frequency between the analyzed AD patient pool and controls. These are the rs429358 (APOE) polymorphism, a well-established risk factor for Alzheimer’s disease, the rs28936380 (PSEN2) and rs104894002 (TREM2), also ascertained to be associated with AD. The performed study validates the role of three pathogenic/likely pathogenic variants in AD related genes in the multifaceted genetic etiology of Alzheimer’s disease.

AbstractPublicly available genome-wide data, sequenced from 2730 ancient human samples were analyzed for genetic predisposition to malignancy. The temporal and spatial incidence of risk variants for cancer diseases in ancient genomes was recorded, allowing for estimates of their frequencies in ancient human communities. We identified 55 risk alleles associated with oncological conditions in the screened ancient samples. For further analysis, we selected three variants conclusively deemed to entail pathogenic effect, the VHL gene’s rs28940298, the TP53 gene’s rs78378222 and the BRCA2 gene’s rs11571833. The contemporary population frequency of these three variants is lower, or similar, to their estimated frequency in ancient human communities, indicating that they might have been subject to negative selection. This is also suggested by their temporal dynamics during the last 10000 years, which show an overall temporal decrease in population frequency. The oldest samples in which these three variants were established testify their ancient origin, including the presence of TP53 gene’s rs78378222 variant in 50000 BP old Neanderthal and Denisovan genomes. Our results demonstrate the presence of cancer-causing mutations in ancient human communities and suggest that they differed in frequency among ancient populations as they do among contemporary ones. Data on germline mutations in tumour suppressor genes in ancient human genomes are scarce and their historic prevalence gives insights into the evolution of predisposition to cancer disease and hence helps advance paleogenomic medicine.

Summary: Genetics have nominated many schizophrenia risk genes and identified convergent signals between schizophrenia and neurodevelopmental disorders. However, functional interpretation of the nominated genes in the relevant brain cell types is often lacking. We executed interaction proteomics for six schizophrenia risk genes that have also been implicated in neurodevelopment in human induced cortical neurons. The resulting protein network is enriched for common variant risk of schizophrenia in Europeans and East Asians, is down-regulated in layer 5/6 cortical neurons of individuals affected by schizophrenia, and can complement fine-mapping and eQTL data to prioritize additional genes in GWAS loci. A sub-network centered on HCN1 is enriched for common variant risk and contains proteins (HCN4 and AKAP11) enriched for rare protein-truncating mutations in individuals with schizophrenia and bipolar disorder. Our findings showcase brain cell-type-specific interactomes as an organizing framework to facilitate interpretation of genetic and transcriptomic data in schizophrenia and its related disorders.

Targeted therapy with tyrosine kinase inhibitors (TKIs) was introduced for the suppression of BCR-ABL fusion protein in chronic myelogenic leukemia (CML) more than 50 years ago. The introduction of TKI was an elegant way to gain control over the disease and opened a horizon to the development of new and safer drugs to better manage the disease progression in CML patients. Although Imatinib (the first TKI) was highly effective for the treatment of CML, the lack of response in some patients and the development of resistance led to the introduction of a second-generation TKI, like Nilotinib (Tasigna®). This study aimed to show the molecular response to Nilotinib after a long-term monitoring of CML patients. We analyzed the molecular response rate of twenty-seven CML patients admitted to the Hematology Ward. All of them were subjected to multiple control measurements of Philadelphia chromosome once in at least three months’ period between January 2017 and March 2020. All patients showed a remarkable decrease in the level of the fusion gene’s expression. The highest drop in the expression level was detected after the first dose admission. Some of the patients even reached an expression of BCR-ABL below the detection limit and it was maintained stably low during further examinations. In our patients with CML, Nilotinib resulted in prolonged and deep molecular response. The expression level of BCR-ABL fusion gene showed a substantial decrease immediately after Nilotinib treatment, revealed as early as the third month of therapy.

Contemporary genetic methods have not yet solved the ‘missing heritability’ problem of complex diseases such as Alzheimer’s disease (AD). The impact of rare or less common variation on human complex diseases and traits remains to date barely investigated. In this study rare population variants detected using whole-exome sequencing were employed to examine how molecular pathways are prioritized in four groups: Alzheimer’s disease (AD) patients, Frontotemporal dementia (FTD) patients, young and healthy individuals and centenarians. The set of prioritized genes in AD patients associated with Semaphorin interactions pathways, contrasting with the results of the other groups. We identified rare pathogenic, likely pathogenic and variants of unknown significance in these prioritized genes in AD patients. The results of this study offer evidence that semaphorin pathways play a role in AD genetic etiology.

Recent advances in biomedicine are opening the door to new approaches, and treatment and prevention are being transformed by novel medicines based on genetic engineering, innovative cell-based therapies and tissue-engineered products, and combinations of a medical device with embedded cell or tissue components. These advanced therapy medicinal products (ATMPs) hold one of the keys to making a reality of genuinely personalised medicine. There are an estimated 450 companies across the globe working on the development of gene therapies and more than 1,000 clinical trials underway worldwide, and some 20–30 new ATMPs filings are expected in Europe annually over the next 5 years. But challenges confront the sector, complicating the translation from research into patient access. Scientific, clinical development and regulatory issues are compounded by limited experience with clinical and commercial use, limited manufacturing know-how, high costs, and difficulties in accessing development funding and investment. Pricing and reimbursement and market access issues are an additional challenge, particularly in Europe, where unfamiliarity with the technology and uncertainty over the use of real-world evidence induce caution among clinicians, health technology assessment bodies and payers. There is a need for a review of the suitability of the regulatory and market access framework for these products, focused development of data, public/private partnerships, and fuller collaboration governments, doctors, insurers, patients, and pharmaceutical companies. This paper makes specific recommendations for all stakeholders, ranging from early dialogue on potential products, linking of clinical data and patient registries or standardisation of control frameworks, to a comprehensive approach to evidence generation, assessment, pricing, and payment for ATMPs.

Many bladder cancer (BC) patients with early disease are asymptomatic and diagnosed at advanced stage when the therapeutic options are limited. This necessitates the development of reliable predictive molecular biomarkers that will ensure a positive therapeutic response in every patient. The aim of this study was to screen for alterations in gene expression levels related to drug sensitivity and resistance that may be further explored as potential predictive therapeutic biomarkers. Gene expression analysis of the 168 genes from two panels for Cancer drug resistance and metabolism (PAHS004) and Cancer Drug Targets (PAHS507z) was performed. A total of 47 transitorial cell bladder cancer samples of stage pTa, pT1, pT2 were investigated using the pooling method, which allows reducing the effect of biological variation and detecting only significant expression changes. Differential gene expression was calculated using the ΔΔCt method with GPDH as a housekeeping gene. The 4.0-fold change in gene expression was used as the cut-off threshold to determine upregulation or downregulation compared to normal bladder tissue (negative control). Significance of the differences in the expression profiles was assessed by nonparametric one-way analysis of variance (ANOVA) with Dunn’s multiple comparison tests and Mann-Witney test. We demonstrated a correlation of tumor invasion and several up-regulated genes related to chemotherapy resistance. For the first time, this study demonstrated overexpression of CDK8, CDK9, FIGF, HDAC11, IGF1 and PDGFRA genes in muscle-invasive bladder carcinomas. These genes and their proteins could be used as potential biomarkers for bladder cancer progression or prospective therapeutic targets.

Overweight and obesity are serious and an ever-growing problem in modern society. It is a major risk factors for a number of chronic diseases, including type 2 diabetes, cardiovascular diseases and cancer. Obesity is a complex condition resulting from the interaction of a range of genetic and environmental factors. The aim of this study was to identify genetic markers predisposing to, and molecular pathways associated with, obesity in Bulgarian healthy individuals. Whole-exome sequencing was performed on two DNA pools: one constructed of 32 Bulgarian centenarians and one of 61 young healthy individuals, both with normal BMI, and allele frequencies of detected variants were estimated for each pool. Centenarians were chosen as their exome could be considered ‘golden standard’ for health and longevity, including being free of genetic variants predisposing to obesity. The young individuals group was chosen so variants predisposing to obesity after adolescence can be evaluated when compared to the centenarians. Of all variants designated to be associated with obesity by the database DisGeNET, only 17% were discovered in the studied pools. Using the platform ToppGene, we identified three over-represented pathways based on genes with variants showing significant prelevance in allele frequency in the young individuals group. These three pathways were all G-protein coupled receptor associated pathways: the GPCR ligand binding pathway, the G alpha (s) signalling events pathway and the Class A/1 (Rhodopsin-like receptors) pathway. Understanding the genetic etiology of obesity in different populations is instrumental in developing pharmacological targets for population-specific obesity therapies.

Genetic disease burden in ancient communities has barely been evaluated despite an ever expanding body of ancient genomes becoming available. In this study, we inspect 2729 publicly available ancient genomes (100 BP-52000 BP) for the presence of pathogenic variants in 32643 disease-associated loci. We base our subsequent analyses on 19 variants in seven genes-PAH, EDAR, F11, HBB, LRRK2, SLC12A6 and MAOA, associated with monogenic diseases and with well-established pathogenic impact in contemporary populations. We determine 230 homozygote genotypes of these variants in the screened 2729 ancient DNA samples. Eleven of these are in the PAH gene (126 ancient samples in total), a gene associated with the condition phenylketonuria in modern populations. The variants examined seem to show varying dynamics over the last 10000 years, some exhibiting a single upsurge in frequency and subsequently disappearing, while others maintain high frequency levels (compared to contemporary population frequencies) over long time periods. The geographic distribution and age of the ancient DNA samples with established pathogenic variants suggests multiple independent origin of these variants. Comparison of estimates of the geographic prevalence of these variants from ancient and contemporary data show discontinuity in their prevalence and supports their recurrent emergence. The oldest samples in which a variant is established might give an indication of their age and place origin, and an EDAR gene pathogenic variant was established in a sample estimated to be 33210-32480 calBCE. Knowledge about the historical prevalence of variants causing monogenic disorders provides insight on their emergence, dynamics and spread.

Coronary heart disease (CHD) is a major cause of mortality and morbidity in Europe. CHD is usually caused by atherosclerosis. Despite extensive studies that have identified a large number of genetic variants, strong evidence of association with CHD are not easily replicable in different populations. Two DNA pools were constructed: one with 32 Bulgarian centenarians and one with 61 young healthy Bulgarian individuals. The pools were whole-exome sequenced and variants were annotated and quality filtered (89,810 filtered variants). Allele frequencies were estimated and Fisher’s exact test was used to evaluate the significance of allele frequency differences between the two pools. Two publicly available databases, Ensembl and DisGeNET, were used as a source of 2025 CHD-associated variants (CHD-AVs). These single nucleotide polymorphisms were screened in our data and 158 variants in 133 genes were found. ToppGene pathways analysis of genes called in both pools discovered participation of 37 genes in 9 significantly over-represented pathways. Eight variants in these 37 genes have significantly higher frequency in young individuals, and are nominated for CHD association. Variants called only in the young individuals pool (13 variants) are also nominated for association with CHD. Based on sufficiently unambiguous literature data, from the nominated variants, we prioritize five as associated with CHD in the studied Bulgarian sample. Centenarian genomes can be used to provide additional information regarding the clinical relevance of genetic variants reported as associated with CHD.

Preimplantation genetic testing (PGT) is presently the only option available for detecting genetic conditions in embryos created through in vitro fertilization (IVF) prior to implantation. Thus PGT eliminates the dilemma of pregnancy termination following unfavorable prenatal diagnosis test results. Complex chromosome rearrangements (CCRs), although very rarely reported in humans, represent a significant clinical problem for their carriers. CCRs include at least three breakpoints affecting two or more chromosomes. In three-breakpoint translocations, theoretically sixty-four different chromosomal sets are produced. Only two of them will be balanced and will lead to the birth of a phenotypically normal child. Therefore, CCR carriers are at increased risk of chromosomally unbalanced conceptions, resulting in spontaneous abortions or birth of offspring with intellectual disability and/or congenital anomalies. The reproductive options before such families are: natural conception followed by prenatal diagnosis; donor gametes; adoption or PGT. In this paper we discuss the current state of the PGT field and report on two PGT-cases for CCR in families with infertility and recurrent pregnancy losses. The families underwent IVF-PGT on day 3 and day 5 embryos and whole genome microarray analysis.

Objectives: The aim of the present study was to evaluate the clinical relevance of mutations in tumor suppressor genes using whole-exome sequencing data from centenarians and young healthy individuals. Methods: Two pools, one of centenarians and one of young individuals, were constructed and whole-exome sequencing was performed. We examined the whole-exome sequencing data of Bulgarian individuals for carriership of tumor suppressor gene variants. Results: Of all variants annotated in both pools, 5080 (0.06%) are variants in tumor suppressor genes but only 46 show significant difference in allele frequencies between the two studied groups. Four variants (0.004%) are pathogenic/risk factors according to single nucleotide polymorphism database: rs1566734 in PTPRJ , rs861539 in XRCC3 , rs203462 in AKAP10 , and rs486907 in RNASEL . Discussion: Based on their high minor allele frequencies and presence in the centenarian group, we could reclassify them from pathogenic/risk factors to benign. Our study shows that centenarian exomes can be used for re-evaluating the clinically uncertain variants.

Mitochondrial DNA variants associated with diseases are widely studied in contemporary populations, but their prevalence has not yet been investigated in ancient populations. The publicly available AmtDB database contains 1443 ancient mtDNA Eurasian genomes from different periods. The objective of this study was to use this data to establish the presence of pathogenic mtDNA variants putatively associated with mitochondrial diseases in ancient populations. The clinical significance, pathogenicity prediction and contemporary frequency of mtDNA variants were determined using online platforms. The analyzed ancient mtDNAs contain six variants designated as being "confirmed pathogenic" in modern patients. The oldest of these, m.7510T>C in the MT-TS1 gene, was found in a sample from the Neolithic period, dated 5800-5400 BCE. All six have well established clinical association, and their pathogenic effect is corroborated by very low population frequencies in contemporary populations. Analysis of the geographic location of the ancient samples, contemporary epidemiological trends and probable haplogroup association indicate diverse spatiotemporal dynamics of these variants. The dynamics in the prevalence and distribution is conceivably result of de novo mutations or human migrations and subsequent evolutionary processes. In addition, ten variants designated as possibly or likely pathogenic were found, but the clinical effect of these is not yet well established and further research is warranted. All detected mutations putatively associated with mitochondrial disease in ancient mtDNA samples are in tRNA coding genes. Most of these mutations are in a mt-tRNA type (Model 2) that is characterized by loss of D-loop/T-loop interaction. Exposing pathogenic variants in ancient human populations expands our understanding of their origin and prevalence dynamics.

Early infantile epileptic encephalopathy (EIEE) is a disorder with variable genetic heterogeneity. Symptoms are mostly presented with generalised epileptic seizures with an infantile onset and progressive neurodevelopmental delay. Early infantile epileptic encephalopathy13 is caused by mutations in the SCN8A gene, which encodes the neuronal voltage-gated sodium channel α subunit (Nav1.6) and plays a major role in neuronal excitability. Describing the wide clinical variability of previously reported cases of patients carrying the same mutation, we demonstrate the complexity of the disease and the necessity of correctly correlating the phenotype with the genotype. Here, we present a minireview and a case report of EIEE13 involving the rare p.Arg1872Gln mutation in the SCN8A gene. We used targeted next-generation sequencing to examine a six-year-old girl with complex partial seizures from the left temporal lobe since 4 months of age. The condition was difficult to control with medication and the seizures evolved to generalised tonic-clonic seizures after the age of 3 years. Neurodevelopment in the child became severely delayed although seizures were as rare as 1 in every 5–10 months. А heterozygous missense mutation in the SCN8A gene (NM_014191.3:c.5616G > A, NP_055006.1:p.Arg1872Gln) was found. The variant was validated by Sanger sequencing. We suggest that this SCN8A mutation has a primary neurodegenerative effect leading to brain atrophy and intellectual disability (with or without autism) that is partially independent of its epileptogenic effect. Our results demonstrate that the application of large panels with clinically-associated genes is essential for identifying rare mutations in individuals with disorders of unknown etiology.

An ever larger portion of the world population survives into advanced old age, and that has been a steady trend for the last century. Despite some substantial advances in our understanding of the genomic basis of ageing in recent years, healthy ageing remains an increasingly important social task. Initially established in model organisms, many human orthologue genes and pathways associated with longevity have been identified. Ageing is a result from the declining ability of the human organism to maintain homeostatic balance and to regenerate damaged cells and tissues, and is the main risk factor for the prevalent diseases in developed countries. It could be imagined that the genome of very old individuals is purged of disease-causing variants, but recent studies have demonstrated that long-lived individuals carry the same number of disease alleles as young controls. Longevity may however also be explained by the presence of protective genetic factors against age-related phenotypes and diseases, and there is a pertinent need for these to be identified. Centenarians are the extreme phenotype of human longevity and their genomes undoubtedly contain clues about genes and pathways that are involved in longevity. Understanding the genomic basis of ageing, together with knowledge of population ecology and insights from evolutionary biology, will shed light on the biological mechanisms underlying human longevity and hence on the potential of extending healthy human life span.

Cardiovascular diseases (CVD) comprise a broad range of disorders of the heart and blood vessels. In this study, we used next-generation sequencing with a panel that includes 174 genes connected to CVD in order to investigate the possible genetic causes that underline some clinical phenotypes and their severity. Two patients were found with double heterozygosity, each carrying one new variant. One patient with supravalvular aortic stenosis has novel ELN: c.890-1G>A and a known variant SCN5A: p.Gly9Val in a heterozygous state, whereas another patient with hypertrophic cardiomyopathy has a heterozygous novel CACNA1C: p.Arg514Gly and a known SCN5A: p.Arg800His variant. This method proved to be useful in determining the mutation status in correlation with the severity of the clinical phenotype and can further clarify cases where the clinical status could not be explained only by single gene mutation detected by standard methods.

We report the unique case of a 61-year-old male patient with known pancreatic incidentaloma who additionally developed 3 other histologically different tumors: left sphenoid wing meningothelial meningioma, basal cell carcinoma of the occiput, and right occipital lobe glioblastoma multiforme. The latter were totally removed with a favorable clinical outcome. The patient’s family history was unremarkable, and no data on any previous head and neck irradiation were found.

Thyroid cancer is the most common malignant tumour of the endocrine system. One of the most frequent types of thyroid malignancy is papillary carcinoma. In our study, we performed next generation sequencing (NGS) using a cancer panel (Illumina; Illumina, San Diego, USA) to screen for pharmacogenetic susceptibility variants in blood samples of 10 patients with papillary thyroid cancer (PTC). We report variants rs1042522 (TP53), rs2228001 (XPC), rs2227983 (EGFR), rs13181 (ERCC2), rs17655 (ERCC5) and rs1799939 (RET), which were detected in the analyzed patients either in homozygous and/or heterozygous state previously known to be connected with pharmacogenetic sensitivity to certain drugs in oncology. The results showed the TruSight Cancer Panel to be a useful clinical tool for determination of oncotherapy-associated pharmacogenetic variants in the blood of patients.

BACKGROUND:The GGGGCC repeat expansion in the C9orf72 gene was recently identified as a major cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) in several European populations. The objective of this study was to determine the frequency of C9orf72 repeat expansions in a Bulgarian dementia cohort and to delineate the associated clinical features. METHODS AND FINDINGS:PCR-based assessments of the C9orf72 hexanucleotide repeat expansion in all study samples (including 82 FTD, 37 Alzheimer's disease (AD), and 16 other neurodegenerative/dementia disorder cases) were performed. We report the clinical, neuropsychological, and neuroimaging findings obtained for the C9orf72 repeat expansion carriers. Of the 135 cases screened, 3/82 (3.7%) of all FTD cases and 1/37 (2.7%) of all clinical AD cases had a C9orf72 repeat expansion. In this cohort, the C9orf72 pathological expansion was found in clinical diagnoses bridging the FTD, parkinsonism, ALS and AD spectrum. Interestingly, we showed early writing errors without aphasia in two subjects with C9orf72 expansions. CONCLUSIONS:This study represents the first genetic screening for C9orf72 repeat expansions in a Bulgarian dementia cohort. The C9orf72 repeat expansion does not appear to be a common cause of FTD and related disorders. This report confirms the notion that C9orf72 repeat expansions underlie a broad spectrum of neurodegenerative phenotypes. Relatively isolated agraphia in two cases with C9orf72 repeat expansions is a strong motivation to provide detailed and sophisticated oral and written language assessments that can be used to more precisely characterize early cognitive deficits in these heterogeneous conditions.

Interstitial microdeletions of the distal 2p are very rare. A small number of cases have been reported in the literature, involving regions 2p23-p25, 2p23-p24 and 2p24-p25. The most common symptoms involve: intrauterine growth retardation, developmental delay, mental retardation, microcephaly, craniofacial anomalies, musculoskeletal abnormalities, congenital heart defect and hearing impairment. Herein we report on a Caucasian girl, born after in vitro fertilization with discrete facial dysmorphism, growth failure, borderline neurodevelopment and congenital heart defect. A de novo pericentric inversion of chromosome 2 was identified by routine karyotyping. An interstitial microdeletion of 2p24.3p25.1 was found by array karyotyping and following FISH analysis revealed that the deletion affects the inverted chromosome 2. This case illustrates the utility of high resolution methods to identify submicroscopic quantitative changes in structurally rearranged chromosomes. The precise determination of the genetic content of small quantitative changes in the genome provides important information for genetic counseling, enabling to predict the course of disease and the planning of adequate therapy and prophylaxis in affected families.

Congenital anomalies affect 1% to 2% of the newborns. The urinary tract and the kidneys are involved in 4-5% of the cases while upper-extremities abnormalities are present in 10%. Certain anomalies occur in isolation, whereas others are associated with systemic conditions. The prenatal detection of fetal anomalies compatible with life is a challenge for both the parents and the physician. The prognosis for the fetus/newborn and the reproductive decisions of the family largely depend on the causes underlying the disease. The reported case is of a G2P1 pregnant woman referred for routine ultrasound scan at 24 weeks of gestation (w.g.). The fetus had growth retardation, right kidney agenesis, bilateral absence of radial bones and thumbs, radial deviation of the wrists, and short humeri. Nuchal fold thickness was 5 mm and there was a single umbilical artery. After termination of pregnancy, SNP array genotyping and next-generation sequencing of targeted candidate-genes were performed trying to clarify the etiology of the fetal polymalformative syndrome. A new hypomorphic mutation in FANCD2 gene was found to underlie this fetal anomaly. The case illustrates that patients/families affected by rare monogenic disorders may benefit from application of modern technologies like microarrays and NGS.

1H NMR spectroscopy of urine has been applied to exploring metabolomic differences between people diagnosed with Balkan endemic nephropathy (BEN), and treated by haemodialysis, and those without overt renal disease in Romania and Bulgaria. Convenience sampling was made from patients receiving haemodialysis in hospital and healthy controls in their village. Principal component analysis clustered healthy controls from both countries together. Bulgarian BEN patients clustered separately from controls, though in the same space. However, Romanian BEN patients not only also clustered away from controls but also clustered separately from the BEN patients in Bulgaria. Notably, the urinary metabolomic data of two people sampled as Romanian controls clustered within the Romanian BEN group. One of these had been suspected of incipient symptoms of BEN at the time of selection as a ‘healthy’ control. This implies, at first sight, that metabolomic analysis can be predictive of impending morbidity before conventional criteria can diagnose BEN. Separate clustering of BEN patients from Romania and Bulgaria could indicate difference in aetiology of this particular silent renal atrophy in different geographic foci across the Balkans.

OBJECTIVE: The majority of adults diagnosed with acute myeloid leukemia (AML) display acquired cytogenetic aberrations at presentation. In this article, we present the major cytogenetic findings regarding AML and review their clinical significance for achievement of the first complete remission.METHODS: We studied 71 adult patients with de novo AML, without previous myelodysplasia or alkylating therapy. Conventional cytogenetics and FISH were performed on bone marrow cells. The patients with AML were assigned to 12 subgroups according to established data for cytogenetic, molecular and general laboratory results. The selection of the analyzed parameters is consistent with internationally accepted “prognostic factors” in adult AML.RESULTS: Complete remission upon induction therapy was achieved in 40% of cases (in a mean period of 2.3 months from therapy initiation). The patients with t(15;17) PML-RARA and inv(16)/CBFbeta-MYH11ë demonstrated the highest frequency of complete remission. Patients with hypodiploidy, t(9;22)/bcr-abl and complex karyotypes were therapy-resistant or died within the first three months after AML diagnosis. CONCLUSION: Molecular-cytogenetic findings have an important significance for achievement of first complete remission. However, laboratory and biologic features (age, WBC and LDH) and type of AML have a large influence on the disease outcome.

To better define the structure and origin of the Bulgarian paternal gene pool, we have examined the Y-chromosome variation in 808 Bulgarian males. The analysis was performed by high-resolution genotyping of biallelic markers and by analyzing the STR variation within the most informative haplogroups. We found that the Y-chromosome gene pool in modern Bulgarians is primarily represented by Western Eurasian haplogroups with ∼ 40% belonging to haplogroups E-V13 and I-M423, and 20% to R-M17. Haplogroups common in the Middle East (J and G) and in South Western Asia (R-L23*) occur at frequencies of 19% and 5%, respectively. Haplogroups C, N and Q, distinctive for Altaic and Central Asian Turkic-speaking populations, occur at the negligible frequency of only 1.5%. Principal Component analyses group Bulgarians with European populations, apart from Central Asian Turkic-speaking groups and South Western Asia populations. Within the country, the genetic variation is structured in Western, Central and Eastern Bulgaria indicating that the Balkan Mountains have been permeable to human movements. The lineage analysis provided the following interesting results: (i) R-L23* is present in Eastern Bulgaria since the post glacial period; (ii) haplogroup E-V13 has a Mesolithic age in Bulgaria from where it expanded after the arrival of farming; (iii) haplogroup J-M241 probably reflects the Neolithic westward expansion of farmers from the earliest sites along the Black Sea. On the whole, in light of the most recent historical studies, which indicate a substantial proto-Bulgarian input to the contemporary Bulgarian people, our data suggest that a common paternal ancestry between the proto-Bulgarians and the Altaic and Central Asian Turkic-speaking populations either did not exist or was negligible.

Using principal component (PC) analysis, we studied the genetic constitution of 3,112 individuals from Europe as portrayed by more than 270,000 single nucleotide polymorphisms (SNPs) genotyped with the Illumina Infinium platform. In cohorts where the sample size was >100, one hundred randomly chosen samples were used for analysis to minimize the sample size effect, resulting in a total of 1,564 samples. This analysis revealed that the genetic structure of the European population correlates closely with geography. The first two PCs highlight the genetic diversity corresponding to the northwest to southeast gradient and position the populations according to their approximate geographic origin. The resulting genetic map forms a triangular structure with a) Finland, b) the Baltic region, Poland and Western Russia, and c) Italy as its vertexes, and with d) Central- and Western Europe in its centre. Inter- and intra- population genetic differences were quantified by the inflation factor lambda (lambda) (ranging from 1.00 to 4.21), fixation index (F(st)) (ranging from 0.000 to 0.023), and by the number of markers exhibiting significant allele frequency differences in pair-wise population comparisons. The estimated lambda was used to assess the real diminishing impact to association statistics when two distinct populations are merged directly in an analysis. When the PC analysis was confined to the 1,019 Estonian individuals (0.1% of the Estonian population), a fine structure emerged that correlated with the geography of individual counties. With at least two cohorts available from several countries, genetic substructures were investigated in Czech, Finnish, German, Estonian and Italian populations. Together with previously published data, our results allow the creation of a comprehensive European genetic map that will greatly facilitate inter-population genetic studies including genome wide association studies (GWAS).