Iglika Sotkova-Ivanova

Background/Objectives: Pharmacogenetic variability influences the efficacy and toxicity of anticancer therapies. However, Eastern European populations remain underrepresented in pharmacogenetic databases. This study aimed to characterize pharmacogenetic variants relevant to chemotherapy response in the Bulgarian population and compare their allele frequencies with reference populations. Methods: Ninety individuals were included, comprising 50 patients with colorectal, non-small cell lung, or breast cancer and 40 healthy controls. Genomic DNA and circulating cell-free DNA were analyzed by next-generation sequencing targeting pharmacogenetic genes involved in drug metabolism, transport, and DNA repair. Allele frequencies were compared with gnomAD v2.1.1 reference data. Sensitivity analyses compared Bulgarian controls with Bulgarian non-cancer and combined Southern European, Northwestern European, and Other non-Finnish European non-cancer populations. Results: Twenty-three pharmacogenetic variants were evaluated. Six variants remained statistically significant after Benjamini–Hochberg correction in both Fisher’s exact test and the two-proportion Z-test. Five variants—DPYD c.2194G>A, XPC c.2815C>A, EGFR c.1562G>A, XRCC1 c.1196A>G, and ERCC2 c.2251A>C—showed higher allele frequencies, whereas ERCC2 c.934G>A was less frequent in the Bulgarian cohort. DPYD c.85T>C remained significant after correction in the Z-test but not in Fisher’s exact test. Sensitivity analyses confirmed the significance of XPC c.2815C>A in both reference-population comparisons, while DPYD c.85T>C remained significant only against the combined European reference population. Conclusions: Several pharmacogenetic variants showed distinct allele frequencies in the Bulgarian cohort. XPC c.2815C>A demonstrated the most robust population-specific pattern across sensitivity analyses. These findings highlight the value of locally derived pharmacogenetic data for precision oncology and pharmacogenetically guided treatment strategies.

Clonal hematopoiesis of indeterminate potential (CHIP) is an age-associated premalignant state defined by somatic mutations in hematopoietic cells at a variant allele frequency (VAF) ≥2% in the absence of overt hematologic malignancy. Among CHIP-associated mutations, JAK2 V617F is of particular interest because it occupies a dual biological and clinical role: it is both the principal driver of BCR::ABL1-negative myeloproliferative neoplasms (MPNs) and a clonal hematopoiesis variant conferring approximately 12-fold cardiovascular risk in selected cohorts, exceeding that reported for common DTA CHIP variants. Quantitative assessment of JAK2 V617F allele burden is therefore clinically relevant across the full disease continuum—from subclinical clonal expansion to MPN diagnosis, prognostic stratification, and therapeutic monitoring—as VAF thresholds correlate with disease phenotype, thrombotic risk, molecular response, and fibrotic progression. Digital PCR platforms, including droplet digital PCR (ddPCR) and chip-based digital PCR, have emerged as highly sensitive and reproducible methods for absolute JAK2 V617F quantification without the need for standard curves, with reported limits of detection as low as 0.01%. In this review, we synthesize current evidence on the molecular biology of JAK2-driven clonal hematopoiesis, the clinical significance of allele burden quantification, and the analytical performance of digital PCR compared with quantitative PCR and next-generation sequencing. We interpret these findings through a systems biology lens that draws together JAK-STAT signaling networks and thrombo-inflammatory pathways including inflammasome-dependent IL-1 signaling, clonal architecture, and bone marrow microenvironmental remodeling. We also discuss published quantitative models in which JAK2 V617F allele burden is treated as a dynamic state variable, while emphasizing that the present review offers a conceptual synthesis rather than a new computational model. We provide a structured comparative synthesis of published digital PCR analytical performance data, a stage-adapted proposal for clinical monitoring, and schematic models to guide future implementation. Overall, the evidence supports digital PCR as a precision tool for monitoring JAK2 V617F clonal dynamics across the CHIP–MPN spectrum, and points to several priorities: assay standardization, harmonized reporting, external quality assessment, and prospective clinical validation.

Background/Objectives: Pharmacogenetic variability plays an important role in determining the efficacy and toxicity of anticancer therapies. However, Eastern European populations remain underrepresented in global pharmacogenetic databases, limiting the implementation of population-specific precision medicine approaches. This study aimed to characterize pharmacogenetic variants relevant to chemotherapy response in the Bulgarian population and compare their allele frequencies with those reported in global populations. Methods: A total of 90 individuals were included, comprising 50 patients diagnosed with colorectal, non-small cell lung, or breast cancer and 40 healthy controls. Genomic DNA and circulating cell-free DNA samples were analyzed using next-generation sequencing targeting clinically relevant pharmacogenetic genes involved in drug metabolism, transport, and DNA repair. Allele frequencies were determined and compared with available global population data. Results: Twenty-three pharmacogenetic variants were evaluated. Six variants, namely MTHFR c.665C>T, DPYD c.2194G>A, XPC c.2815C>A, EGFR c.1562G>A, XRCC1 c.1196A>G, and ERCC2 c.2251A>C, exhibited significantly higher allele frequencies in the Bulgarian cohort than in global populations (p < 0.05). In contrast, four variants, MTHFR c.1286A>C, DPYD c.85T>C, ABCG2 c.421C>A, and ERCC2 c.934G>A, were significantly less frequent (p < 0.05). Conclusions: The Bulgarian population exhibits distinct pharmacogenetic characteristics compared with global reference populations. These findings contribute to the understanding of population-specific genetic variability and support the incorporation of Bulgarian pharmacogenetic data into precision oncology research and pharmacogenetic-guided treatment strategies.

Background: The use of low-molecular-weight heparins (LMWH) for the treatment and prevention of thromboembolic diseases in pediatric patients is increasing, although optimal dosing and monitoring strategies remain insufficiently defined. Methods: This study was conducted at the Clinic of Pediatrics, University Hospital “St. George”, and included 26 hospitalized patients aged 0–18 years with confirmed arterial or venous thrombosis receiving treatment or prophylaxis with enoxaparin. A total of 42 samples were analyzed. Anti-factor Xa activity was measured using an LMWH-calibrated anti-FXa assay (Innovance Heparin, Siemens Healthineers) on a Sysmex CS-2500 analyzer. Therapeutic and prophylactic dosing followed CHEST 2012 guidelines. The study evaluated age- and weight-based dosing, the number of dose adjustments required to achieve target Anti-Xa levels, and the relationship between Anti-Xa levels and anticoagulant response. Results: The mean baseline Anti-Xa level achieved with the initial weight-based dose (1.0 mg/kg/12 h) was significantly lower in children aged 1–2 years compared with older age groups. Older children, as well as patients with oncological and nephrological diseases, achieved higher anticoagulant levels with standard prophylactic dosing. Age under 1 year, oncological disease, and baseline Anti-Xa level < 0.3 IU/mL were identified as independent predictors of the need for more frequent dose adjustments to achieve a therapeutic response. Conclusions: Monitoring of Anti-factor Xa levels is essential in pediatric patients receiving LMWH for both treatment and prophylaxis. Standard dosing regimens may be insufficient in younger children and specific clinical subgroups, supporting the need for individualized dosing strategies.

The comorbidity of autistic spectrum disorder (ASD) and epilepsy has been widely discussed but many questions still remain unanswered. The aim of this study was to establish the occurrence of epilepsy among children with ASD to define the type of epileptic seizures and syndromes, the age of onset of epilepsy, EEG abnormalities, the used antiepileptic drugs and the therapeutic responses for seizures and autistic behavior, as well as to find some correlations between epilepsy and gender, etiology and intellectual disability (ID). A retrospective study of medical files of 59 patients (aged 1–18 years) with ASD during a 5-year period was performed. ASD diagnosis was based on the DSM-5 diagnostic criteria. The patients were examined with a detailed medical history, physical and neurological examination, as well as some additional functional, imaging, laboratory and genetic investigations ASD etiology was syndromic in 9, probable syndromic in 9, and idiopathic in 41 children. ID was established in 90% of ASD children, and epilepsy in 44.4%. The onset of epilepsy prevailed before 7 years of age. The most common seizure types were focal with or without secondary generalization (53.4%). Focal epileptiform EEG abnormalities prevailed. Therapeutic response to seizures was good: 58% were seizure-free, while 27% had >50% seizure reduction but no improvement in autistic behavior. There was no correlation between epilepsy and either occurrence or degree of ID. There was a correlation between the frequency of epileptic seizures and the degree of ID. There was no significant difference among epilepsy rates in different etiologic, gender, and ID groups, probably because of the high percentage of ID and because this was a hospital-based study. Our study showed a significant percentage of epilepsy in ASD population and more than 1/4 were of symptomatic etiology. Those could be managed with specific treatments based on the pathophysiology of the gene defect.