Gilbert syndrome (GS) is characterized by unconjugated hyperbilirubinemia without liver disease or overt hemolysis and it is found in 3-10% of the general population. Inherited hyperbilirubinaemia is attributable to a reduced UGT1A1 activity. The UGT1A1 promoter (TA) repeats variants are documented of being involved in abnormally elevated bilirubin levels. The aim of the present study is to analyze the impact of UGT1A1 promoter variants on bilirubin levels in Romanian patients clinically supected with GS. The study group included 897 subjects: 292 GS patients and 605 healthy controls. Genomic DNA was extracted from the peripheral blood leukocytes. All individuals were screened for the presence of the (TA) insertion in the TATA box region of UGT1A1 gene by PCR amplification. This case-control study was conducted at the Department of Medical Genetics, Synevo, Romania. UGT1A1*28 (7TA) revealed the highest frequency (61.87%) of all individuals, while the UGT1A1*1 (6TA) allele was found in 36.79%. We identified two other variants of the UGT1A1 gene, depending on the number of TA repeats in the promoter: 5TA (0.61%) and 8TA (0.72%). The (TA)7/7 homozygous genotype was identified in 32.33% of all individuals, while the (TA)6/7 heterozygous genotype was the most prevalent (57.64%). The wild type (TA)6/6 was identified in 7.36% of the whole cohort. Because other polymorphisms have been associated with GS, the absence of the UGT1A1*28 allele does not rule out this condition. The results suggest that in the Romanian population there is a strong correlation between the UGT1A1*28 polymorphism and hyperbilirubinemia in patients with GS.

The HLA genes are associated with various autoimmune pathologies, with the control of the immune response also being significant in organs and cells transplantation. The aim of the study is to identify the HLA-A, HLA-B, and HLA-C alleles frequencies in the analyzed Romanian cohort. We performed HLA typing using next-generation sequencing (NGS) in a Romanian cohort to estimate class I HLA allele frequencies up to a six-digit resolution. A total of 420 voluntary donors from the National Registry of Voluntary Hematopoietic Stem Cell Donors (RNDVCSH) were included in the study for HLA genotyping. Peripheral blood samples were taken and brought to the Fundeni Clinical Institute during 2020–2021. HLA genotyping was performed using the Immucor Mia Fora NGS MFlex kit. A total of 109 different alleles were detected in 420 analyzed samples, out of which 31 were for HLA-A, 49 for HLA-B, and 29 for HLA-C. The most frequent HLA-A alleles were HLA-A*02:01:01 (26.11%), HLA-A*01:01:01 (12.5%), HLA-A*24:02:01 (11.67%), HLA-A*03:01:01 (9.72%), HLA-A*11:01:01, and HLA-A*32:01:01 (each with 8.6%). For the HLA-B locus, the most frequent allele was HLA-B*18:01:01 (11.25%), followed by HLA-B*51:01:01 (10.83%) and HLA-B*08:01:01 (7.78%). The most common HLA-C alleles were HLA-C*07:01:01 (17.36%), HLA-C*04:01:01 (13.47%), and HLA-C*12:03:01 (10.69%). Follow-up studies are ongoing for confirming the detected results.

Next-generation sequencing (NGS) has completely revolutionized the analysis of HLA genes, offering superior resolution and the possibility of identifying previously unknown or rare alleles. NGS technology allows for the complete sequencing of the the HLA locus, the analysis of coding and non-coding regions, and a detailed characterization of haplotypes, with essential benefits in areas such as organ transplantation and in studies of autoimmune diseases. The chapter explores the applications of NGS in personalized medicine, including the identification of neoantigens for oncology immunotherapies and the development of vaccines adapted to the genetic diversity of the population. Bioinformatic and ethical challenges are also discussed. By reducing the limitations of traditional methods and opening up new horizons for research and clinical applications, NGS is redefining the standards in HLA typing and is making a significant contribution to the progress of precision medicine.

HLA (Human Leukocyte Antigen) genes are a cornerstone of immunogenetics, having a significant impact on a wide range of biological processes and pathologies, from immune responses to the evolution of autoimmune and infectious diseases. Modern sequencing technologies, such as Next-Generation Sequencing (NGS), allow for detailed analysis of this complex system, providing unprecedented resolution. By integrating these advanced technologies, research in the HLA field opens new opportunities for personalized medicine, enabling early diagnosis, treatment of autoimmune diseases, transplantation, and immunotherapy. Furthermore, HLA sequencing plays a crucial role in vaccine development and innovative treatments, contributing to public health improvement and patient quality of life. In addition to its medical impact, HLA also plays an important role in anthropology, providing essential insights into human genetic diversity, population evolution, and adaptation to the environment, as well as interactions with pathogens. HLA studies help reconstruct human history by identifying migration routes and evolutionary mechanisms. To fully leverage the potential of HLA in research and clinical practice, bioinformatics and artificial intelligence methods are essential, enabling rapid analysis and interpretation of complex data. Technological advancements continue to transform the field, facilitating the development of new therapeutic strategies and high-precision diagnostics.