Multidisciplinary, Biochemistry, Genetics and Molecular Biology, Aging, Genetics
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Scopus Publications
Scopus Publications
Complete mtDNA sequencing reveals mutations m.9185T>C and m.13513G>A in three patients with Leigh syndrome Dita Pelnena, Birute Burnyte, Eriks Jankevics, Baiba Lace, Evelina Dagyte, et al. Mitochondrial DNA Part A DNA Mapping Sequencing and Analysis, 2018 The most common mitochondrial disorder in children is Leigh syndrome, which is a progressive and genetically heterogeneous neurodegenerative disorder caused by mutations in nuclear genes or mitochondrial DNA (mtDNA). In the present study, a novel and robust method of complete mtDNA sequencing, which allows amplification of the whole mitochondrial genome, was tested. Complete mtDNA sequencing was performed in a cohort of patients with suspected mitochondrial mutations. Patients from Latvia and Lithuania (n = 92 and n = 57, respectively) referred by clinical geneticists were included. The de novo point mutations m.9185T>C and m.13513G>A, respectively, were detected in two patients with lactic acidosis and neurodegenerative lesions. In one patient with neurodegenerative lesions, the mutation m.9185T>C was identified. These mutations are associated with Leigh syndrome. The present data suggest that full-length mtDNA sequencing is recommended as a supplement to nuclear gene testing and enzymatic assays to enhance mitochondrial disease diagnostics.
Population Genetics of Latvians in the Context of Admixture between North-Eastern European Ethnic Groups Astrīda Krūmiņa, Liāna Pliss, Gunita Zariņa, Agrita Puzuka, Agnese Zariņa, et al. Proceedings of the Latvian Academy of Sciences Section B Natural Exact and Applied Sciences, 2018 This article presents a review on population genetics of Latvians, which alongside Lithuanians are the two extant Baltic speaking populations. The article provides a description of genome-wide single nucleotide polymorphism (SNP) data and contains a comparative analysis of the results of studies performed on classical autosomal genetic markers, mitochondrial DNA (mtDNA) and the non-recombining part of the Y chromosome (NRY), with data on neighbouring populations. The study also covers data of recently performed ancient DNA (aDNA) studies carried out on samples from the territory of today’s Latvia. The results of population genetic studies have shown a mixture of eastern and western genetic traits in present-day Latvians with only small differences between Latvian subpopulations. Studies of the Baltic “tribal gene” LW b , as well as the gene’s SERPINA1 allele PIZ have indicated the presence of a considerable Baltic admixture in the neighbouring Finno-Ugric and Slavic populations. Although mtDNA analyses have shown that Latvians genetically in general belong to the same common gene pool as most of the Europeans, the Y-chromosomal lineage composition suggests that they are most similar to Northern and Eastern European populations of Lithuanians, Estonians, and Eastern-Slavic populations, which are ethnogenetically closest to them. The analysis of aDNA from the Early and Middle Neolithic did not present any genomic evidence of gene-flow from Central European farmers or any mitochondrial or Y-chromosomal haplogroups that are typical for them in the hunter-gatherers from the territory of today’s Latvia and Lithuania.
Linkage between mitochondrial genome alterations, telomere length and aging population Egija Zole, Krista Zadinane, Liana Pliss, Renate Ranka Mitochondrial DNA Part A DNA Mapping Sequencing and Analysis, 2018 We studied telomere length (TL) and mitochondrial DNA (mtDNA) copy number variations in individuals from Latvian Caucasian population in different age groups. We showed a positive correlation between TL and mtDNA copy number in individuals of up to 90 years of age; however, this correlation was not observed in the 90–100 years age group. While TL shortened with age and mtDNA content decreased with increasing age, in this study it was observed that mtDNA copy number in nonagenarians was slightly higher than in the 60–89 years age group. The presence of heteroplasmy in the mtDNA HVS-I control region did not correlate with TL and mtDNA copy number. TL and mtDNA values also did not differ between mitochondrial haplogroups. In conclusion, while both TL and mtDNA are involved in the aging process and link between these cell components exists, nonagenarians may have differences in senescence-related pathways and systems, which may function as a protective mechanism that allows them to live longer.
Y-Chromosomal Lineages of Latvians in the Context of the Genetic Variation of the Eastern-Baltic Region Liana Pliss, Līga Timša, Siiri Rootsi, Kristiina Tambets, Inese Pelnena, et al. Annals of Human Genetics, 2015 SummaryVariations of the nonrecombining Y‐chromosomal region were investigated in 159 unrelated Baltic‐speaking ethnic Latvians from four different geographic regions, using 28 biallelic markers and 12 short tandem repeats. Eleven different haplogroups (hgs) were detected in a regionally homogeneous Latvian population, among which N1c, R1a, and I1 cover more than 85% of its paternal lineages. When compared its closest geographic neighbors, the composition of the Latvian Y‐chromosomal gene pool was found to be very similar to those of Lithuanians and Estonians. Despite the comparable frequency distribution of hg N1c in Latvians and Lithuanians with the Finno‐Ugric‐speaking populations from the Eastern coast of the Baltic Sea, the observed differences in allelic variances of N1c haplotypes between these two groups are in concordance with the previously stated hypothesis of different dispersal ways of this lineage in the region. More than a third of Latvian paternal lineages belong specifically to a recently defined R1a‐M558 hg, indicating an influence from a common source within Eastern Slavic populations on the formation of the present‐day Latvian Y‐chromosome gene pool.
Morphological characterisation and molecular sex determination of human remains from the 15th-17th centuries in Latvia Asta Ščėsnaitė-Jerdiakova, Liāna Pliss, Guntis Gerhards, Elīna Pētersone Gordina, Agnija Gustiņa, et al. Proceedings of the Latvian Academy of Sciences Section B Natural Exact and Applied Sciences, 2015 Sex determination is one of the most important and initial steps in human profile identification from archaeological material. The aim of the current study was to evaluate the application of molecular approaches alongside morphological methods for sex determination in archaeological human skeletal remains. Human skeletal remains were excavated from three cemeteries: St Gertrude Old Church, Dom Square and St Peter’s Church, of 15th–17th century burials in Rīga, Latvia. Morphological and molecular genetic methods, including amplification of genes AMELX/Y and SRY were used to analyse seven skeletal remains. The conducted analyses of morphological features identified sex in all seven cases (two females and five males). By molecular analyses of mediaeval DNA it was possible to determine sex in five of seven (71%) samples. In all positive cases full agreement between morphological estimation and molecular genetic methods was observed. To conclude, DNA analysis can be considered for sex identification in cases with no signs of sexual dimorphism (juvenile skeletons) or partially preserved skeletons.
Point mutations associated with Leber hereditary optic neuropathy in a Latvian population Molecular Vision, 2013
Dynamics of telomere length in different age groups in a Latvian population. Egija Zole, Liana Pliss, Renate Ranka, Astrida Krumina, Viesturs Baumanis Current Aging Science, 2013 The shortening of telomeres with ageing is a well-documented observation; however, the reported number of nucleotides in telomeres varies between different laboratories and studies. Such variability is likely caused by ethnic differences between the populations studied. Until now, there were no studies that investigated the variability of telomere length in a senescent Latvian population of the most common mitochondrial haplogroups, defined as H (45%), U (25%), Y chromosomal N1c (40%) and R1a1 (40%). Telomere length was determined in 121 individuals in different age groups, including a control group containing individuals of 20-40 years old and groups of individuals between 60-70 years old, 71-80 years old, 81-90 years old, and above 90 years old. Telomere length was determined using the Southern blot telomeric restriction fragment assay (TRF). Decreased telomere length with ageing was confirmed, but a comparison of centenarians and individuals between 60-90 years of age did not demonstrate a significant difference in telomere length. However, significant variability in telomere length was observed in the control group, indicating probable rapid telomere shortening in some individuals that could lead up to development of health status decline appearing with ageing. Telomere length measured in mononuclear blood cells (MNC) was compared with the telomere length measured in whole peripheral white blood cells (WBC) using TRF. Telomere length in MNC was longer than in WBC for the control group with individuals 20 to 40 years old; in contrast, for the group of individuals aged 65 to 85 years old, measured telomere length was shorter in MNC when compared to WBC.
Association studies of candidate genes and cleft lip and palate taking into consideration geographical origin Baiba Lace, Inga Kempa, Linda Piekuse, Ieva Grinfelde, Janis Klovins, et al. European Journal of Oral Sciences, 2011 Isolated cleft lip and/or palate (CL/CLP) is a complex congenital anomaly with many contributing factors. There are several genes involved in the aetiology of CL/CLP, they are different in selected populations. In a previous study, the mitochondrial haplotypes of Latvian subjects with CL/CLP were characterized. Latvian subjects with CL/CLP have mostly mitochondrial haplogroups U4/U5 compared with the ethnic population of Latvia. The aim of this study was to stratify the results of genotyping based on European mitochondrial DNA (mtDNA) haplotypes. DNA samples from 108 patients with CL/CLP and from 182 unrelated and unaffected individuals selected randomly in Latvia (used as controls) were obtained for investigation. In this study, we analysed the data taking into consideration mitochondrial haplogroups and found that gene associations depended on the genetic origin of the population. The phenotype of patients with non-U haplotypes was associated with markers in wingless-type MMTV integration site family, member 3 (WNT3), collagen, type XI, alpha 2 (COL11A2), and fibroblast growth factor receptor 1 (FGFR1), whereas patients with U4 and U5 haplotypes showed significant association with WNT3 and COL11A2. It is unlikely that mtDNA variants play a direct role in the development of CL/CLP; rather, they may be a surrogate for population substructure and provide a tool to increase homogeneity and statistical power.
