Genetic Basis of Early Onset Atrial Fibrillation in Patients without Risk Factors

Funding Information: This research was funded by the Latvian Council of Science, project, “The role of clonal hemato-poiesis of indeterminate potential as a potential driver of cardiovascular diseases and its associ-ation with clinical outcome”, project No. lzp-2021/1-0293. Publisher Copyright: © 2023 by the authors.Background: Atrial fibrillation (AF) is the most common arrhythmia and typically occurs in elderly patients with other cardiovascular and extracardiac diseases. However, up to 15% of AF develops without any related risk factors. Recently, the role of genetic factors has been highlighted in this particular form of AF. Aims: The aims of this study were to determine the prevalence of pathogenic variants in early-onset AF in patients without known disease-related risk factors and to identify any structural cardiac abnormalities in these patients. Materials and Methods: We conducted exome sequencing and interpretation in 54 risk factor-free early-onset AF patients and further validated our findings in a similar AF patient cohort from the UK Biobank. Results: Pathogenic/likely pathogenic variants were found in 13/54 (24%) patients. The variants were identified in cardiomyopathy-related and not arrhythmia-related genes. The majority of the identified variants were TTN gene truncating variants (TTNtvs) (9/13 (69%) patients). We also observed two TTNtvs founder variants in the analysed population—c.13696C>T p.(Gln4566Ter) and c.82240C>T p.(Arg27414Ter). Pathogenic/likely pathogenic variants were found in 9/107 (8%) individuals from an independent similar AF patient cohort from the UK Biobank. In correspondence with our Latvian patients, only variants in cardiomyopathy-associated genes were identified. In five (38%) of the thirteen Latvian patients with pathogenic/likely pathogenic variants, dilation of one or both ventricles was identified on a follow-up cardiac magnetic resonance scan. Conclusions: We observed a high prevalence of pathogenic/likely pathogenic variants in cardiomyopathy-associated genes in patients with risk factor-free early-onset AF. Moreover, our follow-up imaging data indicate that these types of patients are at risk of developing ventricular dilation. Furthermore, we identified two TTNtvs founder variants in our Latvian study population.publishersversionPeer reviewe

GJB1 Gene Analysis in Two Extended Families with X-Linked Charcot-Marie-Tooth Disease

Funding Information: The study was carried out using the internal research grant in Riga Stradins University. Publisher Copyright: © 2021 The Author(s). Published by S. Karger AG, Basel.X-linked Charcot-Marie-Tooth (CMT) disease type I (CMTX1) is the second most frequent type of CMT disease caused by pathogenic variants in the GJB1 gene. We described 2 extended cases (families) with CMTX1 with identified pathogenic variants - p.Val139Met and p.Arg215Trp. In both the families, neurological symptoms started earlier in male than in female patients. In some family members, molecular diagnostics was performed prior to neurological investigation due to family cascade screening. There was variable neurological phenotype representing CMT. Conclusions: There is a large clinical heterogeneity in CMTX, even amongst the family members.publishersversionPeer reviewe

New-Born Screening for Spinal Muscular Atrophy : Results of a Latvian Pilot Study

Funding Information: Funding: This research was funded by Latvian Science Council project No 2020/2-0275. Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.New disease-modifying treatments have recently been approved for 5q spinal muscular atrophy (SMA) and early treatment has been associated with a better clinical outcome. Accordingly, new-born screening (NBS) for SMA should be implemented to ensure early diagnosis of affected individuals. The aim of this study was to determine the feasibility and usefulness of NBS for SMA in Latvia. Between February and November of 2021, 10,411 parents consented to participation in the study. DNA testing for the SMN1 exon 7 homozygous deletion was conducted using qPCR with fluorescent locked nucleic acid primers. In the first month of testing, reporting of results took up to a maximum of 17 days after samples arrived in the laboratory. However, following familiarisation with the procedure, the median report time was reduced to 11 days after birth. Forty cases required samples to be taken again due to poor quality of the isolated DNA transpiring from either the quality of the blood punch or manual mistakes during DNA isolation. The SMN1 exon 7 homozygous deletion was identified in two individuals, which was subsequently confirmed by multiplex ligation-dependent probe amplification. When a NBS sample is taken 48 to 72 h after birth and transported to the laboratory within two working days after collection according to legal requirements, DNA test results can be reported to healthcare professionals before the 12th day of life. Expansion of our SMA 5q NBS procedure to the whole of Latvia is feasible and would facilitate early diagnosis and result in more effective treatment. We strongly advocate that SMA is added to the national Latvia Recommended Uniform Screening Panel.publishersversionPeer reviewe

Role of Single Nucleotide Variants in FSHR, GNRHR, ESR2 and LHCGR Genes in Adolescents with Polycystic Ovary Syndrome

Funding Information: Funding: The study was financially supported by a Riga Stradins University internal research grant. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Background: Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women, affecting up to 16.6% of reproductive-age women. PCOS symptoms in adolescents comprise oligomenorrhoea/amenorrhoea and biochemical and/or clinical hyperandrogenism. Long-term health risks of PCOS patients include infertility, metabolic syndrome, type 2 diabetes and cardiovascular disease. Genetic factors have been proven to play a role in development of the syndrome and its symptoms. Objective: To investigate single nucleotide variants (SNVs) in the GNRHR, ESR2, LHCGR and FSHR genes in adolescent patients with PCOS and their association with PCOS symptoms. Methods: We conducted a cross-sectional study comprising of 152 adolescents: 63 patients with PCOS, 22 patients at risk of developing PCOS and 67 healthy controls. Participants were recruited from out-patients attending a gynaecologist at the Children’s Clinical University Hospital, Riga, Latvia, between January 2017 and December 2020. Genomic DNA was extracted from whole blood, and SNVs in the GNRHR, ESR2, LHCGR and FSHR genes were genotyped. The distributions of SNV genotypes were compared among the three groups and genotype-phenotype associations within the PCOS group were evaluated. Results: No statistically significant differences were found in the distributions of genotypes for GNRHR (rs104893837), ESR2 (rs4986938), LHCGR (rs2293275) and FSHR (rs6166, rs6165, rs2349415) among PCOS patients, risk patients and healthy controls. Within the PCOS group, ESR2 rs4986938 minor allele homozygous patients had a significantly higher level of total testosterone than major allele homozygous patients and heterozygous patients. A significantly higher total testosterone level was also observed in PCOS patients carrying the LHCGR rs2293275 minor allele compared with major allele homozygous patients. Conclusions: The SNVs ESR2 rs4986938 and LHCGR rs2293275 play a role in the phenotypic characteristics of PCOS. To fully uncover their influence on the development of PCOS and its symptoms, further studies of larger cohorts and a follow up of this study sample through to adulthood are required. Furthermore, studies of adolescent PCOS patients conducted prior to the latest European Society of Human Reproduction and Embryology (ESHRE) criteria (2018) should be re-evaluated as the study groups might include risk patients according to these updated criteria, thereby potentially significantly impacting the published results.publishersversionPeer reviewe

Newborn Screening for Spinal Muscular atrophy : first results of a Pilot Study in Latvia

publishersversionNon peer reviewe