Bronchial asthma (BA) exhibits varying prevalence across global populations, prompting a comprehensive investigation into genetic and environmental determinants. Vitamin D is a potent immunomodulator capable of suppressing inflammatory signals in several cell types involved in the asthmatic response; it exerts effects on the immune system by binding to the nuclear vitamin D receptor (VDR). VDR gene genetic variations are affecting serum vitamin D levels with a possible role in the BA risk. The current study aimed to examine the complex interaction of various factors (genetic background, serum vitamin D levels, and geographic location) to identify differences in the influence of these factors on the susceptibility to asthma between populations at different latitudes. Focusing on Eastern European cohorts from Latvia and Lithuania and comparing them with published data on East Asian populations, we explore the impact of VDR gene polymorphisms on BA susceptibility. Genotyping four key VDR SNPs and assessing their association with 25-hydroxyvitamin D levels, our study unveils significant associations of the studied loci with the risk of asthma—both risk-reducing and increasing effects, differently distributed between Baltic and East Asian populations. The functional effects of in silico VDR gene genetic variations are also identified and discussed.

Myostatin (MSTN), a member of the TGFβ superfamily, negatively affects skeletal muscle growth and controls muscle development at stages of pre-natal muscle growth. Marker-assisted selection with molecular markers of the MSTN gene can be used in animal husbandry for higher-quality and more economically profitable lambs. The study aims to identify multi-locus genotypes within the MSTN gene regions as molecular markers for fattening, feed efficiency, and carcass traits in Latvian sheep. This analysis was conducted on 76 intensively fattened male lambs representing six breeds in Latvia. Nine genotypes were identified based on four SNPs in the promoter and exon 1 regions, while six and four SNPs in introns 1 and 2 led to the formation of 14 and 10 genotypes, respectively. Six genotypes identified in the 3′UTR were significantly linked to traits such as birth weight, slaughter yield, muscle development, fat depth, average daily gain, dry matter intake, and feed efficiency. Genotypes of intron 1 were associated with slaughter yield, while genotypes of intron 2 were linked to fat depth, dry matter intake, and residual weight gain. The study concludes that MSTN gene SNPs can be used in selection to enhance sheep breeds in Latvia and improve economic outcomes for breeders.

Vitamin D is crucial for immune regulation, and its deficiency is linked to multiple sclerosis (MS). The GC gene encodes Vitamin D Binding Protein (VDBP), which regulates vitamin D transport and bioavailability. This study examines the association of GC polymorphisms (rs7041, rs4588) with MS susceptibility and their impact on 25-hydroxyvitamin D [25(OH)D] levels in a Latvian cohort. This case–control study included 296 MS patients and 253 healthy controls. Genotyping of rs7041 and rs4588 was conducted using restriction fragment length polymorphism analysis and validated by Sanger sequencing. Plasma 25(OH)D levels were measured in 131 MS patients using an enzyme-linked immunosorbent assay. Statistical analysis included Hardy–Weinberg equilibrium testing, Fisher’s exact test, allelic and genotypic frequency comparisons to assess MS risk, and the Kruskal–Wallis test for 25(OH)D level differences among genotypes. Our findings indicate that the rare rs7041-T and rs4588-A alleles, along with their corresponding haplotypes, exhibit a protective effect against MS (p < 0.001; OR = 0.65 for rs4588-A; p < 0.01; OR = 0.70 for rs7041-T). Conversely, the common rs7041-G and rs4588-C alleles were associated with an increased MS risk (p < 0.05). Individuals with the Gc1F/1F isotype had the highest average 25(OH)D levels (29.31 ng/mL), while Gc1S/2 carriers had the lowest (21.53 ng/mL). Our results indicate that GC polymorphisms may influence the susceptibility of Latvians to MS and vitamin D status.

The Latvian Dark-head (Latvijas tumšgalve; LT) is the only sheep breed developed in Latvia. It is fully adapted to the country’s climatic conditions. As the sole national breed, it holds notable cultural importance by supporting traditional husbandry practices, landscape preservation, and regional identity. However, the dominance of commercial breeds threatens local genetic resources. Small-scale farms, where the LT population is concentrated, are especially vulnerable to population decline and possible extinction. This study assesses the genetic diversity within the LT breed and compares it with that of other major sheep breeds in Latvia. For the first time, lambs from sire rams of major breeds in Latvia underwent genotyping using the Illumina Ovine SNP50 BeadChip^® (San Diego, CA, USA). Genetic diversity was assessed with minor allele frequency (MAF) analysis. Breed-specific markers were identified by detecting fixed SNPs (MAF = 0) unique to each breed. In total, 27,561 highly polymorphic SNPs (MAF 0.3–0.5) were identified in the LT breed. This indicates substantial genetic differentiation from other sheep breeds raised in Latvia. Among the analyzed SNPs, 2668 (5.45%) were fixed in the LT breed. Of these, 55–131 were unique compared with other breeds. The OvineSNP50 panel is an effective tool for characterizing the genetic structure of the LT breed. It enables the detection of distinct genetic traits and interbreed differences. These results establish a genomic basis for targeted conservation and selective breeding strategies. Such strategies maintain the genetic integrity and competitiveness of the Latvian Dark-head.