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Background: The problem of vitamin D deficiency is particularly relevant for the entire territory of Russia, since most parts of the country are located above the 42nd geographical latitude and the residents are therefore at risk of vitamin D deficiency. Despite the urgency of the problem, a comprehensive study of the molecular and genetic mechanisms and exogenous factors of vitamin D deficiency in children living in various geographical areas of the Russian Federation has not been conducted. Different variants in the loci of the genes responsible for the synthesis, hydroxylation, and transport of vitamin D (such as DHCR7, CYP2R1, CYP24A1, and GC), as well as VDR gene polymorphisms may also be associated with the risk of vitamin D deficiency. The aim of this study was to analyze the influence of exogenous factors on the blood levels of 25-hydroxyvitamin D (25(OH)D) in children of three regions of the Russian Federation, as well as the relationship of blood 25(OH)D levels with polymorphic variants of cytochrome P450 genes and VDR gene.Methods: We conducted blood 25(OH)D level analysis in 333 healthy children and adolescents in three regions located in different geographical zones of the Russian Federation. We studied the polymorphic variants c.1075A>C (I359L, rs1057910, CYP2C9*3) and c.430C>T (R144C, rs1799853, CYP2C9*2) in the CYP2C9 gene, c.1334T>C (M445T, rs4986910, CYP3A4*3), and CYP3A4*1B (c.-392C>T, rs2740574) in the CYP3A4 gene, 1846G>A, (rs3892097, CYP2D6*4) in the CYP2D6gene, TaqI (NM_000376.2: c.1056T>C; rs731236), FokI (NM_000376.2:c.2T>C; (rs2228570), and BsmI (NM_000376.2: c.1024+283G>A; rs1544410) in the VDR gene. We also analyzed the influence of exogenous factors on the level of 25(OH)D in children of the three study regions, as well as the relationship of the level of 25(OH)D with variants CYP2C9*2 (c.430C>T; R144C), CYP2C9*3 (c,1075A>C; I359L), CYP2D6*4 (1846G>A), CYP3A4*3 (c.1334T>C), and CYP3A4*1B (c.-392C>T) and rs731236, rs2228570 and rs1544410 in the VDR gene.Results: We found that the blood level of 25(OH)D depended on the geographical location and the number of sunny days per year. The average blood level of 25(OH)D in adolescent boys was statistically significantly lower than in girls of this age group. The level of 25(OH)D also significantly depended on the prophylactic dose of cholecalciferol administered to the subjects. In the study, it was shown that a dose of cholecalciferol ≥1,000 IU per day can achieve a normal level of 25(OH)D in healthy children. We found no statistically significant association between single-nucleotide polymorphic variants of cytochrome P450 genes (CYP2C9*3, CYP3A4*3, CYP2C9*2, CYP2D6*4, and CYP3A4*1B) and blood level of 25(OH)D in the subjects. We also did not find a relationship between the TaqI, FokI, and BsmI polymorphisms of the VDR gene and serum 25(OH)D concentration.Conclusion: Exogenous factors (time of year, place of residence, and prophylactic administration of cholecalciferol), as well as endogenous factors (age and sex), play a determining role in the development of vitamin D deficiency and insufficiency; in contrast to genetic factors—polymorphic variants of the genes of xenobiotic phase 1 enzymes (CYP2C9, CYP2C19, CYP2D6, and CYP3A4) and the VDR gene—which do not play such role. This study shows the need to create a diagnostic algorithm for Vitamin D deficiency based on the age, season of the year, and prophylactic dose of cholecalciferol.

The goal was to study the phenotypic manifestations of c.3844T>C (p.Trp1282Arg, W1282R) variant, a CF-causing mutation, in patients from the Russian Federation. Clinical manifestations and complications (the age at CF diagnosis, sweat test, pancreatic status, lung function, microbial infection, body mass index (BMI), the presence of meconium ileus (MI), diabetes, and severe liver disease) were compared in four groups: group 1—patients carrying c.3844T>C and severe class I or II variant in trans; group 2—3849+10kbC>T/F508del patients; group 3—F508del/F508del patients; and group 4—patients with W1282R and “mild” variant in trans. Based on the analyses, W1282R with class I or II variant in trans appears to cause at least as severe CF symptoms as F508del homozygotes as reflected in the early age of diagnosis, high sweat chloride concentration, insufficient pancreatic function, and low lung function, in contrast to 3849+10kbC-T/F508del compound heterozygotes having milder clinical phenotypes. The W1282R pathogenic variant is seemed to lead to severe disease phenotype with pancreatic insufficiency similarly to the F508del homozygous genotype.

The distribution and frequency of the CFTR gene mutations vary considerably between countries and ethnic groups. Russians are an East Slavic ethnic groups are native to Eastern Europe. Russians, the most numerous people of the Russian Federation (RF), make about 80% of the population. The aim is to reveal the molecular causes of CF in ethnic Russian patients as comprehensively as possible. The analysis of most common CFTR mutations utilized for CF diagnosis in multiethnic RF population accounts for about 83% of all CF-causing mutations in 1384 ethnic Russian patients. Variants c.1521_1523delCTT (F508del), c.54-5940_273+10250del21kb (CFTRdele2,3), c.2012delT (2143delT), c.2052_2053insA (2184insA), and c.3691delT (3821delT) are most typical for CF patients of Russian origin. DNA of 154 CF patients, Russian by origin, in whom at least one mutant allele was not previously identified (164 CF alleles), was analyzed by Sanger sequencing followed by the multiplex ligase-dependent probe amplification (MLPA) method. In addition to the 29 variants identified during the previous test for common mutations, 91 pathogenic CFTR variants were also revealed: 29 missense, 19 nonsense, 14 frame shift in/del, 17 splicing, 1 in frame ins, and 11 copy number variations (CNV). Each of the 61 variants was revealed once, and 17 twice. Each of the variants c.1209G&gt, C (E403D), c.2128A&gt, T (K710X), c.3883delA (4015delA), and c.3884_3885insT (4016insT) were detected for three, c.1766+1G&gt, A (1898+1G&gt, A) and c.2834C&gt, T (S945L) for four, c.1766+1G&gt, C (1898+1G&gt, C) and c.(743+1_744-1)_(1584+1_1585-1)dup (CFTRdup6b-10) for five, c.2353C&gt, T (R785X) and c.4004T&gt, C (L1335P) for six, c.3929G&gt, A (W1310X) for seven, c.580-1G&gt, T (712-1G&gt, T for eight, and c.1240_1244delCAAAA (1365del5) for 11 unrelated patients. A comprehensive analysis of CFTR mutant alleles with sequencing followed by MLPA, allowed not only the identification of 163 of 164 unknown alleles in our patient sample, but also expansion of the mutation spectrum with novel and additional frequent variants for ethnic Russians.

Significant progress has been made in cystic fibrosis (CF) treatment using new antibiotic (AB) therapy options. However, the spectrum of bacterial pathogens and their susceptibility to AB have changed as well. Study objective: to investigate microflora prevailing in CF subjects’ respiratory tract (RT) change over 15 years. CF subjects’ sputum culture test results collected from 2000 till 2015 were analyzed. There were 9774 samples reviewed, 16703 strains identified. “MYCROB” system of microbiological monitoring was used for entry, statistical processing and analysis of data. Study results: S. aur. identification dropped from 42% (2000-03) to 32% (2012-15). P. aerug. from 24% (2000-03) to 11% (2011-15), P. aerug. muc. from 17% (2000-03) to 9% (2012-15). Incidence of chronic P. aerug. infection in CF children decreased from 57% in 1999 to 26% in 2011 and even 14% in 2014. MRSA identification growth from 6% (2000-03) to 9,5% (2008-11) and further to 12% (2012-15) is worrisome. B. cepacia comp. identification grew from 1% (2000-03) to 11% (2008-11) and 7% (2012-15). S. maltophilia identification dropped from 6% (2000-03) to 3% (2012-15). A. xylosoxidans identification grew from 3% (2000-03) to 5% (2012-15). The data presented demonstrate significant change in the distribution of the species identified. In parallel with P. aerug, and P. aerug. muc. identification frequency drop and reduction of chronic P. aerug. infection cases, there is a tendency to higher incidence of B.cepacia complex, A. xylosoxidans and MRSA identification which is quite challenging for further CF subjects care.