A New Baltic Population-Specific Human Genetic Marker in the PMCA4 Gene.

OBJECTIVES: The PMCA gene family consists of 4 genes and at least 21 splice variants; among these, the Ca2+ ATPase 4 (PMCA4) gene encodes a plasma membrane protein abundantly expressed in several tissues, including the kidney, heart, and sperm. Knockout of PMCA4 causes infertility due to immotile sperm in mouse models. We therefore investigated variants in this gene for potential association with infertility in groups of Estonian (n = 191) and Latvian (n = 92) men with reduced sperm motility. METHODS: All exons, exon-intron boundaries, 5' and 3' untranslated regions, and the promoter region of the PMCA4 gene were analysed by direct sequencing for a group of Estonian infertile men. Genotyping of guanine and adenine alleles of rs147729934 was performed, using a custom-designed TaqMan® probe for a group of Latvian infertile men as well as additional groups from Latvia and several groups of people with proven ethnicity from the Baltic region. RESULTS: Although we did not identify any significant associations between variants in the gene and infertility, our results indicated that in all studied Latvian and Estonian groups the adenine allele of the variant rs147729934 was present at a higher frequency than expected. Analysis of additional samples indicated that the adenine allele of rs147729934 likely originated once in the modern-day Baltic or western Russia area, as the frequency of the minor adenine allele observed in this region is remarkably higher than that in the general European population. CONCLUSIONS: Our results revealed no significant difference in frequencies of genetic variants in PMCA4 gene between men with normal and those with reduced sperm motility. The adenine allele of the variant rs147729934 is potentially an informative tool for future population studies concerning ancient Baltic and Finno-Ugric history.

Homocysteine and MTHFR C677T polymorphism in children and adolescents with psychotic and mood disorders.

BACKGROUND: High level of homocysteine (Hcy) is risk factor of schizophrenia and mood disorders. AIM: The aim was to detect a serum level of Hcy, examine the associations between the level of Hcy, methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism and clinical properties for patients with schizophrenia, mood disorders and in a control group. MATERIAL AND METHODS: There were 88 patients with schizophrenia, 28 with affective disorders and 94 from the control group. The Hamilton Anxiety Scale (HAM-A) was performed to study anxiety, the Hamilton Depression Scale (HAM-D) to study depression and the Brief Psychiatric Rating Scale (BPRS) to study severity of schizophrenia. The level of Hcy was stated by isocratic high-performance liquid chromatography (HPLC) system with fluorometric detection. DNA isolation from venous blood was performed by the phenol-chloroform method. RESULTS: The levels of B12 vitamin and folic acid were within normal limits for all the patients. The average level of Hcy was 11.94 ± 5.6 µmol/l for patients with schizophrenia and 11.65 ± 3.3 µmol/l for patients with affective disorders, vs. 6.80 ± 2.93 µmol/l in a control group. The highest level of Hcy has been observed in patients with an episodic-recurrent course of schizophrenia, paranoid schizophrenia-continuous, particularly in patients with CT genotype (r = - 0.58; P < 0.01). In the given diagnostic groups, the highest level of anxiety was observed. CONCLUSIONS: The level of Hcy is higher in the blood of a heterozygotic person who becomes ill with schizophrenia, and the process of the illness is more serious and with more typical affective disorders.

Variation in FGF1, FOXE1, and TIMP2 genes is associated with nonsyndromic cleft lip with or without cleft palate.

BACKGROUND: Nonsyndromic cleft lip with or without cleft palate (CL/P) is a common complex birth defect caused by the interaction between multiple genes and environmental factors. METHODS: Five hundred and eighty-seven single nucleotide polymorphisms in 40 candidate genes related to orofacial clefting were tested for association with CL/P in a clefting sample composed of 300 patients and 606 controls from Estonian, Latvian, and Lithuanian populations. RESULTS: In case-control comparisons, the minor alleles of FGF1 rs34010 (p = 4.56 × 10(-4) ), WNT9B rs4968282 (p = 0.0013), and FOXE1 rs7860144 (p = 0.0021) were associated with a decreased risk of CL/P. Multiple haplotypes in FGF1, FOXE1, and TIMP2 and haplotypes in WNT9B, PVRL2, and LHX8 were associated with CL/P. The strongest association was found for protective haplotype rs250092/rs34010 GT in the FGF1 gene (p = 5.01 × 10(-4) ). The strongest epistatic interaction was observed between the COL2A1 and WNT3 genes. CONCLUSIONS: Our results provide for the first time evidence implicating FGF1 in the occurrence of CL/P, and support TIMP2 and WNT9B as novel loci predisposing to CL/P. We have also replicated recently reported significant associations between variants in or near FOXE1 and CL/P. It is likely that variation in FOXE1, TIMP2, and the FGF and Wnt signaling pathway genes confers susceptibility to nonsyndromic CL/P in Northeastern European populations.

Association studies of candidate genes and cleft lip and palate taking into consideration geographical origin.

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.

Genetic variants in COL2A1, COL11A2, and IRF6 contribute risk to nonsyndromic cleft palate.

BACKGROUND: Orofacial clefts are among the most common birth defects with a strong genetic component. Nonsyndromic cleft palate (NSCP) is a complex malformation determined by the interaction between multiple genes and environmental risk factors. METHODS: We conducted a case-control association study to investigate the role of 40 candidate genes in predisposition to orofacial clefting. Five hundred ninety-one haplotype tagging single nucleotide polymorphism (tagSNPs) were genotyped in a clefting sample from the Baltic region, composed of 104 patients with nonsyndromic cleft palate and 606 controls from an Estonian, Latvian, and Lithuanian population. RESULTS: In case-control comparisons, the minor alleles of IRF6 rs17389541 (p = 5.45 × 10(-4)) and COL2A1 rs1793949 (p = 7.26 × 10(-4)) were associated with increased risk of NSCP. Multiple haplotypes in COL2A1 and COL11A2 and haplotypes in WNT3, FGFR1, and CLPTM1were associated with NSCP. The strongest associations were found for IRF6 haplotype rs17389541/rs9430018 GT (p = 2.23 × 10(-4)) and COL2A1 haplotype rs12822608/rs6823 GC (p = 3.68 × 10(-4)). The strongest epistatic interactions were observed between MSX1 and BMP2, FGF1 and PVRL2, and COL2A1 and FGF2 genes. CONCLUSIONS: This study provides for the first time evidence of the implication of IRF6, COL2A1, and WNT3 in the occurrence of NSCP. It is likely that variation in cartilage collagen II and XI genes, IRF6, and the Wnt and FGF signaling pathway genes contributes susceptibility to nonsyndromic cleft palate in Northeastern European populations.

Gut colonization with extended-spectrum ß-lactamase-producing Enterobacteriaceae may increase disease activity in biologic-naive outpatients with ulcerative colitis: an interim analysis.

BACKGROUND: Certain Enterobacteriaceae strains have been associated with the development of ulcerative colitis (UC). Extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae are the most commonly found multi-drug-resistant (MDR) bacteria colonizing the gut in UC patients and might trigger a more severe disease activity in UC patients. OBJECTIVE: The aim of this study was to evaluate whether disease activity is higher in UC patients with gut colonization with ESBL-producing Enterobacteriaceae. MATERIALS AND METHODS: A cross-sectional, pilot study was carried out in a tertiary medical center in Latvia. Demographic data were collected; UC disease activity and extent were evaluated according to the full Mayo score, Montreal classification, and adapted Truelove and Witt's index. Rectal swabs with fecal biomaterial were collected, ESBL-producing Enterobacteriaceae were isolated, and bacterial plasmid genes responsible for ESBL production, blaCTX-M, blaTEM, and blaSHV, were detected. UC disease activity was compared in patients with and without gut colonization with ESBL-producing Enterobacteriaceae. RESULTS: A total of 65 patients with UC were included in the initial analysis. Gut colonization with ESBL-producing Enterobacteriaceae was found in seven (11%) patients - mostly Escherichia coli [5 (71%)] containing the blaCTX-M bacterial plasmid gene. Patients with gut colonization with ESBL-producing Enterobacteriaceae had more severe disease compared with patients without gut colonization according to the full Mayo score (5.86 vs. 3.40; P=0.015), Montreal classification (moderate disease vs. clinical remission; P=0.031), and adapted Truelove and Witt's index (moderate disease vs. mild disease; P=0.008). CONCLUSION: Gut colonization with ESBL-producing Enterobacteriaceae may increase UC disease activity. Further research is needed to analyze the possible confounding factors that could contribute toward this outcome.

Genetic variation spectrum in ATP7B gene identified in Latvian patients with Wilson disease.

BACKGROUND: Wilson disease (WD) is an autosomal recessive disorder of copper metabolism caused by allelic variants in ATP7B gene. More than 500 distinct variants have been reported, the most common WD causing allelic variant in the patients from Central, Eastern, and Northern Europe is H1069Q. METHODS: All Latvian patients with clinically confirmed WD were screened for the most common mutation p.H1069Q by PCR Bi-PASA method. Direct DNA sequencing of gene ATP7B (all 21 exons) was performed for the patients with WD symptoms, being either heterozygous for H1069Q or without it on any allele. RESULTS: We identified 15 different allelic variants along with eight non-disease-causing allelic variants. Based on the gene molecular analysis and patients' clinical data variant p.His1069Gln was found in 66.9% of WD alleles. Wide clinical variability was observed among individuals with the same ATP7B genotype. The results of our study confirm that neurological manifestations of WD are typically present later than the liver disease but no significant association between the presence/absence of the most common genetic variant and mode of initial WD presentation or age at presentation was identified. CONCLUSIONS: (1) The most prevalent mutation in Latvian patients with Wilson disease was c.3207C>A (p.His1069Gln); (2) No significant phenotype-genotype correlation was found in Latvian patients with Wilson disease; (3) The estimated prevalence of Wilson disease in Latvia is 1 of 24,000 cases which is higher than frequently quoted prevalence of 1: 30,000.

Analysis of possible genetic risk factors contributing to development of childhood acute lymphoblastic leukaemia in the Latvian population.

INTRODUCTION: Childhood acute lymphoblastic leukaemia (ALL) is a complex disease caused by a combination of genetic susceptibility and environmental exposure. Previous genome-wide association studies have reported several single nucleotide polymorphisms (SNPs) associated with the incidence of ALL. Several variations in genes encoding enzymes involved in carcinogenesis are suggested as being associated with an increased risk of ALL development. MATERIAL AND METHODS: We enrolled 77 paediatric ALL patients and 122 healthy controls, and in addition parental DNA was also available for 45 probands. SNPs rs10821936 (ARID5B), rs4132601 (IKZF1), rs2239633 (CEBPE), rs3731217 (CDKN2A) and rs1800566 (NQO1) and the presence of GSTT1 and GSTM1 null variants were detected. For statistical analysis the hybrid method of two designs 'Haplin' was used as well as linkage disequilibrium for family-based association studies. RESULTS: We identified the SNP rs10821936 in the ARID5B gene as being statistically significantly associated with childhood ALL, especially if the C allele is in a homozygous state, relative risk (RR) 4.65, 95% CI: 2.03-10.6, p = 0.0006. Statistically significant differences were not found in other SNPs. We found risk combinations including all five variations, the strongest association being found in a combination where all five genetic variants are in a homozygous state, CCTTTTTTCC, p = 0.032. CONCLUSIONS: The identified SNP rs10821936 could serve as a potential risk marker for childhood ALL development. Further studies in an independent population are needed for verification.

Association between inherited monogenic liver disorders and chronic hepatitis C.

AIM: To determine the frequencies of mutations that cause inherited monogenic liver disorders in patients with chronic hepatitis C. METHODS: This study included 86 patients with chronic hepatitis C (55 men, 31 women; mean age at diagnosis, 38.36 ± 14.52 years) who had undergone antiviral therapy comprising pegylated interferon and ribavirin. Viral load, biochemical parameter changes, and liver biopsy morphological data were evaluated in all patients. The control group comprised 271 unrelated individuals representing the general population of Latvia for mutation frequency calculations. The most frequent mutations that cause inherited liver disorders [gene (mutation): ATP7B (H1069Q), HFE (C282Y, H63D), UGT1A1 (TA)7, and SERPINA1 (PiZ)] were detected by polymerase chain reaction (PCR), bidirectional PCR allele-specific amplification, restriction fragment length polymorphism analysis, and sequencing. RESULTS: The viral genotype was detected in 80 of the 86 patients. Viral genotypes 1, 2, and 3 were present in 61 (76%), 7 (9%), and 12 (15%) patients, respectively. Among all 86 patients, 50 (58%) reached an early viral response and 70 (81%) reached a sustained viral response. All 16 patients who did not reach a sustained viral response had viral genotype 1. Case-control analysis revealed a statistically significant difference in only the H1069Q mutation between patients and controls (patients, 0.057; controls, 0.012; odds ratio, 5.514; 95%CI: 1.119-29.827, P = 0.022). However, the H1069Q mutation was not associated with antiviral treatment outcomes or biochemical indices. The (TA) 7 mutation of the UGT1A1 gene was associated with decreased ferritin levels (beta regression coefficient = -295.7, P = 0.0087). CONCLUSION: Genetic mutations that cause inherited liver diseases in patients with hepatitis C should be studied in detail.

Lack of association between polymorphisms in genes MTHFR and MDR1 with risk of childhood acute lymphoblastic leukemia.

BACKGROUND: Acute lymphoblastic leukemia (ALL) is a complex disease caused by interactions between hazardous exogenous or/and endogenous agents and many mild effect inherited susceptibility mutations. Some of them are known, but their functional roles still requireinvestigation. Age is a recognized risk factor; children with disease onset after the age of ten have worse prognosis, presumably also triggered by inherited factors. MATERIALS AND METHODS: The MDR1 gene polymorphisms rs1045642, rs2032582 and MTHFR gene polymorphisms rs1801131 and rs1801133 were genotyped in 68 ALL patients in remission and 102 age and gender matched controls; parental DNA samples were also available for 42 probands. RESULTS: No case control association was found between analyzed polymorphisms and a risk of childhood ALL development. Linkage disequilibrium was not observed in a family-based association study either. Only marginal association was observed between genetic marker rs2032582A and later disease onset (p=0.04). CONCLUSIONS: Our data suggest that late age of ALL onset could be triggered by mild effect common alleles.

Elevated serum levels of homocysteine as an early prognostic factor of psychiatric disorders in children and adolescents.

Background and Goal. The aim was to examine the serum levels of homocysteine (Hcy) and their associations with the methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism in patients with schizophrenia and mood disorders as well as controls. Materials and Methods. There were 198 patients: 82 with schizophrenia spectrum disorders, 22 with mood disorders, and 94 controls. The level of Hcy was determined by an isocratic high-performance liquid chromatography system. MTHFR C677T polymorphism was analysed using the restriction fragment length polymorphism-polymerase chain reaction method. Results. The average level of Hcy was 11.94 ± 5.6 µmol/L for patients with schizophrenia, 11.65 ± 3.3 µmol/L for patients with affective disorders, versus 6.80 ± 2.93 µmol/L in a control. The highest level of Hcy has been observed in patients with episodic-recurrent course of schizophrenia (11.30 ± 7.74 µmol/L), paranoid schizophrenia continuous (12.76 ± 5.25 µmol/L), and in patients with affective disorders (11.65 ± 3.26 µmol/L). An association between the MTHFR gene C677T polymorphism and Hcy level was found by linear regression analysis (r = 1.41, P = 0.029). Conclusions. The data indicate a link between Hcy levels and schizophrenia and mood disorders. No associations between the level of Hcy in patients with schizophrenia and mood disorders and the MTHFR C677T polymorphism were found.