Knockout of M-LP/Mpv17L, a newly identified atypical PDE, induces physiological afferent cardiac hypertrophy in mice.

M-LP/Mpv17L (Mpv17-like protein) is an atypical cyclic nucleotide phosphodiesterase (PDE) without the molecular structure characteristic of the PDE family. Deficiency of M-LP/Mpv17L in mice has been found to result in development of ß-cell hyperplasia and improved glucose tolerance. Here, we report another phenotype observed in M-LP/Mpv17L-knockout (KO) mice: afferent cardiac hypertrophy. Although the hearts of M-LP/Mpv17L-KO mice did not differ in size from those of wild-type mice, there was marked narrowing of the left ventricular lumen and thickening of the ventricular wall. The diameter and cross-sectional area of cardiomyocytes in 8-month-old M-LP/Mpv17L-KO mice were increased 1.16-fold and 1.35-fold, respectively, relative to control mice, but showed no obvious abnormalities of cell structure, fibrosis or impaired cardiac function. In 80-day-old KO mice, the expression of hypertrophic marker genes, brain natriuretic peptide (BNF), actin alpha cardiac muscle 1 (ACTC1) and actin alpha 1 skeletal muscle (ACTA1), as well as the Wnt/ß-catenin pathway target genes, lymphoid enhancer-binding factor-1 (LEF1), axis inhibition protein 2 (AXIN2) and transcription factor 7 (TCF7), was significantly up-regulated relative to control mice, whereas fibrosis-related genes such as fibronectin 1 (FN1) and connective tissue growth factor (CTGF) were down-regulated. Western blot analysis revealed increased phosphorylation of molecules downstream of the cAMP/PKA signaling pathway, such as ß-catenin, ryanodine receptor 2 (RyR2), phospholamban (PLN) and troponin I (cTnI), as well as members of the MEK1-ERK1/2 signaling pathway, which is strongly involved in afferent cardiac hypertrophy. Taken together, these findings indicate that M-LP/Mpv17L is one of the PDEs actively functioning in the heart and that deficiency of M-LP/Mpv17L in mice promotes physiological cardiac hypertrophy.

Identification of novel variants in HLA class II region related to HLA DPB1 expression and disease progression in patients with chronic hepatitis C.

Recent genome-wide studies have demonstrated that HLA class II gene may play an important role in viral hepatitis. We studied genetic polymorphism and RNA expression of HLA class II genes in HCV-related liver diseases. The study was performed in groups consisting of 24 patients with HCV-related liver disease (12 of persistent normal ALT: PNALT group and 12 of advanced liver disease: ALD group) and 26 patients without HCV infection (control group). In PBMC samples, RNA expression of HLA class II genes (HLA-DPA1, DPB1, DQA1, DQB1, and DRB1) was analyzed by real-time RT-PCR. Furthermore, 22 single nucleotide polymorphisms (SNPs) in HLA class II gene and two SNPs in IL28B gene were genotyped by genetic analyzer (GENECUBE®). In expression analysis, only DPB1 level was significantly different. Mean expression level of DPB1gene in control group was 160.0, PNALT group 233.8, and ALD group 465.0 (P < 0.01). Of 24 SNPs, allele frequencies were statistically different in two SNPs (rs2071025 and rs3116996) between PNALT groups and ALD group (P < 0.01). In rs2071025, TT genotype was frequently detected in ALD group and expression level was significantly higher than the other genotypes (449.2 vs 312.9, P < 0.01). In rs3116996, TA or TT (non AA) genotype was frequently detected in ALD group and expression level was significantly higher than genotype AA (457.1 vs 220.9, P < 0.01). Genotyping and expression analysis in HLA class II gene revealed that two SNPs of HLA-DPB1 (rs2071025 and rs3116996) were significantly correlated to RNA expression and progression of HCV-related liver diseases.

Functional Single Nucleotide Polymorphisms (SNPs) in the Genes Encoding the Human Deoxyribonuclease (DNase) Family Potentially Relevant to Autoimmunity.

OBJECTIVE: To continue our previous investigations, we have extensively investigated the function of the 61, 41, and 35 non-synonymous single nucleotide polymorphisms (SNPs) in the human genes encoding DNASE1, DNASE1L3, and DNASE2, respectively, potentially relevant to autoimmune diseases. METHODS: The site-directed mutagenesis was employed to amino acid-substituted constructs corresponding to each SNP. The COS-7 cells were transfected with each vector and DNase activity was assayed by the single radial enzyme diffusion method. By using PolyPhen-2, changes in the DNase function of each non-synonymous SNP were predicted. Genotyping of all the non-synonymous SNPs was performed in 14 different populations including 3 ethnic groups using the polymerase chain reaction followed by the restriction fragment length polymorphism method. RESULTS: Expression analysis demonstrated these SNPs to be classified into four categories with regard to the effect on DNase activity: SNPs not affecting the activity level, ones reducing it, ones abolishing it, and ones elevating it. In particular, 9, 5, and 4 SNPs producing a loss-of-function variant of the enzymes in DNASE1, DNASE1L3, and DNASE2, respectively, were confirmed. SNPs producing DNase loss of function can be estimated by PolyPhen-2 to be "probably damaging" with a high accuracy of prediction. Almost all of these functional SNPs producing a loss of function or substantially low activity-harboring forms exhibited a mono-allelic distribution in all of the populations. CONCLUSION: A minor allele of functional SNPs, despite the remarkably low genetic heterogeneity of the SNPs, might be a genetic risk factor for autoimmune diseases.

Association of XRCC1 polymorphisms with arsenic methylation.

The associations of four single nucleotide polymorphisms (p.Arg194Trp, p.Arg280His, p.Pro206Pro, and p.Arg399Gln) in X-ray repair cross-complementing group 1 with urinary arsenic metabolites and 8-hydroxy-2'-deoxyguanosine (8-OHdG) were investigated in a Vietnamese population (n = 100). Individuals with genotype AA in p.Pro206Pro showed significantly higher urinary monomethylarsonic acid (MMA(V)) and lower dimethylarsinic acid (DMA(V))/MMA(V) ratio than genotype AG. As for p.Arg399Gln, both Arg/Arg homozygous subjects and Arg/Gln heterozygous individuals showed a significantly higher urinary inorganic As percentage and lower 8-OHdG concentrations than Gln/Gln homozygous. Our results suggested that Arg399Gln is a functional SNP that may be related to DNA repair activity.

Expression of ABO blood-group genes is dependent upon an erythroid cell-specific regulatory element that is deleted in persons with the B(m) phenotype.

The ABO blood group is of great importance in blood transfusion and organ transplantation. However, the mechanisms regulating human ABO gene expression remain obscure. On the basis of DNase I-hypersensitive sites in and upstream of ABO in K562 cells, in the present study, we prepared reporter plasmid constructs including these sites. Subsequent luciferase assays indicated a novel positive regulatory element in intron 1. This element was shown to enhance ABO promoter activity in an erythroid cell-specific manner. Electrophoretic mobility-shift assays demonstrated that it bound to the tissue-restricted transcription factor GATA-1. Mutation of the GATA motifs to abrogate binding of this factor reduced the regulatory activity of the element. Therefore, GATA-1 appears to be involved in the cell-specific activity of the element. Furthermore, we found that a partial deletion in intron 1 involving the element was associated with B(m) phenotypes. Therefore, it is plausible that deletion of the erythroid cell-specific regulatory element could down-regulate transcription in the B(m) allele, leading to reduction of B-antigen expression in cells of erythroid lineage, but not in mucus-secreting cells. These results support the contention that the enhancer-like element in intron 1 of ABO has a significant function in erythroid cells.

Five non-synonymous SNPs in the gene encoding human deoxyribonuclease I-like 2 implicated in terminal differentiation of keratinocytes reduce or abolish its activity.

Several non-synonymous SNPs in the human deoxyribonuclease I-like 2 (DNase 1L2) gene responsible for DNA degradation during terminal differentiation of epidermal keratinocytes have been identified. However, only limited population data are available, and furthermore the effect of these SNPs on the DNase 1L2 activity remains unknown. Genotyping of all of the 17 SNPs was performed using the PCR-RFLP method in three ethnic groups including 14 different populations. A series of amino acid-substituted DNase 1L2 corresponding to each SNP was expressed, and its activity was measured. All of the six non-synonymous SNPs exhibited a mono-allelic distribution, whereas the distribution of some SNPs other than exonic ones was ethnicity-dependent. Each of the minor alleles in SNPs, p.Ala20Asp, p.Val104Leu, p.Asp197Ala, p.Glu274Lys and p.Asp287Asn, among the non-synonymous SNPs produced low or no activity-harbouring DNase 1L2. DNase 1L2 is well conserved, retaining full levels of enzymatic activity, with regard to these exonic SNPs in human populations. It seems plausible to assume that these SNPs affecting the activity may be one of the factors responsible for a genetic pre-disposition for failure of differentiation-associated cell death in various keratinocyte lineages, thereby leading to the development of parakeratosis. Our results may have clinical implications in relation to the pathogenesis of parakeratosis.

Seven nonsynonymous SNPs in the gene encoding human deoxyribonuclease II may serve as a functional SNP potentially implicated in autoimmune dysfunction.

Many nonsynonymous SNPs in the human DNase II gene (DNASE2), potentially relevant to autoimmunity in conditions such as rheumatoid arthritis, have been identified, but only limited population data are available and no studies have evaluated whether such SNPs are functional. Genotyping of all the 15 nonsynonymous human DNase II SNPs was performed in three ethnic groups including 16 different populations using the PCR-restriction fragment length polymorphism technique. A series of constructs corresponding to each SNP was examined. Fifteen nonsynonymous SNPs in the gene, except for p.Val206Ile in a Korean population, exhibited a mono-allelic distribution in all of the populations. On the basis of alterations in the activity levels resulting from the corresponding amino acid substitutions, four activity-abolishing and five activity-reducing SNPs were confirmed to be functional. The amino acid residues in activity-abolishing SNPs were conserved in animal DNase II. All the nonsynonymous SNPs that affected the catalytic activity of human DNase II showed extremely low genetic heterogeneity. However, a minor allele of seven SNPs producing a loss-of-function or extremely low activity-harboring variant could serve as a genetic risk factor for autoimmune dysfunction. These functional SNPs in DNASE2 may have clinical implications in relation to the prevalence of autoimmune diseases.

Mutation of the GATA site in the erythroid cell-specific regulatory element of the ABO gene in a Bm subgroup individual.

BACKGROUND: The ABO blood group is important in blood transfusion. Recently, an erythroid cell-specific regulatory element has been identified in the first intron of ABO using luciferase reporter assays with K562 cells. The erythroid cell-specific regulatory activity of the element was dependent upon GATA-1 binding. In addition, partial deletion of Intron 1 including the element was observed in genomic DNAs obtained from 111 Bm and ABm individuals, except for one, whereas the deletion was never found among 1005 individuals with the common phenotypes. STUDY DESIGN AND METHODS: In this study, further investigation was performed to reveal the underlying mechanism responsible for reduction of B antigen expression in the exceptional Bm individual. Peptide nucleic acid-clamping polymerase chain reaction was carried out to amplify the B-related allele, followed by sequence determination. Electrophoretic mobility assays and promoter assays were performed to examine whether a nucleotide substitution reduced the binding of a transcription factor and induced loss of function of the element. RESULTS: Sequence determination revealed one point mutation of the GATA motif in the element. The electrophoretic mobility shift assays showed that the mutation abolished the binding of GATA transcription factors, and the promoter assays demonstrated complete loss of enhancer activity of the element. CONCLUSION: These observations suggest that the mutation in the GATA motif of the erythroid-specific regulatory element may diminish the binding of GATA transcription factors and down regulate transcriptional activity of the element on the B allele, leading to reduction of B antigen expression in erythroid lineage cells of the Bm individual.

Genetic and expression analysis of SNPs in the human deoxyribonuclease II: SNPs in the promoter region reduce its in vivo activity through decreased promoter activity.

Five SNPs in the human DNase II gene have been reported to be associated with rheumatoid arthritis (RA). Genotype and haplotype analysis of 14 SNPs, nine SNPs of which reported in the NCBI dbSNP database in addition to these five SNPs, was performed in healthy subjects. The enzymatic activities of the amino acid substituted DNase II corresponding to each SNP and serum DNase II in healthy Japanese, and promoter activities derived from each haplotype of the RA-related SNPs were measured. Significant correlations between genotype in each RA-related SNP and enzymatic activity levels were found; alleles associated with RA exhibited a reduction in serum DNase II activity. Furthermore, the promoter activities of each reporter construct corresponding to predominant haplotypes in three SNPs in the promoter region of the gene exhibited significant correlation with levels of serum DNase II activity. These findings indicate these three SNPs could alter the promoter activity of DNASE2, leading to a decline in DNase II activity in the serum through gene expression. Since the three SNPs in the promoter region of the DNase II gene could affect in vivo DNase II activity through reduction of the promoter activity, it is feasible to identify these SNPs susceptible to RA.

Deficiency of M-LP/Mpv17L leads to development of ß-cell hyperplasia and improved glucose tolerance via activation of the Wnt and TGF-ß pathways.

M-LP/Mpv17L is a protein that was initially identified during screening of age-dependently expressed genes in mice. We have recently demonstrated that M-LP/Mpv17L-knockout (M-LP/Mpv17L-KO) in human hepatoma cells leads to a reduction of cellular cyclic nucleotide phosphodiesterase (PDE) activity, and that in vitro-synthesized M-LP/Mpv17L possesses PDE activity. These findings suggest that M-LP/Mpv17L functions as an atypical PDE, even though it has none of the well-conserved catalytic region or other structural motifs characteristic of the PDE family. In this study, we found that M-LP/Mpv17L-KO mice developed ß-cell hyperplasia and improved glucose tolerance. Deficiency of M-LP/Mpv17L in islets from KO mice at early postnatal stages or siRNA-mediated suppression of M-LP/Mpv17L in rat insulinoma cells led to marked upregulation of lymphoid enhancer binding factor 1 (Lef1) and transcription factor 7 (Tcf7), key nuclear effectors in the Wnt signaling pathway, and some of the factors essential for the development and maintenance of ß-cells. Moreover, at the protein level, increases in the levels of phosphorylated ß-catenin and glycogen synthase kinase-3ß (GSK-3ß) were observed, indicating activation of the Wnt and TGF-ß signaling pathways. Taken together, these findings suggest that protein kinase A (PKA)-dependent phosphorylations of ß-catenin and GSK-3ß, the key mediators of the Wnt and/or TGF-ß signaling pathways, are the most upstream events triggering ß-cell hyperplasia and improved glucose tolerance caused by M-LP/Mpv17L deficiency.

Global genetic analysis of all single nucleotide polymorphisms in exons of the human deoxyribonuclease I-like 3 gene and their effect on its catalytic activity.

Deoxyribonucleases (DNases) have been suggested to be implicated in the pathophysiology of autoimmune diseases. In the DNASE1L3 gene encoding human DNase I-like 3 (DNase 1L3), a member of the DNase I family, only two non-synonymous (R178 H and R206C) single nucleotide polymorphisms (SNPs) have been examined [Ueki et al., Clin. Chim. Acta 2009, 407, 20-24]. Three other non-synonymous (G82R, K96N, and I243M) and four synonymous (S17S, T84T, R92R, and A181A) SNPs, in addition to R206C and R178H, have been identified in DNASE1L3. We investigated the distribution of all these SNPs in exons of the gene in eight Asian, three African, and three Caucasian populations worldwide using newly devised genotyping methods. SNP T84T showed polymorphism in all the populations, and R92R was polymorphic in the three African and three Caucasian populations; R206C was distributed only in Caucasian populations. In contrast, no minor allele was found in five SNPs (S17S, G82R, K96N, A181A, and I243M) in DNASE1L3. Generally, the DNase 1L3 gene shows relatively low genetic diversity with regard to exonic SNPs. When the effect of amino acid/nucleotide substitutions resulting from the SNPs on DNase 1L3 activity was examined, none of the synonymous SNPs had any effect on the DNase 1L3 activity, whereas among non-synonymous SNPs, SNP G82R diminished the activity of the enzyme, being similar to R206C. These findings permit us to assume that, although only R206 exhibits polymorphisms in a Caucasian-specific manner, at least SNPs G82R and R206C in DNASE1L3 might be potential risk factors for autoimmune disease.

Confirmation that SNPs in the high mobility group-A2 gene (HMGA2) are associated with adult height in the Japanese population; wide-ranging population survey of height-related SNPs in HMGA2.

Adult height is a highly heritable trait in that multiple genes are involved. Recent genome-wide association studies have identified a novel single-nucleotide polymorphism (SNP) rs1042725 in the high mobility group-A2 gene (HMGA2) and shown it to be associated with human height in Caucasian populations. We performed a replication study to examine the associations between SNPs in HMGA2 and adult height in the Japanese population based on autopsy cases. Although we could not confirm a significant association between rs1042725 in HMGA2 and adult height, another SNP, rs7968902, in the gene achieved significance for its association in the same populations, and the effect was the same as that documented previously. These findings permit us to conclude that the SNPs in HMGA2 are common variants influencing human height across different populations. Moreover, a worldwide population study of these SNPs using 14 different populations including Asians, Africans and Caucasians demonstrated that both haplotypes and genotypes for three height-related SNPs (rs1042725, rs7968682 and rs7968902) in HMGA2 were distributed in an ethnicity-dependent manner. This information will be useful for clarifying the genetic basis of human height.

Polymorphic trial in oxidative damage of arsenic exposed Vietnamese.

Arsenic causes DNA damage and changes the cellular capacity for DNA repair. Genes in the base excision repair (BER) pathway influence the generation and repair of oxidative lesions. Single nucleotide polymorphisms (SNPs) in human 8-oxoguanine DNA glycosylase (hOGG1) Ser326Cys; apurinic/apyrimidinic endonuclease (APE1) Asp148Glu; X-ray and repair and cross-complementing group 1 (XRCC1) Arg280His and Arg399Gln in the BER genes were analyzed, and the relationship between these 4 SNPs and the urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations of 100 Vietnamese population exposed to arsenic was investigated. Individuals with hOGG1 326Cys/Cys showed significantly higher urinary 8-OHdG concentrations than did those with 326 Ser/Cys and Ser/Ser. As for APE1 Asp148Glu, heterozygous subjects showed significantly higher urinary 8-OHdG concentrations than did those homozygous for Asp/Asp. Moreover, global ethnic comparison of the allelic frequencies of the 4SNPs was performed in 10 population and previous reported data. The mutant allele frequencies of hOGG1 Ser326Cys in the Asian populations were higher than those in the African and Caucasian populations. As for APE1 Asp148Glu, Caucasians showed higher mutant frequencies than those shown by African and Asian populations. Among Asian populations, the Bangladeshi population showed relatively higher mutant allele frequencies of the APE1 Asp148Glu polymorphism. This study is the first to demonstrate the existence of genetic heterogeneity in a worldwide distribution of SNPs (hOGG1 Ser326Cys, APE1 Asp148Glu, XRCC1 Arg280His, and XRCC1 Arg399Gln) in the BER genes.

Rapid measurement of deoxyribonuclease I activity with the use of microchip electrophoresis based on DNA degradation.

Deoxyribonuclease I (DNase I) activity in serum has been shown to be a novel diagnostic marker for the early detection of acute myocardial infarction (AMI). However, the conventional method to measure DNase I activity is time-consuming. In the current study, to develop a rapid assay method for DNase I activity for clinical purposes, a microchip electrophoresis device was used to measure DNase I activity. Because DNase I is an endonuclease that degrades double-stranded DNA endo-nucleolytically to produce oligonucleotides, degradation of the DNA standard caused by DNase I action was detected using microchip electrophoresis. We detected DNase I activity within 10 min. This is the first study to apply microchip electrophoresis for the detection of DNase I activity; furthermore, it seems plausible that reduction of analysis time for DNase I activity could make this novel assay method using microchip electrophoresis applicable in clinical use.

First survey of the three gene polymorphisms (PON1 Q192R, eNOS E298D and eNOS C-786T) potentially associated with coronary artery spasm in African populations and comparison with worldwide data.

Three polymorphisms, Paraoxonase 1 (PON1) Q192R (C/G), endothelial nitric oxide synthase (eNOS) E298D (G/T) and eNOS T-786C have been suggested to be potentially associated with coronary artery spasm in Japanese patients. Data on worldwide populations are needed to clarify whether these associations could hold true for other populations. However, few data are available especially in Africans, spasm of which has been suggested to be an aetiology of myocardial infarction. Therefore, these polymorphisms were investigated in three Africans, Ovambos (n = 123), Ghanians (n = 118) and Xhosas (n = 96), together with Japanese (n = 96), by using polymerase chain reaction-restriction fragment length polymorphism analysis. Genotype-distributions of all these SNPs in African populations were significantly different from those in Caucasians, whereas were similar to those in Japanese population. African populations exhibit relatively higher frequency of spasm-associated G192 allele in PON1 Q192R being similar to Japanese population, however frequencies of spasm-associated T298 allele and -C786 allele in SNP eNOS E298D and T-786C, respectively, were conversely lower in Africans than Caucasians. Although healthy subjects have been recruited in this study, these findings may provide genetic background for elucidation of aetiology of spasm.

Genetic variants associated with arsenic metabolism within human arsenic (+3 oxidation state) methyltransferase show wide variation across multiple populations.

Human arsenic (+3 oxidation state) methyltransferase (AS3MT) is known to catalyze the methylation of arsenite. The objective of this study was to investigate the diversity of the AS3MT gene in Mexican and German populations. The distribution of 18 single nucleotide polymorphisms (SNPs) in AS3MT was assessed on healthy individuals: 38 Mestizo, 69 Nahuas, 50 Huicholes, and 32 Germans. All 18 SNPs were polymorphic in the German and Mexican populations. Of the three Mexican populations, a minor allele frequency was the highest in the Mestizo, followed by the Nahuas and Huicholes. In the German and three Mexican groups, haplotype #1(TATAGAAGTCTTCATGAC) was the most predominant. Seven haplotypes were newly found in the German and three Mexican populations. The D' values between SNP pairs were high in the German and Nahua populations; they had a similar pattern. The pattern of the Mestizo was more similar to the African than to the other Mexican populations. Huicholes had a moderate pattern of the African and German/Nahua populations. The network had three clusters. One originated in the African population and another may have originated in an Asian (Chinese and/or Japanese) population. The third one may have originated among Caucasians. This study is the first to demonstrate the existence of genetic heterogeneity in the distribution of 18 SNPs in AS3MT of German and Mexican populations.

High-fat diets cause insulin resistance despite an increase in muscle mitochondria.

It has been hypothesized that insulin resistance is mediated by a deficiency of mitochondria in skeletal muscle. In keeping with this hypothesis, high-fat diets that cause insulin resistance have been reported to result in a decrease in muscle mitochondria. In contrast, we found that feeding rats high-fat diets that cause muscle insulin resistance results in a concomitant gradual increase in muscle mitochondria. This adaptation appears to be mediated by activation of peroxisome proliferator-activated receptor (PPAR)delta by fatty acids, which results in a gradual, posttranscriptionally regulated increase in PPAR gamma coactivator 1alpha (PGC-1alpha) protein expression. Similarly, overexpression of PPARdelta results in a large increase in PGC-1alpha protein in the absence of any increase in PGC-1alpha mRNA. We interpret our findings as evidence that raising free fatty acids results in an increase in mitochondria by activating PPARdelta, which mediates a posttranscriptional increase in PGC-1alpha. Our findings argue against the concept that insulin resistance is mediated by a deficiency of muscle mitochondria.

Genetic and expression analysis of all non-synonymous single nucleotide polymorphisms in the human deoxyribonuclease I-like 1 and 2 genes.

Members of the human DNase I family, DNase I-like 1 and 2 (DNases 1L1 and 1L2), with physiological role(s) other than those of DNase I, possess three and one non-synonymous SNPs in the genes, respectively. However, only limited population data are available, and the effect of these SNPs on the catalytic activity of the enzyme remains unknown. Genotyping of all the non-synonymous SNPs was performed in three ethnic groups including six different populations using the PCR-RFLP method newly developed. Asian and African groups including Japanese, Koreans, Ghanaians and Ovambos were typed as a single genotype at each SNP, but polymorphism at only SNP V122I in DNase 1L1 was found in Caucasian groups including Germans and Turks; thus a Caucasian-specific allele was identified. The DNase 1L1 and 1L2 genes show relatively low genetic diversity with regard to these non-synonymous SNPs. The level of activity derived from the V122I, Q170H and D227A substituted DNase 1L1 corresponding to SNPs was similar to that of the wild-type, whereas replacement of the Asp residue at position 197 in the DNase 1L2 protein with Ala, corresponding to SNP D197A, reduced its activity greatly. Thus, SNP V122I in DNase 1L1 exhibiting polymorphism exerts no effect on the catalytic activity, and furthermore SNP D197A in DNase 1L2, affecting its catalytic activity, shows no polymorphism. These findings permit us to postulate that the non-synonymous SNPs identified in the DNase 1L1 and 1L2 genes may exert no influence on the activity levels of DNases 1L1 and 1L2 in human populations.

Global analysis of single nucleotide polymorphisms in the exons of human deoxyribonuclease I-like 1 and 2 genes.

Several SNPs in the deoxyribonuclease I-like 1 (DNase 1L1) and DNase 1L2 were investigated. In the present study, the genotype distributions of three synonymous SNPs (V59V, rs1050095; P67P, rs1130929; A277A, rs17849495) in the DNase 1L1 gene and four non-synonymous SNPs, V122I (rs34952165), Q170H (rs6643670), and D227A (rs5987256) in the DNase 1L1 gene, as well as D197A (rs62621282) in the DNase 1L2 gene were investigated in 13 populations. In all the populations, no variation was found in four SNPs (V59V, Q170H, D227A, and A277A) in DNASE1L1 or in D197A in DNASE1L2. As for V122I, only the German population showed a low degree of polymorphism. The SNP V122I in DNASE1L1 was monoallelic for the G-allele in all of the Asian and African populations examined, with no polymorphism being evident. Since the A-allele in SNP V122I was distributed in only the Caucasian populations, not in the other ethnic groups, it was confirmed that the A-allele in SNP V122I was Caucasian-specific. On the other hand, only P67P in DNASE1L1 was polymorphic among three synonymous SNPs. The effect of nucleotide substitution corresponding to polymorphic SNP P67P on DNase 1L1 activity was examined: the corresponding nucleotide substitution in polymorphic SNP P67P has little effect on the DNase activity.