Q192R polymorphism in the PON1 gene and nasal polyp in a Turkish population

The pathogenesis of nasal polyps is not completely understood. Oxidative damage contributes to polyp formation in the nasal mucosa. The paraoxonase 1 (PON1) enzyme is an important liver enzyme with high antioxidant activity. In this study, we investigated the correlation between Q192R genotypic polymorphism of the PON1 enzyme and nasal‐polyp disease. The study examined 62 nasal‐polyp patients and 88 controls. PON1 Q192R polymorphism was determined using polymerase chain reaction‐restriction fragment length polymorphism. The genotype distribution of the PON1 gene was significantly different between nasal‐polyp patients (QQ = 69.35%, QR = 25.81%, RR = 4.83%) and healthy controls (QQ = 52.27%, QR = 44.31%, RR = 3.40%). Our results suggest that the PON1 QQ genotype (odds ratio [OR] = 2.066, P = .036) is associated with a higher risk of developing the nasal‐polyp disease while QR genotype (OR = 0.437, P = .021) showed a lower risk.     

A preliminary study of human paraoxonase and PON 1 L/M55–PON 1 Q/R 192 polymorphisms in Turkish patients with coronary artery disease

Paraoxonase 1 (PON 1) is a high‐density lipoprotein (HDL)‐associated enzyme with antioxidant function protecting low‐density lipoprotein (LDL) from oxidation. PON 1 has two amino acid polymorphisms in coding region; L/M 55 and Q/R 192. These polymorphisms modulate paraoxonase activity of the enzyme. PON 1 activity decreases in coronary artery disease (CAD). In the present study, distribution of PON 1 L/M 55 and Q/R 192 polymorphisms and the effect of these polymorphisms on the activities of PON 1, and on the severity of CAD in 277 CAD (+) patient and 92 CAD (?) subjects were examined. PON 1 L/M 55 and Q/R 192 genotypes were determined by PCR, RFLP and agarose gel electrophoresis techniques. Genotype distributions and allele frequencies for PON 1 Q/R 192 polymorphism were not significantly different between controls and CAD (+) patient group (p > 0.05), but in genotype and allele distribution of PON 1 L/M55 polymorphism, there was significantly difference among groups (p < 0.05). Genotype distributions for both polymorphisms were not significantly different between subgroups of single‐vessel disease (SVD), double‐vessel disease (DVD) and triple‐vessel disease (TVD). Serum PON 1 activity was lower in CAD (+) group than in controls and this was also statistically significant (p < 0.001). In both groups, the highest PON activities were detected in LL and RR genotypes. In summary, our results suggest that there is an association between the PON 1 L/M 55 polymorphism of paraoxonase and CAD in Turkish patients but not with PON 1 Q/R 192 polymorphism. However, it is hard to correlate these polymorphisms and severity of CAD. Copyright © 2009 John Wiley & Sons, Ltd.     

Paraoxonase 1 gene polymorphism 192Q/R in old men and long-livers from Tatars ethnic group

Comparison in genotype and allele frequencies of people groups of younger (from 1 till 20 years), middle (21-55 years), elderly (56-74 years), senile (75-89 years) age and long-livers (90-109 years) have been performed (only 1116 person) with the purpose of analysis of molecular-genetic bases of ageing and longevity of the person. Allele variants of PON1 gene have been identified by polymerase chain reaction in a combination with restriction analysis. In the general sample of Tatars genotypes PON1*Q/*Q, PON1*Q/*R and PON1*R/*R are revealed with frequencies of 46.15, 44.35 and 9.5%, alleles PON1*Q and PON1*R are found with frequencies of 68.32 and 31.68% accordingly. Statistically significant distinctions on frequencies of genotypes and alleles between separate age groups are found. It has appeared, that frequency of PON1*R allele (28.46%) is lowered among old men in comparison with those among persons of younger age (37.42%, P = 0.009). However essentially above in group of long-livers, than in group of old men, frequencies allele PON1*R (P = 0.005) and genotype PON1*R/*R (P = 0.01).     

Paraoxonase1, its Q192R polymorphism and HDL-cholesterol in relation to intensive cardiac care unit stay in ischemic heart disease

AIMS AND OBJECTIVES:

The present study was evaluated the atheroprotective potential of paraoxonase1 (PON1) and its Q192R polymorphism, to determine whether this polymorphism, which is responsible for differential PON1 activity plays any role in the pathogenesis, severity and extent of coronary artery disease (CAD).

MATERIALS AND METHODS:

This hospital-based cross-sectional study investigated 60 diagnosed cases of CAD and 60 age and gender matched controls. All were assessed for serum PON1 activity, PON1 Q192R polymorphism and for classical cardiovascular risk factors. Individual serum phenotyping for PON1 Q192R polymorphism was determined by double substrate hydrolysis assay. Severity of CAD was assessed by the length of intensive cardiac care unit (ICCU) stay.

RESULTS:

Serum PON1 activity is significantly reduced in cases of CAD (92.6 ± 31.13 IU/L when compared with controls (105.26 ± 32.53 IU/L). Furthermore, serum arylesterase activity is reduced in CAD patients (90.31 ± 23.26 kU) when compared with the control subjects (101.61 ± 28.68 kU). Serum PON1 and arylesterase activities are significantly negatively correlated with the length of ICCU stay (r = −393 and r = −374 respectively). There is no significant difference in the occurrence of CAD and length of ICCU stay among the PON1 phenotypes (P = 0.92). Logistic regression analysis after adjustment of established risk factors revealed no significant association between CAD risk and PON1 Q192R polymorphism (odds ratios: 1.179 [95% confidence intervals: 0.507-2.744], P = 0.702).

SUMMARY AND CONCLUSIONS:

The current study demonstrates that the activity of the PON1 enzyme may be more important factor than the PON1 Q192R polymorphism in the severity and extent of CAD.     

The determination of Q192R polymorphism of paraoxonase 1 by using non-toxic substrate p-nitrophenylacetate

CONTEXT:

The human serum paraoxonase 1 (PON1) is calcium-dependent esterase and associates with the high density serum lipoproteins. PON1 plays a major role in oxidation of high density lipoprotein and low density lipoprotein and prevention of atherogenesis in coronary heart disease. PON1Q and R allele hydrolyses number of substrates like paraoxon (PO) (diethyl p-nitrophenyl phosphate) and phenylacetate.

AIMS:

The aim of the study is to the determination of Q192R polymorphism of PON1 by using non-toxic substrate p-nitrophenylacetate and compares it with the phenotype determined by using PO as substrate.

MATERIALS AND METHODS:

The study group consists of 60 healthy normal patients. Paraoxonase activity was measured using the procedure described by Eckerson (Reference method) and for phenotyping; the ratio of hydrolysis of PO in the presence of 1 M NaCl (salt-stimulated PON1, SALT) to the hydrolysis of phenylacetate (PA) is calculated. In new method (Haagen et al.) arylesterase activity measured using p-nitrophenylacetate and for phenotyping arylesterase, the ratio of inhibition of enzymatic hydrolysis of p-nitrophenylacetate (substrate) by phenyl acetate to non-inhibited hydrolysis of p-nitrophenylacetate (inhibited arylesterase activity (IA-IA₀)/non-inhibited arylesterase activity (NIA).

RESULTS:

It was found that paraoxonase activity is trimodally distributed in both the methods. There is no significant difference in the distribution of PON1 phenotypes of both reference method and new method being frequencies 0.946 and 0.376 respectively and there was no significant difference for phenotypic polymorphism for an individual by both methods (χ²= 0.15 and P = 0.9262).

CONCLUSION:

The Q192R polymorphism of PON1 by using non-toxic substrate p-nitrophenylacetate showed trimodal distribution of QQ (homozygous), QR (heterozygous), and RR (homozygous) phenotype and it is comparable with reference method. This method can be used for PON1 phenotype in different pathological and complex disease conditions.     

The 192R/Q polymorphs of serum paraoxonase PON1 differ in HDL binding, lipolactonase stimulation, and cholesterol efflux

Serum paraoxonase (PON1) is a HDL-associated enzyme exhibiting potentially antiatherogenic properties. Here, we examined the common PON1-192R/Q human polymorphism. Despite numerous studies, the effect of this polymorphism on the antiatherogenic potential of PON1 is yet unresolved. Our structural model suggests that amino acid 192 constitutes part of the HDL-anchoring surface and active site of PON1. Based on our findings that PON1 is an interfacially activated lipolactonase that selectively binds HDL carrying apolipoprotein A-I (apoA-I) and is thereby greatly stabilized and catalytically activated, we examined the interaction of the PON1-192 isozymes with reconstituted HDL-apoA-I particles. We found that PON1 position 192 is indeed involved in HDL binding. The PON1-192Q binds HDL with a 3-fold lower affinity than the R isozyme and consequently exhibits significantly reduced stability, lipolactonase activity, and macrophage cholesterol efflux. We also observed the lower affinity and stability of the 192Q versus the 192R isozyme in sera of individuals belonging to the corresponding genotypes. The observed differences in the properties of PON1-192R/Q isozymes provide a basis for further analysis of the contribution of the 192R/Q polymorphism to the susceptibility to atherosclerosis, although other factors, such as the overall levels of PON1, may play a more significant role.     

Polymorphism of the apolipoprotein E gene and risk of multiple sclerosis in ethnic Russians

Multiple sclerosis (MS) is a multifactorial disease of the central nervous system with pronounced hereditary predisposition. The purpose of the study was to test the assumption on the involvement of the apolipoprotein E gene (APOE) polymorphism in exon 4 in the development of MS in ethnic Russians. Samples independently collected in Moscow (106 MS cases and 189 control healthy volunteers), Sverdlovsk oblast (54 and 109, respectively), and the Republic of Bashkortostan (119 and 285, respectively) were examined. Genotypes for 2059C/T and 2197C/T polymorphisms of the APOE gene, which determine the amino acid substitutions C112R and R158C in apolipoprotein E, were analyzed by polymerase chain reaction followed by restriction analysis of amplificates. No statistically significant differences in genotype or allele frequencies were found between the control group and the group of MS cases. The APOE*4 allele is not associated with the risk of MS in ethnic Russians.     

Paraoxonase 1 gene polymorphisms, paraoxonase/arylesterase activities and oxidized low-density lipoprotein levels in patients with migraine

The vascular endothelial dysfunction has been implicated in the pathogenesis of migraine. Oxidized low‐density lipoprotein (ox‐LDL) may impair endothelial function. Paraoxonase‐1 (PON‐1) prevents oxidative modification of LDL cholesterol (LDL‐C). So we investigated serum PON‐1 and arylesterase (ARE) activities, PON‐1 55 L/M and 192Q/R polymorphisms and the serum lipid profile in patients with migraine. Biochemical parameters and PON‐1 polymorphism analyses were assessed in 104 patients with migraine and 86 healthy subjects. Ox‐LDL was detected by ELISA, and polymorphisms were determined using PCR–restriction fragment length polymorphism analysis. Patients with migraine had lower PON‐1 and ARE activities (p < 0·001, for both) and higher ox‐LDL and LDL‐C levels (p < 0·001, for both) and ox‐LDL: LDL‐C ratio (p < 0·005) than the controls. The genotype distribution and the allele frequencies for PON‐1 55 L/M and 192Q/R polymorphisms were not different among the study populations. The results of our current study indicate that migrainous patients have decreased serum PON‐1 and ARE activities and increased serum ox‐LDL levels, which may have a clinical importance in the treatment of migraine. Copyright © 2011 John Wiley & Sons, Ltd.     

Relationship between the paraoxonase (PON1) L55M and Q192R polymorphisms and obesity in a Mexican population: a pilot study

The aim of this study was to examine the relationship between the L55M and Q192R paraoxonase (PON1) polymorphisms and obesity in a population of adult Mexican workers. The study population included 127 adult individuals from the Universidad Autónoma del Estado de Morelos, ranging in age from 20 to 56 years and representing both sexes. Based on body mass index, 63 individuals were classified as obese and 64 as normal weight. The PON1-Q192R and PON1-L55M polymorphisms were determined by restriction fragment length polymorphism PCR analysis. Both arylesterase and paraoxonase activity levels were similar in both groups, whereas systolic pressure, triglyceride, total cholesterol, low-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, glucose, and insulin levels were higher in the obese group than in the normal-weight group (P < 0.05). An exception was the high-density lipoprotein cholesterol (HDL-C) levels, which were lower in the obese group (P < 0.05). Although the PON1-Q192R polymorphism was not associated with either group, the frequency of the homozygous L genotype for the PON1-L55M polymorphism was higher in the obese group than in the normal-weight group (P < 0.05). In conclusion, this study established a positive association between the PON1-L55M homozygous L genotype and obesity.     

Association between paraoxonase-1 gene Q192R and L55M polymorphisms and risk of gastric cancer: A case-control study from Iran

The aim of the present study was to examine the relation between two paraoxonase1 (PON1) polymorphisms, Q192R and L55M and susceptibility to gastric cancer in an Iranian population. In this case-control study the PON1 polymorphisms were assessed in 90 gastric cancer patients and 90 healthy controls by polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) method. Regarding PON1 Q192R polymorphism, a significant increase in the R allele in the patient group compared with the controls (p value?=?0.0006) While the Q allele was more frequent in the control group. No significant difference was found in the genotype or allele frequency of the L55M polymorphism between healthy individuals and patients with gastric cancer. Our results demonstrated the protective effect of Q allele against gastric cancer.     

Polymorphism C3435T of the MDR1 gene in Central Americans and Spaniards

The human multidrug resistance gene (MDR1) encodes for P-glycoprotein (P-gp) which is a transmembrane transporter protein that acts as an efflux pump for a number of lypophilic compounds. It plays a protective role for cells against DNA damage. The wobble C3435T polymorphism at exon 26 has been associated with different expression levels and activity. Differences in allele frequency of the C3435T polymorphism have been demonstrated between distinct ethnic groups. In our study we examined these polymorphisms in 433 healthy individuals. From these, 229 were Central American mestizos from Nicaragua (n = 117) and El Salvador (n = 112) to be compared with a group of 204 North Spaniards, with the aim of detecting potential genotypic differences between these populations. The genotypes were determined by PCR-RFLP. The frequencies of the C allele were very similar among Central Americans (0.53) and Spaniards (0.52), which is consistent with the ethnic origin of Central American individuals (Amerindians and European Caucasians). In comparison to other previously studied populations, the C allele frequency in Central Americans was significantly lower than that found in African populations and higher than that observed in the Indian and Southwest Asian populations. These data may be relevant for dose recommendation of P-gp substrate drugs and also for studies of allele disease association in the Central American population.     

Arylesterase activity of paraoxonase 1 (PON1) on HDL3 and HDL2: Relationship with Q192R,C-108T,and L55M polymorphisms

BackgroundControversy exists regarding the role of the subfractions of high-density lipoproteins (HDL₂ and HDL₃) in cardiovascular disease. The functionality of these particles, and their protective role, is due in part to the paraoxonase 1 (PON1) presence in them. The polymorphisms rs662 (Q192R, A/G), rs854560 (L55 M, T/A), and rs705379 (C-108T) of the PON1 gene have been related to enzyme activity and, with the anti-oxidative capacity of the HDL. The objective was to determine the arylesterase PON1 activity in HDL₃ and HDL₂ and its relationship with the polymorphisms mentioned, in a young population.MethodsThe polymorphisms were determined through mini-sequencing (SnaPshot). The HDL subpopulations were separated via ionic precipitation, cholesterol was measured with enzymatic methods, and PON1 activity was measured through spectrophotometry.ResultsThe results show that the PON1 polymorphisms do not influence the cholesterol in the HDL. A variation between 40.02 and 43.9 mg/dL was in all the polymorphisms without significant differences. Additionally, PON1 activity in the HDL₃ subfractions was greater (62.83 ± 20 kU/L) than with HDL₂ (35.8 ± 20.8 kU/L) in the whole population and in all the polymorphisms (p < 0.001), and it was independent of the polymorphism and differential arylesterase activity in the Q192R polymorphism (QQ > QR > RR). Thus, 115.90 ± 30.7, 88.78 ± 21.3, 65.29 ± 10.2, respectively, for total HDL, with identical behavior for HDL₃ and HDL₂.ConclusionsPON1 polymorphisms do not influence the HDL_-c, and the PON activity is greater in the HDL₃ than in the HDL₂, independent of the polymorphism, but it is necessary to delve into the functionality of these findings in different populations.     

Paraoxonase activity against nerve gases measured by capillary electrophoresis and characterization of human serum paraoxonase (PON1) polymorphism in the coding region (Q192R)

An analytical method for determining paraoxonase activity against sarin, soman and VX was established. We used capillary electrophoresis to measure directly the hydrolysis products: alkyl methylphosphonates. After enzymatic reaction of human serum paraoxonase (PON1) with nerve gas, substrate was removed with dichloromethane, and alkyl methylphoshphonates were quantified by capillary electrophoresis of reversed osmotic flow using cationic detergent and sorbic acid. This method was applied to the characterization of human serum PON1 polymorphism for nerve gas hydrolytic activity in the coding region (Q192R). PON1-192 and PON1-55 genotypes were determined by their gel electrophoretic fragmentation pattern with restriction enzymes after polymerase chain reaction (PCR) of blood leukocyte genomic DNA. Frequencies of genotypes among 63 members of our institutes with PON1-192 and PON1-55 were 9.5% (¹⁹²QQ), 30.1% (¹⁹²QR) and 44.4% (¹⁹²RR), and 82.5% (⁵⁵LL), 17.5% (⁵⁵LM) and 0% (⁵⁵MM), respectively. ¹⁹²Q and ¹⁹²R enzymes were purified from the respective genotype human plasma, using blue agarose affinity chromatography and diethyl amino ethane (DEAE) anion exchange chromatography. V_max and K_m were measured using Lineweaver-Burk plots for hydrolytic activities against sarin, soman and VX at pH 7.4 and 25 °C. For sarin and soman, the V_max for ¹⁹²Q PON1 were 3.5- and 1.5-fold higher than those for ¹⁹²R PON1; and k_cat/K_m for ¹⁹²Q PON1 were 1.3- and 2.8-fold higher than those for ¹⁹²R PON1. For VX, there was little difference in V_max and k_cat/K_m between ¹⁹²Q and ¹⁹²R PON1, and VX hydrolyzing activity was significantly lower than those for sarin and soman. PON1 hydrolyzed sarin and soman more effectively than paraoxon.     

Polymorphism A/G in Position +49 of CTLA4 Exon 1 in Multiple Sclerosis in Russians

The association of multiple sclerosis (MS) with alleles A and G of the cytotoxic T-lymphocyte antigen 4 (CTLA4) gene, a candidate gene for autoimmune disorders, was studied. The allele polymorhism results from single nucleotide substitution (A/G) in position +49 of exon 1 and leads to substitution Thr Ala in the leader peptide. The case–control study involved two groups of ethnic Russians: 168 MS patients and 209 healthy subjects from central Russia. Genotype frequencies were in agreement with the Hardy–Weinberg equilibrium in both groups (P > 0.05). The controls significantly differed in CTLA4 allele and genotype frequencies from Mongoloids but not from other Caucasians. No association was observed between MS and CTLA4. In addition, the combined association with MS was analyzed for both the CTLA4 alleles and allele groups of HLA DRB1. The results showed that the CTLA4 dimorphism does not affect susceptibility to MS in ethnic Russians, be these stratified or not with regard to DRB1 alleles corresponding to serologic specificities DR1 to DR16.     

Polymorphism of SLC14A1 encoding human erythrocytic Kidd antigens in the Chinese population

The SLC14A1 gene, which encodes the important Kidd blood group antigens, has not been systematically?analyzed at the molecular level in Chinese individuals. In this study, SLC14A1 genetic polymorphism was examined in Chinese individuals with Jk(a+b-), Jk(a+b+), and Jk(a-b+) expression. The Kidd phenotype was determined for 146 specimens using monoclonal anti-Jk^a and -Jk^b antibodies. From these, 87 specimens were Jk(a-b+), 21 were Jk(a+b-), and 38 were Jk(a+b+). According to the Kidd phenotype results, 20 specimens were randomly selected from each group, i.e., Jk(a-b+), Jk(a+b-), and Jk(a+b+), for the molecular analyses of exons 3 to 11 of the SLC14A1 gene. Novel alleles were detected in the SLC14A1 gene, including IVS3-106A, IVS3-99A, exon3 130G, IVS4-299G, IVS4-293G, IVS4+211C, IVS4 +230C, exon6 499A, exon6 588A, IVS7-68T, IVS9+244G, and IVS10-153T, indicating that the locus harbored significant polymorphism. We also showed that IVS4-299, IVS7-68, and IVS10-153 were novel SNPs absolutely associated with exon 8 nt. 838. The minor allele frequencies were all greater than 10% and all SNPs in the Chinese population showed Vel antigen expression on RBC membranes. We identified 12 SNPs in the SLC14A1 gene in the Chinese population, IVS3-106A, IVS3-99A, exon3 130G, IVS4-299G, IVS4-293G, IVS4+211C, IVS4 +230C, exon6 499A, exon6 588A, IVS7-68T, IVS9+244G, and IVS10-153T. Our results also indicated that three novel SNPs produced Jk^a and Jk^b antigens in Chinese individuals.     

Two- and three-locus haplotypes of the paraoxonase (PON1) gene are associated with coronary artery disease in Asian Indians

Introduction

In view of the reported association of SNPs in the paraoxonase (PON1) gene with coronary artery disease (CAD), and the absence of conclusive data from India, we investigated the relationship of three SNPs at different loci (‐108C/T, L55M and Q192R) of the PON1 gene and their haplotypes with CAD among people residing in the northern plains of India.

Materials and methods

One hundred and seventy-eight healthy controls and two hundred and four angiographically-proven CAD patients were genotyped using PCR-RFLP.

Results

Of the three SNPs, only the R allele of Q192R polymorphism was associated with CAD (p < 0.05). Two locus haplotypes QT (OR 0.55, p = 0.0004, 95% CI 0.39–0.77, significant) and LQ (odds ratio 0.73, p = 0.03, 95% CI 0.55–0.97, trend) showed protective effects, while haplotypes MR (OR = 5.36, p = 0.0001, 95% CI 2.045–14.049) and MC (OR = 2.71, p = 0.011, 95% CI 1.221–6.046) were associated with increased risk of CAD. MRT, a minor three-locus haplotype also displayed significant association (OR 4.93, 95% CI 1.7–13.5) with the disease. Significance was assessed after applying Bonferroni's correction.

Conclusions

Our study revealed that only one SNP at a single locus but several haplotype combinations of PON1 coding and promoter-region polymorphisms were associated with the risk of or protection against CAD. Thus, haplotype analysis brought better insights into the association of PON1 gene polymorphisms with CAD in Asian Indians.     

The Q192R polymorphism of the paraoxonase 1 gene is a risk factor for coronary artery disease in Saudi subjects

Paraoxonase-1 (PON1) is a HDL-bound antioxidant enzyme that protects LDL from oxidative modification. Discovery of the antioxidant properties of PON1 led to extensive research on its role in the initiation and progression of atherosclerosis. The Q192R (rs662; A/G) polymorphism, which results in the glutamine to arginine substitution at position 192, of the PON1 gene has been linked to increased atherosclerosis risk in several but not all population studies. Besides genetic factors, environmental variables and ethnicity have been implicated as factors responsible for the ambiguity in relating the PON1 gene with atherosclerotic risk. Here, we tested the association of the Q192R polymorphism with coronary artery disease (CAD) in Saudi ethnic subjects taking environmental factors into consideration. The genomic DNA samples from 121 angiographically confirmed CAD cases and 108 normal healthy control subjects were genotyped by PCR–RFLP analysis. The distribution of QQ, QR, and RR genotypes was significantly different between cases and controls (p < 0.005). The RR genotype was associated with CAD risk independently of several established risk factors including age, gender, smoking, obesity, and diabetes (OR 2.2, 1.4–7.4, p < 0.01). Genotype-based stratification of demographic and biochemical data revealed that the RR genotype has proatherogenic properties. This study, thus, identifies the Q192R polymorphism as an additional risk factor for CAD in the Saudi population and suggests that it may have prognostic value. The negative effect of this genetic variant is presumably due to the diminished ability of the RR variant genotype of PON1 to blunt LDL oxidation.     

Ethnic variations of a retinoblastoma susceptibility gene (RB1) polymorphism in eight Asian populations

An A → G single nucleotide polymorphism (SNP) at nucleotide 153,104 in the retinoblastoma susceptibility locus (RB1) at 13q14 was previously reported to be present only in Asians. In this study, we determined the distribution of this SNP in normal Southeast Asian populations (Chinese, Malay, Javanese, Thai, Filipino), in South Asian populations (Bangladeshi, Pakistani Pushtun and Indian) and in Chinese retinoblastoma cases and control subjects. TheRB1 SNP was present in all populations at an overall frequency of ≤0.18. Heterozygosity was higher in the Southeast Asian groups (0.14–0.34) than in the South Asian groups (Bangladeshi and Indian) (0.04–0.06). Significant differences in allele frequencies were found between the two population groups. Interestingly, our Pakistani population comprised of ethnic Pushtuns from northwest Pakistan was significantly different from the neighbouring Bangladeshi and Indian populations. No significant difference was found between Chinese case patients and control subjects. ThisRB1 SNP appears to be an ethnic variant prevalent in Southeast Asian populations and may be useful for studyingRB1 inheritance by pedigree analysis.     

Pigmentation in Black-boned sheep (Ovis aries): association with polymorphism of the MC1R gene

Variations in vertebrate skin and hair color are due to varied amounts of eumelanin (brown/black) and phaeomelanin (red/yellow) produced by the melanocytes. The melanocortin 1 receptor (MC1R) is a regulator of eumelanin and phaeomelanin production in the melanocytes, and MC1R mutations causing coat color changes are known in many vertebrates. We have sequenced the entire coding region of the MC1R gene in Black-boned, Nanping indigenous and Romney Marsh sheep populations and found two silent mutation sites of A12G and G144C, respectively. PCR-RFLP of G144C showed that frequency of allele G in Black-boned, Nanping indigenous and Romney Marsh sheep was 0.818, 0.894 and 0, respectively. Sheep with GG genotype had significantly higher (P < 0.05) tyrosinase activity than sheep with CC genotype in the all investigated samples. Moreover, there was significant effect of MC1R genotype on coat color, suggesting that MC1R gene could affect coat color but not black traits. There would be merit in further studies using molecular techniques to elucidate the cause of black traits in these Black-boned sheep.