ABSTRACT
BACKGROUND: Lactase persistence is an autosomal dominant trait commonly distributed in Europe as well as some parts of east Africa and the Arabian Peninsula. Using real-time PCR to detect the -13910C > T variant common in the European population is a reliable analysis although other variants in the probe-binding site may cause errors in analysis. The aim of this study was to determine the prevalence of the variants in a Danish cohort examined for lactose intolerance as well as to improve the real-time PCR analysis for detection of the different variants. METHODS: We genotyped 3395 routine samples using real-time PCR for the -13910C > T-variant. All consecutive samples identified as -13910CC were sequenced using Sanger Sequencing. Using the SDS software we examined various quality value settings to improve on the genetic analysis. RESULTS: Using real-time PCR resulted in 100% successful genotyping of the -13910C > T variant. By using a quality value of 99% and sequencing the undetermined samples we improved the ability of the assay to identify variants other than -13910C > T. This resulted in a reduction of the diagnostic error rate by a factor of 2.4 while increasing the expenses only 3%. CONCLUSIONS: We conclude that using a quality value of 99% in the SDS software significantly improves the diagnostic efficiency of the real-time PCR assay for detecting variants associated to lactase persistence.
Subject(s)
Lactase/genetics , Lactose Intolerance/diagnosis , Lactose Intolerance/genetics , Polymorphism, Single Nucleotide , Promoter Regions, Genetic , Alleles , Denmark/epidemiology , Gene Expression , Gene Frequency , Genetic Testing , Genotype , Humans , Lactase/deficiency , Lactose Intolerance/epidemiology , Lactose Intolerance/physiopathology , Phenotype , Prevalence , Real-Time Polymerase Chain Reaction , Sequence Analysis, DNA , SoftwareABSTRACT
INTRODUCTION: In this study, we hypothesised that the genotypes coding for low antioxidative enzyme activity are associated with asthma and reduced lung function. METHODS: Using the European Community Respiratory Health Survey protocol, we enlisted 1091 Danish subjects in this cross-sectional study. Asthma phenotypes were defined as asthma symptoms in combination with steroid usage, bronchial hyperresponsiveness and atopy. These phenotypes and lung function were analysed with respect to glutathione peroxidase, GPX1 (Pro198Leu, rs1050450), manganese superoxide dismutase, SOD2 (Ala16Val, rs4880) and three glutathione S-transferases; GSTP1 (Ile105Val, rs1695), GSTT1 (gene copy number) and GSTM1 (gene copy number). RESULTS: We found no associations between these genotypes and the asthma phenotypes. For the 201 subjects identified as current smokers and recruited via random sampling, an association was seen between increasing number of genotypes coding for high antioxidative enzyme activity (GPX1 Pro/Pro, SOD2 Val/Val, GSTP1 Ile/Ile, GSTT1 two copies, GSTM1 two copies) and forced expiratory volume in 1 s (FEV1%) predicted. The increase in FEV1% predicted was 2.0% (95% confidence interval 0.3-3.8) per genotype. There was no identified significance for the inverse association between FEV1% predicted and number of genotypes coding for low antioxidative enzyme activity. CONCLUSION: The present study does not support the hypothesis that asthma is associated with genotypes of these major antioxidative enzymes. However, we speculate that since we see an impact of these genotypes on lung function in young adult smokers, polymorphisms in antioxidative enzymes may contribute to the range of susceptibility of smokers have to Chronic obstructive lung disease.
Subject(s)
Asthma/genetics , Forced Expiratory Volume/genetics , Polymorphism, Genetic , Smoking/genetics , Adult , Cross-Sectional Studies , Female , Genotype , Glutathione Peroxidase/genetics , Glutathione Transferase/genetics , Humans , Linear Models , Male , Phenotype , Superoxide Dismutase/genetics , Glutathione Peroxidase GPX1ABSTRACT
OBJECTIVE: Glutathione peroxidase 1 (GPX1) is one of the major oxidative enzymes. Our aim was to characterize factors influencing its activity and to determine whether or not the activity is associated with asthma. MATERIAL AND METHODS: Serum selenium concentration was measured, GPX1 polymorphisms were genotyped and smoking history was obtained in a Danish population-derived case-base cohort of 1,191 subjects designed to evaluate risk factors for asthma. GPX1 activity was measured in 134 male and 164 female subjects equally distributed according to genotype of GPX1. Among these subjects, 82 (28 %) had doctor-diagnosed asthma. RESULTS: The average serum selenium concentration was too low for optimal enzyme activity (mean (SE), 83.4 (0.76) ng/mL). GPX1 activity in men was lower than in women, 52.6 (0.66) and 56.4 (0.59) U/g protein, respectively (p<0.001). In men, activity was positively associated with serum selenium concentration (p = 0.005) and negatively associated with both active smoking (p = 0.009) and exposure to environmental tobacco smoke (p = 0.02). In women, activity was associated with genotypes with 59.2 (1.4), 56.0 (1.4) and 54.2 (1.4) U/g protein in the homozygote wild-type, the heterozygote and the homozygote variant type, respectively (p = 0.001). Doctor-diagnosed asthma was unrelated to GPX1 activity in either sex. CONCLUSION: Determinants for activity in the oxidative enzyme GPX1 show marked differences between the sexes, but the activity is not associated with asthma. Sex ought to be taken into consideration when analysing the activity of the enzyme.
