Haplotype analysis of the low density lipoprotein receptor (LDLR) gene was performed in Norwegian subjects heterozygous for familial hypercholesterolemia (FH). Southern blot analysis of genomic DNA, using an exon 18 specific probe and the restriction enzyme NcoI, showed that two out of 57 unrelated FH subjects had an abnormal 3.6 kb band. Further analyses revealed that this abnormal band was due to a 9.6 kb deletion that included exons 16 and 17. The 5' deletion breakpoint was after 245 bp of intron 15, and the 3' deletion breakpoint was in exon 18 after nucleotide 3390 of cDNA. Thus, both the membrane-spanning and cytoplasmatic domains of the receptor had been deleted. A polymerase chain reaction (PCR) method was developed to identify this deletion among other Norwegian FH subjects. As a result of this screening one additional subject was found out of 124 subjects screened. Thus, three out of 181 (1.7%) unrelated Norwegian FH subject possessed this deletion. The deletion was found on the same haplotype in the three unrelated subjects, suggesting a common mutagenic event. The deletion is identical to a deletion (FH-Helsinki) that is very common among Finnish FH subjects. However, it is not yet known whether the mutations evolved separately in the two countries.
Recently, two G-->A polymorphisms at positions -308 and -238, in the promoter of the tumor necrosis factor alpha (TNF-alpha) gene, have been identified. These variants have, in different ethnic groups, been linked to estimates of insulin resistance and obesity. The objective of the present study was to investigate whether these genetic variants of TNF-alpha were associated with features of the insulin resistance syndrome or alterations in birth weight in two Danish study populations comprising 380 unrelated young healthy subjects and 249 glucose-tolerant relatives of type 2 diabetic patients, respectively. All study participants underwent an iv glucose tolerance test with the addition of tolbutamide after 20 min. In addition, a number of biochemical and anthropometric measures were performed on each subject. The subjects were genotyped for the polymorphisms by applying PCR restriction fragment length polymorphism. Neither of the variants was related to altered insulin sensitivity index or other features of the insulin resistance syndrome (body mass index, waist to hip ratio, fat mass, fasting serum lipids or fasting serum insulin or C-peptide). Birth weight and the ponderal index were also not associated with the polymorphisms. In conclusion, although the study was carried out on sufficiently large study samples, the study does not support a major role of the -308 or -238 substitutions of the TNF-alpha gene in the pathogenesis of insulin resistance or altered birth weight among Danish Caucasian subjects.
The A1 allele of TaqI A restriction fragment length polymorphism (RFLP) in the D2 receptor (DRD2) gene locus has been suggested to be associated with low D2 receptor density in man. Striatal dopamine transporter (DAT) densities were studied with [(123)I]2-beta-carbometoxy-3beta(4-iodophenyl)tropane and single-photon emission tomography in 29 detoxified alcoholics, who were also genotyped for the two alleles of TaqI A RFLP at the DRD2 receptor gene locus. Alcoholics with the A1/A2 genotypes (n = 10) had statistically significantly higher DAT densities than subjects with the A2/A2 genotypes [n = 19; 8.0 +/- 1.2 (mean +/- SD) vs 6.9 +/- 1.1, P = 0.035]. We suggest that the TaqI A RFLP is in linkage disequilibrium with a gene variant modifying DAT density in alcoholics.
A retrospective study of acute hepatitis B (AHB) during 1995-1996 in G?teborg, Sweden, was carried out to investigate whether the increasing number of hepatitis B virus (HBV) carriers due to immigration in northwestern Europe has influenced the incidence or genotype heterogenicity. 24 cases of AHB were identified, the probable transmission route of which was intravenous drug use (IVDU) in 11 (46%), heterosexual in six (25%), homosexual in one, hemodialysis in two and unknown in four cases. In no case was the source an immigrant with chronic HBV infection. Genotype D was seen in 12 patients, seven being anti-HCV-positive IVD users, two probably infected heterosexually and three with an unknown source. Genotype A was found in six patients: three IVD users, a sexual partner of an IVD user and two dialysis patients. Genotype B was found in one patient infected during travel to Vietnam, and genotype C in one patient, probably infected sexually from a previously identified chronic carrier. In conclusion, genotype D is the main genotype and IVDU still the major risk factor for AHB in Goteborg, while transmission from immigrants appears to be of minor importance despite the fact that this group comprises over 90% of the young, highly infectious carriers.
We hypothesized that in adults with cystic fibrosis, the acquisition of a new strain of Pseudomonas aeruginosa may be associated with a pulmonary exacerbation. Eighty-four patients who were chronically infected with P. aeruginosa were prospectively followed from eight centers over a 26-month period. Patients had sputum cultures performed every 3 months while clinically stable and at the time of an exacerbation. Forty patients (48%) had an exacerbation requiring intravenous antibiotics during the study period, and in 36 of these patients, their P. aeruginosa isolates were genetically typeable by pulsed-field gel electrophoresis. In 34 of the 36 patients (94%), P. aeruginosa recovered during clinical stability and at exacerbation were of the same genotype. In only two patients (6%; 95% confidence interval, 0-18%) was a new P. aeruginosa clone cultured during an exacerbation that had not been cultured during clinical stability. There were no significant differences in antibiotic susceptibilities, measured as mean minimal inhibitory concentrations, for isolates retrieved during clinically stable periods compared with isolates retrieved during exacerbations. We conclude that for the majority of adult patients with cystic fibrosis a new pulmonary exacerbation is not caused by the acquisition of a new strain of P. aeruginosa.
Comment In: Am J Respir Crit Care Med. 2004 Apr 1;169(7):781-215044219
Atrial fibrillation (AF) renders individual patients at risk for development of an atrial thrombus. The aim of this study was to determine clinical and echocardiographic factors influencing the risk of left atrial thrombosis (LAT) in patients with persistent nonvalvular AF. Genetic variants encoding haemostatic factors have been also assessed for putative association with LAT. In the cross-sectional study, a total of 212 patients (132 males and 80 females) with nonvalvular persistent AF (duration range 48 h-90 days) have been selected. LAT was visualized by transesophageal echocardiography. The FGB G(-455)A, PAI-1 4G/5G, F5 C(-224)T, and F5 R506Q genetic markers were tested using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) approach. To reveal independent factors contributing to the thromboembolic risk in AF, a multivariate logistic model was applied. LA thrombi were found in 44 out of 212 subjects (21%). LAT was more frequently observed in patients at age >75 years (P 75 years, LVEF
We have examined restriction fragment length polymorphisms of the H-ras-1 gene in germ-line DNA from 214 lung cancer patients and 309 unaffected controls. When DNA samples were digested with MspI/HpaII, Southern blot analysis revealed at least 22 different alleles, grouped according to their frequencies as common, intermediate, and rare. The frequency of rare alleles in lung cancer patients (16/428) is significantly different (p = 0.002) from that in the control group (5/618). Individuals with rare alleles were found to be at 4.7-fold greater risk of lung cancer than those with no rare alleles.
We studied the relationship of D2 and D1 receptor gene polymorphisms and alcoholism in male Finnish alcoholics and assessed male controls. Seventy alcoholics entering a detoxification programme and 50 control individuals were recruited. Forty-three per cent of the alcoholic patients, but only 22% of controls, had the D2 receptor gene TaqI A restriction fragment length polymorphism A1 allele. The frequency of the A1 allele was significantly higher in alcoholics (p = 0.039). In comparison, no association between alcoholism and the D1 receptor gene EcoRI restriction fragment length polymorphism alleles was found. A logistic regression analysis of the alcoholic population failed to support the idea that the presence of the A1 allele would be linked to estimates of alcohol dependence severity rated with the Severity of Alcohol Dependence Questionnaire or the Michigan Alcoholism Screening Test. In conclusion, allelic association between the D2 but not D1 receptor gene and alcoholism in a genetically relatively homogenous population of male Finns was found. The results are in agreement with the view that the D2 receptor locus is involved in genetic susceptibility to alcoholism but does not give support to a special association of severe alcohol dependence and the A1 allele of the D2 receptor gene.
Frequency of promoter endothelial NO-synthase gene allelic polymorphism by using polymerase chain reaction and restriction fragment length polymorphism (RFLP-PCR) was determined in 221 patients with acute coronary syndrome (ACS) and in 83 almost healthy subjects. Data obtained indicate that different promoter allelic variant frequency differs significantly in patients with ACS and in control group. Correlation of normal homozygotes (T/T), heterozygotes (T/C) and pathologic homozygotes (C/C) was 48%, 36% and 16% respectively in patients, and in control it was 48%, 46%, 6% (P