Genetic background of type I protein C deficiency in Finland

In contrast to other populations the usually rare type II form of protein C deficiency is as common in Finland as type I deficiency. We recently reported that a single mutation explained virtually all cases of type II protein C deficiency in Finland, indicating strong founder effect. We now investigated in the same population the genetic background of type I protein C deficiency. Thirty-eight apparently unrelated families were studied. They represent the vast majority of all families with type I deficiency in Finland. A genetic defect was identified in 23 (61%) families who carried 13 different mutations. Only three of the 13 mutations have been reported in other populations. Unlike in type II deficiency, considerable heterogeneity in mutations was found in type I deficiency. Our results indicate interesting differences in mutational histories of these two different forms of protein C deficiency in Finland.

Common variants of the beta and gamma subunits of the epithelial sodium channel and their relation to plasma renin and aldosterone levels in essential hypertension

Background

Rare mutations of the epithelial sodium channel (ENaC) result in the monogenic hypertension form of Liddle's syndrome. We decided to screen for common variants in the ENaC βand γ subunits in patients with essential hypertension and to relate their occurrence to the activity of circulating renin-angiotensin-aldosterone system.

Methods

Initially, DNA samples from 27 patients with low renin/low aldosterone hypertension were examined. The DNA variants were subsequently screened for in 347 patients with treatment-resistant hypertension, 175 male subjects with documented long-lasting normotension and 301 healthy Plasma renin and aldosterone levels were measured under baseline conditions and during postural and captopril challenge tests.

Results

Two commonly occurring βENaC variants (G589S and a novel intronic i12-17CT substitution) and one novel γENaC variant (V546I) were detected. One of these variants occurred in a heterozygous form in 32 patients, a prevalence (9.2%) significantly higher than that in normotensive males (2.9%, p = 0.007) and blood donors (3.0%, p = 0.001). βENaC i12-17CT was significantly more prevalent in the hypertension group than in the two control groups combined (4.6% vs. 1.1%, p = 0.001). When expressed in Xenopus oocytes, neither of the two ENaC amino acid-changing variants showed a significant difference in activity compared with ENaC wild-type. No direct evidence for a mRNA splicing defect could be obtained for the βENaC intronic variant. The ratio of daily urinary potassium excretion to upright and mean (of supine and upright values) plasma renin activity was higher in variant allele carriers than in non-carriers (p = 0.034 and p = 0.048).

Conclusions

At least 9% of Finnish patients with hypertension admitted to a specialized center carry genetic variants of β and γENaC, a three times higher prevalence than in the normotensive individuals or in random healthy controls. Patients with the variant alleles showed an increased urinary potassium excretion rate in relation to their renin levels.

CARD15/NOD2 gene variants are associated with familially occurring and complicated forms of Crohn's disease

BACKGROUND

Variants of the caspase activating recruitment domain 15/nucleotide oligomerisation domain 2 (CARD15/NOD2) gene have been associated with susceptibility to Crohn's disease (CD).

AIM

Our aim was to evaluate the allele frequencies of the CARD15 variants R702W, G908R, and 1007fs in Finnish inflammatory bowel disease (IBD) patients and to search for possible associations between CARD15 variants and occurrence of familial forms of IBD or complicated forms of CD.

PATIENTS AND METHODS

We investigated 198 sporadic CD patients, 46 probands with familial CD, 27 CD probands from mixed IBD families, 99 unrelated patients with ulcerative colitis (UC), and 300 control individuals for the occurrence of the CARD15 gene variants R702W, G908R, and 1007fs.

RESULTS

In CD patients, the allele frequencies for the rare variants of these polymorphisms were 3.3%, 0.6%, and 4.8% (total 8.7%), and the corresponding frequencies in healthy controls were 1.8%, 0%, and 1.7% (total 3.5%) (8.7% v 3.5%; p<0.01). In UC patients allele frequencies were comparable with those in controls. The frequency of the 1007fs polymorphism variant allele was significantly higher among all CD patients than in controls (4.8% v 1.7%; p<0.01) but there was no significant difference in allele frequencies between the CD and UC groups. The 1007fs allele frequency was higher in familial CD than in non-familial cases with CD (10.9% v 3.5%; p<0.01). There were no significant differences in the allele frequencies of the R702W and G908R polymorphisms between CD patients, UC patients, and controls. We found that 15.5% of CD patients, 9.1% of UC patients, and 6.7% of controls carried at least one of the CARD15 variants. In CD patients carrying at least one of the three NOD2 variants, the ileum was affected more often than in non-carrier CD patients (90% v 73%; p<0.05), they had stricturing or penetrating disease more often than non-carriers (88% v 56%; p<0.01), and they had an increased need for bowel surgery.

CONCLUSIONS

The frequency of NOD2 gene variants was lower in genetically homogenous Finns than in other populations. The 1007fs variant was associated with CD. The occurrence of CARD15 variants predicted ileal location as well as stricturing and penetrating forms of CD.

Melanocortin-3-receptor gene variants in morbid obesity

BACKGROUND

Linkage and knock-out mice studies suggest that the melanocortin-3-receptor (MC3R) is a candidate gene for obesity.

OBJECTIVE

To evaluate whether MC3R mutations underlie morbid obesity.

SUBJECTS AND METHODS

MC3R coding and 5(')-flanking regions were sequenced in 48 subjects and the detected variants genotyped in 252 morbidly obese (BMI>/=40 kg/m(2)) Finns. Gel shifts were used to examine whether a mutation in the putative promoter alters GATA-factor binding.

RESULTS

Three common MC3R variants were found: a 17C>A variant, changing Thr6-->Lys in 16%, a 241G>A variant changing Val81-->Ile in 15%, and a -239A>G substitution in the GATA binding site in 21% of the subjects. Four other variants were detected in the 5(') flanking region. Frequencies of the three common variants did not differ between obese and contol subjects. Among the obese, the 17C>A and 241G>A variants were coinherited and associated with increased insulin-glucose ratios (P<0.05) and leptin levels (P<0.05). GATA-4 bound efficiently to wild type oligonucleotide, but only weakly to the oligonucleotide with the -239A>G mutation.

CONCLUSIONS

MC3R gene variants are common and do not explain human morbid obesity. These variants associated with subtle changes in onset of weight gain, hyperleptinemia and insulin-glucose ratios. The -239A>G mutation abolishes binding of GATA-4 to the MC3R promoter region.

Utility of the Arg/Gln polymorphism of the factor VII (FVII) gene, serum lipid levels and body mass index in the prediction of the FVII:C and FVII:Ag in North Karelia; a cross-sectional and prospective study

The arginine/glutamine (Arg/Gln) polymorphism of the factor VII (FVII) gene is associated with variation in coagulation activity (FVII:C) and antigen concentration (FVII:Ag) of the FVII protein. We estimated frequency distributions of the Arg and Gln alleles and respective genotypes in North Karelia, and evaluated the utility of this polymorphism, serum lipids, and body mass index (BMI) in the prediction of the distributions of FVII:C and FVII:Ag in a cross-sectional study and in a prospective cohort study. The sample comprised 203 males and 262 females (aged 45-64 years) who were seen twice, in 1992 and 1995. The Arg/Arg genotype and the Arg allele frequencies were among the highest reported so far (86 and 93% respectively, in men; and 89 and 94% respectively, in women). Intragenotypic means of both FVII:C and FVII:Ag were significantly higher in the Arg/Arg genotype than in the Arg/Gln genotype in both genders. Also, intragenotypic variances were different in different genotypes in females. Regression relationships between the FVII:C and FVII:Ag and serum triglyceride, and total cholesterol levels and BMI were positive in both genotypes in both genders, which has not been found in other populations. In prospective analyses, average changes in the FVII:C and FVII:Ag were genotype specific in both genders, as were also regression relationships between these changes and changes in triglyceride level in females (P = 0.065 for FVII:C and P = 0.061 for FVII:Ag). A consequence of these complex genetic architectures is that predictive utility of the Arg/Gln genotypes depends on population, gender, serum lipid levels, and BMI, and changes in these factors over time.

HFE haemochromatosis gene mutations in liver transplant patients

BACKGROUND

The majority of patients with inherited haemochromatosis carry two mutant alleles of the recently discovered HFE gene. Individuals heterozygous for the HFE mutation could be predisposed to end-stage liver disease due to other causes.

METHODS

The frequencies of the HFE gene mutations C282Y and H63D were determined in DNA samples obtained from 189 liver transplant patients and 225 healthy Finnish blood donors.

RESULTS

5% of the 189 liver transplant recipients were heterozygotes and 0.5% homozygotes for the C282Y mutation, while 16% were heterozygotes and 0.5% homozygotes for the H63D mutation. These figures were not increased in comparison to controls, of whom 11% were C282Y heterozygotes, 16% H63D heterozygotes and 0.9% H63D homozygotes. Among recipients with acute non-A-E hepatitis (n = 31), the frequency of the H63D allele was higher than in controls (21% versus 9.1%, P < 0.01). Perls' stain for iron in explanted liver specimens was positive in 28% of recipients with alcoholic cirrhosis, 26% of patients with acute non-A-E hepatitis and 14% in the rest of the recipients. The HFE genotypes did not correlate with the iron status.

CONCLUSION

Individuals heterozygous for either the C282Y or H63D mutation of the HFE gene are not at increased risk of developing chronic end-stage liver disease. However, subjects heterozygous for the H63D mutation may have an increased risk to develop fulminant non-A-E hepatitis.

Weight change and blood coagulability and fibrinolysis in healthy obese women

OBJECTIVES

To study the effect of weight loss and subsequent weight maintenance or weight regain on the activities of FVII and plasminogen activator inhibitor 1 (PAI-1) and the concentration of fibrinogen over 12 months in obese women consuming a hypoenergetic, low-fat diet with or without orlistat. In addition, the relation between the changes of the activities of PAI-1 and FVII with the changes of other cardiovascular risk factors were examined.

METHODS AND PROCEDURES

Design-a 12-month randomized double-blind weight reduction trial of placebo and orlistat. Subjects-51 healthy obese women (age 44+/-0.7 y, BMI 36.2+/-0.5 kg/m(2), mean+/-s.e.m.) Treatment-the participants were on a hypoenergetic diet (-600 kcal daily). The diet was adjusted for actual body weight (-300 kcal) at 6 months. Women were randomized to receive either orlistat 120 mg three times daily (n=25) or placebo three times daily (n=26) for 12 months according to a double-blind protocol after a 1 month run-in period. Measurements-changes of body weight, body composition, haemostatic and other cardiovascular risk factors were measured at 3-6 month intervals. The activity of plasma PAI-1 was measured by a chromogenic method, fibrinogen by the PT-derived method and the activity of FVII by the one-stage method.

RESULTS

The changes in body weight between orlistat and placebo groups were not statistically significantly different. Orlistat did not influence haemostatic factors beyond its effect on weight loss. Therefore, the results of the orlistat and placebo groups were pooled. The average weight loss at 3, 6 and 12 months was 7.6, 9.5 and 10.0 kg, respectively (P<0.001). Between 6 and 12 months, 35% of women regained weight, 24% had stable weight and 41% continued to lose weight. No changes in the mean plasma fibrinogen concentration were observed at any time point during the trial. During the first 3 months the activities of PAI-1 and FVII decreased. The decline depended on the magnitude of weight loss. Between months 6 and 12 the changes of PAI-1 and FVII activities paralleled the changes of body weight. The activities rose with weight rebound but remained below the 6-month values if weight loss was sustained or continued. The changes of serum insulin were significantly correlated with the changes of both PAI-1 and FVII at 6 months and with PAI-1 at 12 months.

CONCLUSIONS

The maintenance of modest weight loss is associated with long-term benefits in PAI-1 and FVII in obese women. The change of serum insulin is associated with the changes of PAI-1 activities. Fibrinogen is not affected by modest weight loss.

Initial P-glycoprotein expression in childhood acute lymphoblastic leukemia: no evidence of prognostic impact in follow-up

Treatment results in childhood acute lymphoblastic leukemia (ALL) have improved remarkably during the past 20 years, but still 25% of children cannot be permanently cured. Drug resistance is a major cause of poor outcome. One of the most investigated resistance mechanisms is the P-glycoprotein (P-gp)-mediated multiple-drug resistance (MDR). The authors prospectively analyzed P-gp using flow cytometry with monoclonal antibody JSB1 in a population-based series of 103 children with ALL treated according to intensive Nordic ALL protocols. Increased P-gp expression was detected in 55 patients (53%). With a cutoff value of 1% P-gp-positive blasts in bone marrow, no difference was found in event-free survival (EFS) or overall survival between children with low vs. increased P-gp expression. The 4-year EFS in the whole series was 77%. Patients with T-ALL had higher P-gp levels than the others, 3.6% vs. 1.0% (p = .002). P-gp expression did not correlate with the white blood cell count, age, sex, or cytogenetics. The authors conclude that the level of P-gp expression cannot be used as a tool for treatment stratification in childhood ALL.

Viral markers and use of factor products among Finnish patients with bleeding disorders

In the seventh national voluntary cross-sectional survey (in 1999) of Finnish patients with haemophilia A or B, type 3 von Willebrand disease or factor XIII deficiency, a plasma sample was received from 193 patients (67%). The samples were tested for hepatitis B and C, human immunodeficiency virus (HIV) and human T-cell leukaemia virus (HTLV) antibodies. Fifty-one percent of the patients were hepatitis C antibody positive and 34% hepatitis B core antibody positive. None of the patients had antibodies against HIV or HTLV. Eighteen percent of the patients had an elevated alanine aminotransferase activity. Abnormal alanine aminotransferase was significantly associated with hepatitis C seropositivity. No new seroconversions were detected among the haemophiliacs or patients with type 3 von Willebrand disease when compared with the last two surveys in 1993 and 1996, and there was no seroconversion in sole users of solvent/detergent-treated factor products. Currently, 32% of the patients use prophylactic factor treatment as their principal mode of therapy, particularly the younger patients with severe forms of the bleeding diseases.

Single founder mutation (W380G) in type II protein C deficiency in Finland

The present study investigated the genetic basis for type II protein C deficiency in Finland, where this form has an unusually high incidence. We demonstrated that, first, a single novel mutation W380G in the protein C gene (PROC) explained 25/26 index patients, estimated to represent two thirds of all families with type II deficiency in Finland. Second, extended chromosomal conservation, i.e. a specific haplotype, around the W380G mutation was indicated in unrelated patients. Third, a local geographical origin for the W380G mutation was suggested by genealogical data. These results are in contrast to the heterogeneity in type II protein C deficiency elsewhere, but closely parallel disorders of the Finnish disease heritage. The high frequency of the type II disease can be explained by founder effect and subsequent enrichment of a single mutation in Finland. The present study also provided a simple means for genetic diagnosis of this disease and the genetic test can be included in the routine screenings in this population.

Higher concentrations of serum transferrin receptor in children than in adults

BACKGROUND

The serum transferrin receptor (TfR) concentration in adults is suggested to provide a sensitive measure of iron depletion and together with the serum ferritin concentration to indicate the entire range of iron status, from iron deficiency to iron overload. However, little is known about TfR concentrations in children.

OBJECTIVE

Our objective was to compare serum TfR and ferritin concentrations and their ratios in children and adults and look for correlations between TfR concentrations and other measures of iron status.

DESIGN

Our study groups were healthy 1-y-old infants (n = 36), 11-12-y-old prepubertal boys (n = 35), and 20-39-y-old men (n = 40).

RESULTS

TfR concentrations were higher in infants (x; 95% reference interval: 7.8 mg/L; 4.5, 11.1) than in prepubertal boys (7.0 mg/L; 4.7, 9.2) and higher in prepubertal boys than in men (5.8 mg/L; 3.1, 8.5). Geometric mean TfR-ferritin ratios were higher in infants (316; 95% reference interval: 94, 1059) than in prepubertal boys (219; 78, 614) and higher in prepubertal boys than in men (72; 23, 223). By multiple linear regression analysis, the best predictors of TfR concentration were serum iron (P = 0.004) and log serum ferritin (P < 0.0001), both being inverse correlations (R2 = 0.32). Mean corpuscular volume, blood hemoglobin, transferrin iron saturation, transferrin, and even age seemed to not have an influence on the TfR concentration and erythropoiesis was not a determinant of TfR concentration.

CONCLUSIONS

Low serum ferritin and iron concentrations, even within the normal physiologic range, result in high TfR concentrations. The lower the iron stores, the stronger the influence of ferritin on TfR. A high TfR concentration in children, especially in infants, is a response to physiologically low iron stores. Age-specific reference concentrations for TfR are needed.