Missense MED12 variants in 22 males with intellectual disability: From nonspecific symptoms to complete syndromes

We describe the phenotype of 22 male patients (20 probands) carrying a hemizygous missense variant in MED12. The phenotypic spectrum is very broad ranging from nonspecific intellectual disability (ID) to the three well-known syndromes: Opitz-Kaveggia syndrome, Lujan-Fryns syndrome, or Ohdo syndrome. The identified variants were randomly distributed throughout the gene (p = 0.993, χ² test), but mostly outside the functional domains (p = 0.004; χ² test). Statistical analyses did not show a correlation between the MED12-related phenotypes and the locations of the variants (p = 0.295; Pearson correlation), nor the protein domain involved (p = 0.422; Pearson correlation). In conclusion, establishing a genotype-phenotype correlation in MED12-related diseases remains challenging. Therefore, we think that patients with a causative MED12 variant are currently underdiagnosed due to the broad patients' clinical presentations.

The EntOptLayout Cytoscape plug-in for the efficient visualization of major protein complexes in protein-protein interaction and signalling networks

Motivation

Network visualizations of complex biological datasets usually result in ‘hairball’ images, which do not discriminate network modules.

Results

We present the EntOptLayout Cytoscape plug-in based on a recently developed network representation theory. The plug-in provides an efficient visualization of network modules, which represent major protein complexes in protein–protein interaction and signalling networks. Importantly, the tool gives a quality score of the network visualization by calculating the information loss between the input data and the visual representation showing a 3- to 25-fold improvement over conventional methods.

Availability and implementation

The plug-in (running on Windows, Linux, or Mac OS) and its tutorial (both in written and video forms) can be downloaded freely under the terms of the MIT license from: http://apps.cytoscape.org/apps/entoptlayout.

Supplementary information

Supplementary data are available at Bioinformatics online.

Hypertriglyceridemia, the coronary heart disease risk marker âεœsolvedâε□

Both epidemiological and intervention studies have shown that hypertriglyceridemia is a significant cardiovascular risk factor. The large variation of the triglyceride values is explained by the influence of several modifying factors, which are difficult to standardise. Therefore hypertriglyceridemia should be considered rather as risk marker, than risk factor. The measurement of the apolipoprotein CIII level, which is a more stable parameter of the triglyceride rich lipid particles, is now becoming more widespread. This parameter is also able to substitute the assessment of the small dense LDL form that has a controversial significance. The clinical benefit of reduction of triglyceride concentration and the accompanying increase of HDL cholesterol level by fibrates, in the prevention of the coronary heart disease (CHD) events, have been demonstrated in several prospective, placebo-controlled trials. The VA-HIT study, enrolling the largest number of patients, has shown that fibrates have another effect, presumably influencing the insulin resistance independently of lipid levels that is also able to reduce the CHD events.

Increased frequency of the C3*F allele and the Leiden mutation of coagulation factor V in patients with severe coronary heart disease who survived myocardial infarction

The aim of the present study was to compare the frequencies of the F allele of C3 complement component and the Leiden mutation of coagulation factor V in patients with severe coronary heart disease (CHD) who survived myocardial infarction (MI; group A), and those who had no MI in their case history (group B). We have determined the C3 allele frequencies by electrophoresis, and Leiden mutation by PCR in 338 patients with severe CHD and in 490 and 523 healthy controls, respectively. The C3*F allele frequency was significantly (p = 0.006) higher in group A (0.213) that in group B (0.132). A significant (p = 0.045) difference was found between < or = 60-year group A (0.077) and group B (0.029) patients in the frequency of Leiden mutation. These findings indicate that the C3*F allele and the Leiden mutation may be associated with an increased risk of developing myocardial infarction in CHD patients.

Involvement of polymorphisms in the chemokine system in the susceptibility for coronary artery disease (CAD). Coincidence of elevated Lp(a) and MCP-1 -2518 G/G genotype in CAD patients

The central role of chemokines in the pathogenesis of atherosclerosis has been made clear. Recently polymorphisms in the gene regulatory region of MCP-1 and in the promoter region of RANTES have been found, which increase the expression of these chemokines. We investigated the role of these polymorphisms together with the chemokine SDF-1-801A and the chemokine receptors CCR2-64I and CCR5Delta32 mutations in 318 patients with coronary artery disease (CAD) referred to coronary bypass surgery, comparing them with 320 healthy controls. The prevalence of the MCP-1 -2518 G/G homozygotes was significantly higher among CAD patients than among controls (P<0.005; OR=2.2 (95% CI 1.25-3.92). The Lp(a) levels of CAD patients with G/G genotype were significantly higher than those in patients with G/A or A/A genotypes. No CAD patients homozygous for the CCR5Delta32 and CCR2-64I mutations have been found. The genotype distributions of the two alleles deviated from the Hardy Weinberg equilibrium in patients, indicating that the numbers of homozygotes were significantly lower than expected. The MCP-1 -2518G variant in homozygous form appears as a genetic risk factor for severe CAD. This genotype is associated with elevated Lp(a) levels in patients. Individuals homozygous for CCR2-64I or CCR5Delta32 mutations are at reduced risk for severe CAD.

The association of serum lipoprotein(a) levels, apolipoprotein(a) size and (TTTTA)(n) polymorphism with coronary heart disease

BACKGROUND

The association between lipoprotein(a) levels, apolipoprotein(a) size and the (TTTTA)(n) polymorphism which is located in the 5' non-coding region of the apo(a) gene was studied in 263 patients with severe coronary heart disease and 97 healthy subjects.

METHODS

Lp(a) levels were measured by ELISA, apo(a) isoform size was determined by SDS-agarose gel electrophoresis, and analysis of the (TTTTA)(n) was carried out by PCR. For statistical calculation, both groups were divided into low (at least one apo(a) isoform with < or = 22 Kringle IV) and high (both isoforms with >22 KIV) apo(a) isoform sizes, and into low number (<10 in both alleles) and high number of (> or =10 at least one allele) TTTTA repeats.

RESULTS

Lp(a) levels were higher (P=0.007), apo(a) isoforms size < or =22 KIV and TTTTA repeats > or = 10 were more frequent (P=0.007 and 0.01) in cases than in controls. Lp(a) levels were found to be increased with low apo(a) weight in both groups (both P<0.0001). In multivariate logistic regression analysis, only the Lp(a) levels (P=0.005) and (TTTTA)(n) polymorphism (P=0.002) were found to be significantly associated with CHD.

CONCLUSION

Nevertheless, these results indicate that in CHD patients the (TTTTA)(n) polymorphism has an effect on Lp(a) levels which is independent of the apo(a) size.

Anti-cholesterol antibodies (ACHA) in patients with different atherosclerotic vascular diseases and healthy individuals. Characterization of human ACHA

In animal experiments the protective role of anti-cholesterol antibodies (ACHA) in the development of atherosclerosis has been demonstrated. Despite the fact that ACHA are present in the serum of healthy humans, no data on the occurrence of these antibodies in human diseases are available. We determined serum concentrations of IgG type ACHA by an enzyme immunosorbent assay in 600 patients with atherosclerotic vascular diseases (86 patients with peripheral occlusive atherosclerosis, 146 patients with cerebrovascular diseases, 341 patients with severe coronary heart disease (CHD) who received aorto-coronary by-pass, 27 patients with myocardial infarction who did not undergo by-pass operation), in 57 patient controls (complaints of CHD, without coronarographic alterations) and in 218 healthy individuals. ACHA were present in the sera of all persons tested. No serum cofactor is needed for the binding of human ACHA to solid phase cholesterol, binding can be inhibited dose-dependently by LDL and even more strongly with LDL/VLDL preparations purified from human serum. ACHA levels were found to be considerably lower in patients with peripheral occlusive atherosclerosis and cerebrovascular diseases compared with the levels in healthy individuals. By contrast, the ACHA levels of patients with CHD were considerably higher. No differences in the IgG subclass distribution and binding efficiency of ACHA in the sera of CHD patients and controls were found. Thus, our present findings indicate that both low and high ACHA production may be associated with different atherosclerotic vascular diseases.

[Effect of ciprofibrate on the endothelial dysfunction of patients with combined dyslipidemia]

Endothelial dysfunction can be detected in the early phase of atherosclerosis. Two unresolved questions have been raised the wether, (1) the dyslipidemic state alone without any other risk factors can be harmful for the endothelial function measured by ultrasound, and (2) the use of the antilipidemic fibrate is sufficient to influence the endothelial functions. From 38 subjects with solitary combined dyslipidaemia 32 (84%) showed endothelial dysfunction measured by flow mediated vasodilatation (FMD) on the forearm and this group of patients was featured only by higher fibrinogen levels (no differences on BMI, serum lipid and glucose level). The patients with endothelial dysfunction were treated with 100 mg of ciprofibrate per day (12 women, 20 men, average age: 44.6 +/- 9 years, BMI 24.6 +/- 3.4 kg/m2). The pretreatment serum lipid levels were: total cholesterol 6.9 +/- 0.4, triglyceride 4.2 +/- 0.3, HDL cholesterol 1.13 +/- 0.21 mmol/l. After the 4 weeks treatment period the cholesterol and triglyceride level decreased, the concentration of HDL cholesterol increased significantly, which changes were in correspondence with significant improvement of FMD (3.9 +/- 0.7% vs. 7.0 +/- 1.6%). The level of fibrinogen also declined significantly. At the 8th week there were no significant further changes compared to the data received at the 4th week. Using the lineal regressive analysis the improved vasodilatator respond at both check points was correlated only with the fall of total cholesterol level. The ciprofibrate was suspended after the 8th week for a 4 weeks period and the triglyceride and the fibrinogen levels increased whereas the HDL cholesterol level decreased significantly. The FMD impaired significantly (to 5.8 +/- 1.2%). There were no correlations among the changes. The results demonstrated the lipid and probably non-lipid-factors are important in these early damages of endothelial functions.

Comparative study on antibodies to human and bacterial 60 kDa heat shock proteins in a large cohort of patients with coronary heart disease and healthy subjects

BACKGROUND

Recent observations indicate an association between antibodies against mycobacterial heat shock protein (hsp65) and coronary heart disease (CHD). Previously, we reported on marked differences in antigen specificity and complement activating ability of anti-hsp65 antibodies and auto-antibodies against human heat shock protein, hsp60. Here, we investigated whether there are differences between antih-sp65 and anti-hsp60 antibodies in their association with CHD.

DESIGN

We measured by ELISA the levels of antibodies to hsp65, hsp60 and E. coli-derived GroEL in three groups: Group I, 357 patients with severe CHD who underwent by-pass surgery; Group II, 67 patients with negative coronary angiography; Group III, 321 healthy blood donors. Antibodies against Helicobacter pylori were also measured by commercial ELISA.

RESULTS

As calculated by multiple regression analysis, the levels of anti-hsp60 auto-antibodies were significantly higher in Group I compared to Group II (P = 0.007) or Group III (P < 0.0001). By contrast, although concentrations of anti-hsp65 and anti-GroEL antibodies in Group I were higher than in Group III, no significant differences between Group I and Group II were found. Antibodies to the two bacterial hsp strongly correlated to each other, but either did not correlate or weakly correlated to hsp60. In Group I, serum concentrations of anti-H.pylori antibodies significantly correlated with those of anti-hsp65 and anti-GroEL antibodies but they did not correlate with the anti-hsp60 antibodies.

CONCLUSIONS

As to their clinical relevance, a remarkable difference become evident between antibodies to human hsp60 and antibodies against bacterial hsp in the extent of association with CHD. On the basis of these findings and some pertinent literature data, an alternative explanation for the association between high level of anti-hsp antibodies and atherosclerotic vascular diseases is raised.

Receptor polymorphisms and diseases

The aim of our review is to summarize common genetic variations of some receptors associated with clinical consequences, which were not outlined in the previous special issue of this journal. Because of the multiple pathomechanisms of diseases, a set of genetic variation can play a role in the development of pathological conditions. From the data available three articles would merit a greater interest. In systemic lupus erythematosus the associations related to some polymorphisms of Fc-, tumor necrosis factor (TNF) alpha- and interferon receptor may explore new autoimmunological and inflammatorical pathomechanisms. In the endocrinology, the androgen receptor repeat polymorphism will exert significant aspects in the development of prostate cancer. The pleoitropic responsibility of vitamin D3 receptor polymorphism in the pathogenesis of immunological disorders (primary biliary cirrhosis, inflammatory bowel disease, type 1 diabetes mellitus) and of malignancies (malignant melanoma, breast cancer) shed light on the importance of common nuclear receptors. Nevertheless, in the future studies a more consistent approach minimizing requirement bias in the selection of patients will approve our understanding the role of genetic influence on the pathogenesis of diseases.

Frequency of the R3500Q mutation of the apolipoprotein B-100 gene in a sample screened clinically for familial hypercholesterolemia in Hungary

Familial hypercholesterolemia (FH) and familial defective apolipoprotein B-100 (FDB) cause early onset of coronary heart diseases (CHD). According to the recommendations of the international MEDPED program, we tried to find FH cases. We analyzed 73 FH probands and their 304 first-degree relatives. A total of 39 probands were found from the 21000 subjects screened (1:538) from family doctors' registers recording all citizens, while the remaining 34 were derived from screened patients from lipid clinics. In our FH probands, four cases of FDB (R3500Q mutation) were diagnosed with allele-specific PCR, and the mutation was also detectable in five cases out of seven living family members. In the remaining 69 FH families, 156 people were diagnosed clinically with FH, and 31.8% of the males (against 13% of the not clinically diagnosed FH males, P<0.01), and 32.4% of the females (against 13.5% of the not clinically diagnosed FH females, P<0.01) suffered from early onset CHD. The plasma total cholesterol level of the FDB patients, especially in the younger patients, was very close to normal values. Therefore, the FDB patients seem to be under-represented in this type of survey. Because FDB is one of the independent causes of early onset CHD, the R3500Q mutation should be considered in families with a high frequency of cardiovascular diseases.

Frequencies of certain complement protein alleles and serum levels of anti-heat-shock protein antibodies in cerebrovascular diseases

BACKGROUND AND PURPOSE

A strong correlation exists between the intensity of atherosclerotic alterations in different arteries. Marked differences exist, however, in the age and sex distribution and risk factors for coronary heart disease (CHD) and cerebrovascular disease (CVD). We therefore performed genetic and immunologic studies in patients with CVD.

METHODS

We studied 292 patients with CVD (stroke or transient ischemic attack) and as control either 198 healthy blood donors and 485 healthy elderly (aged >60 years) people (genetic study) or 94 blood donors aged 45 to 60 years and 49 healthy elderly (aged >60 years) people (anti-heat-shock protein [hsp] measurements). Allele frequencies of 3 genes (C4A, C4B, and C3) encoding proteins of the complement system were determined by electrophoresis and immunofixation. Serum concentration of autoantibodies against 60-kDa heat-shock protein (anti-hsp60) was measured by the enzyme-linked immunosorbent assay method.

RESULTS

Marked differences were observed between CVD patients and controls in the genetic studies. In the CVD patients aged >60 years, the frequency (11.3%) of the deficient allele of the C4B gene (C4B*Q0) was significantly (P:=0.0003) higher than that of the healthy controls (5.4%). By contrast, in the group aged 45 to 60 years, the frequency of the C4B*Q0 allele was lower in patients than in controls. Serum concentration of anti-hsp60 in the CVD patients did not differ from control values.

CONCLUSIONS

In previous studies C4B*Q0 frequency was reported to be higher in CHD patients aged 45 to 60 years than in aged-matched controls. Moreover, high anti-hsp60 levels were found in CHD patients. These findings contrast with our present report of lower frequency of C4B*Q0 in CVD patients. Therefore, genetic and immunologic factors may at least partly explain the differences between the natural history and risk factors of CHD and CVD.

Secondary cutaneous infiltration in B cell chronic lymphocytic leukemia

We describe a patient presenting with B cell chronic lymphocytic leukemia (B-CLL) who subsequently developed cutaneous infiltrates. Specimens of the blood, bone marrow and cutaneous infiltrations all showed the same heavy-chain gene rearrangement. Following failure of conventional chemotherapy, and in view of the similarity of the disease to cutaneous T cell lymphoma, interferon-alpha therapy was employed with satisfactory results. Introduction of this cytokine to the therapeutic modalities for secondary cutaneous B-CLL would hopefully change the poor outcome of this entity, or at least could produce a better quality of life. Loss of histidine decarboxylase activity in the infiltrating cells - in contrast to circulating lymphocytes - may be associated with the transformation of B-CLL to a more aggressive infiltrative form, offering a possible explanation for tissue invasiveness. The changing character of the disease raises the possibility of a second mutational event in the course of B-CLL.

[Secondary cutaneous infiltration in B-cell chronic lymphocytic leukemia (B-CLL)]

Authors report here on a case presenting as B-CLL and complicated with cutaneous infiltration involving the legs and the trunk a year later. Immunohistochemic analysis and the immunoglobulin heavy chain gene rearrangement confirmed cell invasion into the skin identical with the underlying disorder. After failure of conventional chemotherapy, interferon alpha 2b therapy has been started with satisfactory result. Few cases presenting cutaneous infiltration in the course of B-CLL has already been reported in the literature. Secondary cutaneous B-cell lymphoma represents an entity of the poorest prognosis in comparison with primary cutaneous form treated with conventional therapy as well as with lymphomas lacking skin manifestations. Interferon alpha 2b therapy cleans up the skin and yields a favourable survival so it's introduction recommended in this entity. Authors summarise the characteristics of secondary cutaneous B-cell lymphomas on the basis of literature survey. According to authors investigations histidine decarboxylase activity was found to be absent from the lymphocytes infiltrating the skin in contrast to those remaining in the circulation. This seems to be a newly recognised feature of these cells. The changing character of the disease raises the possibility of an altered gene expression pattern of the cells invading the skin. Authors summarise data from the literature concerning suspected molecular mechanism of tissue invasion.

Influence of apolipoprotein E genotypes on serum lipid parameters in a biracial sample of children

The goals of this study were to compare the allelic distribution of the apolipoprotein E(apoE) gene in Hungarian and Hungarian Gypsy children and to examine the impact of apoE polymorphism on quantitative levels of lipids in the two racial groups. Our data yielded calculated allele frequencies of 6.4% and 8.9% for apoE2; 83.8% and 73.8% for apoE3; and 9.8% and 17.3% for apoE4 in Hungarian and in Gypsy children, respectively. The frequency of the apoE4 allele was significantly higher (P<0.05) in Gypsy children than in Hungarians. The effect of apoE genotypes on serum lipid parameters differed considerably in the two racial groups. In the Gypsy group the lowest total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C) and triglyceride levels were in the E3/E3 group and these values differed significantly (P<0.0001 for TC and LDL-C and P<0.01 for triglyceride) from the values in the E2/E3 and E3/E4 groups. There were no significant differences in TC, LDL-C and triglyceride levels between E2/E3 and E3/E4 groups. The high-density lipoprotein-cholesterol (HDL-C) levels did not differ significantly among the genotype groups. In Hungarian children, the apoE2/3 group displayed lower, the E3/4 group higher, values of TC and LDL-C than in the E3/3 group, but the differences were not significant (P>0.05). HDL-C and triglyceride values did not differ among the genotype groups.

CONCLUSION

Our results demonstrate that the apolipoprotein E allele frequencies differ between Hungarian and Gypsy children and suggest that these alleles influence the serum lipid levels, but other genetic and environmental factors can considerably change this effect.

Angiotensin II type 1 receptor gene polymorphism and mitral valve prolapse syndrome

BACKGROUND

Mitral valve prolapse syndrome (MVPS), a term applied to patients who have a variety of symptoms, has been associated with autonomic or neuroendocrine dysfunction. Recent evidence suggests that effects of angiotensin II mediated by the angiotensin II type 1 (AT(1)) receptor are involved in modulation of cardiovascular autonomic control in human beings. Association of a genetic polymorphism (A-C(1166)) of the AT(1) gene with abnormal vasomotion and low blood pressure related to autonomic control has been reported recently. Because the role of this genetic variant in MVPS has not been studied, we performed a case-control study of the A-C(1166) variant in a group of 76 white subjects with MVPS.

METHODS AND RESULTS

All patients were genotyped by use of a mismatch polymerase chain reaction/Afl II restriction fragment length polymorphism analysis. Frequency of the C(1166) allele was 0.4 in patients with MVPS and 0.26 in control patients. The difference in genotype (chi square = 6.5; P <.05) and allele (chi square = 5.9; P =.02) frequencies between the groups was significant. The odds ratio in favor of carrying the C allele was 4 times greater for patients with MVP than for control patients (95% confidence interval 1.4 to 12.1).

CONCLUSIONS

The current results indicate that the A-C(1166) polymorphism of the angiotensin II type 1 receptor gene is associated with MVPS in the white population.

Antibodies against human heat-shock protein (hsp) 60 and mycobacterial hsp65 differ in their antigen specificity and complement-activating ability

Although complement activation appears to have an important role both in the early and late phases of atherosclerosis, the exact mechanism of the initiation of this activation is still unknown. Since injuries of the endothelial cells are known to result in increased stress-protein expression we tested the complement-activating ability of recombinant human 60 kDa heat-shock protein (hsp60). Human hsp60 was found to activate the complement system in normal human serum in a dose-dependent manner. Activation took place through the classical pathway. The lack of complement activation in agammaglobulinemic serum indicates that the classical pathway is triggered by anti-hsp60 antibodies. Hsp60 activated complement in the sera of 74 patients with coronary heart disease as well, and a strong positive correlation (r = 0.459, P < 0.0001) was found between the extent of complement activation and the level of anti-hsp60 IgG antibodies but there was no correlation to the level of anti-hsp65 IgG antibodies. Further distinction between anti-hsp60 and anti-hsp65 antibodies was obtained from competitive ELISA experiments: binding of anti-hsp60 antibodies to hsp60-coated plates was inhibited only by recombinant hsp60 and vice versa. Our present findings indicate that anti-hsp60 and anti-hsp65 antibodies are distinct, showing only partial cross-reactivity. Since complement activation plays an important role in the development of atherosclerosis and the levels of complement-activating anti-hsp60 antibodies are elevated in atherosclerosis-related diseases, our present findings may have important pathological implications.

Chemokine receptor CCR2 and CCR5 polymorphisms in children with insulin-dependent diabetes mellitus

Studies have shown the important roles of several regulatory and proinflammatory cytokines in insulin-dependent diabetes mellitus (IDDM). CC-chemokine receptors CCR2 and CCR5 bind chemokines that are involved in the trafficking of leukocytes in both basal and inflammatory states. A common 32-bp deletion mutation in the CCR5 gene (CCR5delta32) and a G-to-A nucleotide substitution in the CCR2 at position 190 (CCR2-64I) have recently been described. In the present study, we have determined the frequency of the CCR5delta32 and CCR2-64I alleles in children with IDDM [n = 115; age 1-14 (9.3+/-4.3) y] and in nondiabetic subjects [n = 280; age 1-14 (8.5+/-4.5) y]. The CCR5delta32 allele frequencies were 0.117 in children with IDDM and 0.111 in nondiabetic subjects, indicating that the deletion allele has no association with IDDM. The CCR2-64I allele frequency in children with IDDM was 0.226, which differed significantly from the allele frequency in controls (0.114, p = 0.001). The role of this mutation in IDDM cannot be explained yet, but, because CCR2 mediates the chemotaxis of CD4+ and CD8+ T cells to areas of inflammation and because these cells play important roles in insulitis, a mutation in the CCR2 gene may contribute to the susceptibility to the disease. Alternatively, the 64I allele could be a marker of a linked mutation through linkage disequilibrium. According to these results, the CCR2 gene may be a new candidate for the susceptibility locus of IDDM. However, because no IDDM locus has been identified near 3p21 until now, further investigations are needed to confirm this statement.

Increased apolipoprotein E4 allele frequency is associated with vascular dementia in the Hungarian population

INTRODUCTION

The regulatory role of apolipoprotein E in lipid transport and metabolism was utilized to investigate the allelic association between the apolipoprotein E4 (apoE4) allele and vascular dementia (VD) in a selected sample of Hungarian patients with multiple deep subcortical infarcts and leukoaraiosis.

MATERIAL AND METHODS

Thirty-four Caucasian VD cases and 79 healthy control probands were involved in this study according to the criteria of ICD-10 and NINDS-AIREN International Workshop Diagnostic Criteria. The genomic DNA was isolated from whole blood and the apoE alleles were determined by polymerase chain reaction.

RESULTS

The E2, E3 and E4 allele frequencies in the VD group were 5%, 76%, and 19%, respectively; and significant (P<0.03) differences were found in comparison with the data on the healthy controls (E2, 6%; E3, 87%; E4, 8%). The apoE4 allele frequency was intermediate between HC and Alzheimer's dementia group (28%).

CONCLUSION

These results indicate that the apoE4 allele could be a risk factor not only for certain primary degenerative, but also for vascular dementias.

No mitochondrial haplotype was found to increase risk for Alzheimer's disease

BACKGROUND

Seventy Alzheimer's disease (AD) patients and 80 age- and sex-matched controls were analyzed for mitochondrial mutations T4336C and A3397G, reported to be associated with AD, and for mutations T4216C/G13708A characteristic for a normal human haplotype associated with increased frequency of occurrence of some hereditary diseases. The distribution of apolipoprotein E (apoE) alleles was also analyzed.

METHODS

Mitochondrial DNA was amplified by polymerase chain reaction, and the presence of mutations was detected by digestion with approximately chosen restriction endonucleases (restriction fragment length polymorphism).

RESULTS

One patient and 2 controls were found to belong to the T4336C/T1630C haplotype. No A3397G mutant was detected. The T4216C/G13708A haplotype occurred at 5/70 and 5/80 frequency in the two groups. Prevalence of the apoE4 allele was significantly higher in AD patients (25%) than in the control group (8.1%).

CONCLUSIONS

The T4336C/T16304C mutations were not found to associated with AD, and no predisposing mitochondrial haplotypes were found.

Cytokine regulation of the acute-phase protein levels in multiple myeloma

BACKGROUND

Interleukin (IL) 6 has an important role in the regulation of acute-phase proteins (APPs) during an acute-phase response. We studied IL-6 and other cytokines to determine if they regulate serum APP levels in the same way under the condition of the aberrant, long-lasting 'acute-phase response' that occurs in patients with chronic inflammation and cancer.

METHODS

Serum levels of nine positive APPs [CRP, SAA, C1-INH, Bf, C5, C8, C9, alpha 1-acidic glycoprotein (AGP) and haptoglobin] and two negative APPs [transferrin and alpha 2-HS glycoprotein (AHSG)] were measured using immunochemical methods in 59 multiple myeloma patients and in 72 healthy control subjects. Serum IL-6 and tumour necrosis factor (TNF) alpha levels were determined by bioassays.

RESULTS

IL-6 was negatively correlated with five out of nine (C1-INH, C8, C9, AGP and haptoglobin) positive APPs but positively correlated with C-reactive protein (CRP). When patients with high and low IL-6 serum concentration were compared, CRP levels were higher, AGP and haptoglobin levels were lower in the high- than in the low-L-6 group, whereas no significant difference between the two groups was found in levels of the other positive and negative APPs. TNF-alpha levels were negatively correlated with transferrin and AHSG levels. No difference in the levels of positive APPs was observed between patients with low and high TNF-alpha serum concentration. By contrast, levels of both transferrin and AHSG were significantly lower in the high- than in the low-TNF-alpha group.

CONCLUSIONS

These findings indicate that, except for regulation of the negative APPs by TNF-alpha, the mechanism of APP regulation is different under the conditions of the short-term and the chronic, long-lasting 'acute-phase reaction'.

[Incidence of familial defective apolipoprotein B-100 in cases of patients diagnosed with familial hypercholesterolemia]

Familial Hypercholesterolemia (FH) and Familial Defective Apolipoprotein B-100 (FDB) are monogenic, autosome, dominantly inherited diseases appearing as type II/a primary hypercholesterolemia. The frequency of the heterozygositic forms is 1:700-1:500 in European population. Both forms of hypercholesterolemia causes early onset coronary heart diseases (CHD). According to the recommendations of the international MED-PED program (Make Early Diagnoses--Prevent Early Death), we found 73 FH cases and their 377 first relatives (parents, siblings, children) were also assessed. 156 patients were diagnosed clinically FH (131 alive and 25 deceased), and 31.8% of the males and 32.4% of females suffered from early onset CHD. One family with FH consists of 5.46 members on the average and there are 2.39 FH patients in one family. In our FH cohort four patients with FDB (R3500Q mutation) were diagnosed with allelspecific PCR, and the mutation was detectable also in 9 cases out of 11 living family members. The plasma total cholesterol level of the FDB patients--especially at younger age--was very close to the normal values, which is in contrast to the findings in FH patients. Nevertheless, FDB can be one of the independent causes of the early onset CHD. Therefore, in families with high frequency of cardiovascular diseases the R3500Q mutation has to be considered.

Association of angiotensin II type 1 receptor polymorphism with resistant essential hypertension

Angiotensin II type 1 receptor (AT1) mediates the vasoconstrictive and growth-promoting effect of angiotensin II in humans. It has been reported that a polymorphism of the AT1 gene (an A/C transversion at position 1166: A-C1166) occurs more frequently in resistant hypertensives taking two or more antihypertensive drugs. On the contrary, a recent study of the influence of the A-C1166 polymorphism on aortic stiffness demonstrated that the distribution of the genotypes did not differ between normotensive and hypertensive subjects. In addition, a recent population-based survey of Caucasian hypertensives reported lower blood pressure values in CC homozygotes than in heterozygotes and AA homozygotes. Because of these controversial results and the lack of a sufficient amount of data the present study was designed to assess the contribution of the AT, gene A-C1166 polymorphism to resistant essential hypertension. Forty-eight subjects with resistant essential hypertension (HT) and 48 normotensive (NT), age and sex-adjusted controls (from a population of 300 healthy blood donors) were selected. All subjects were genotyped for the A-C1166 polymorphism in the 3'-UTR of the AT1 gene using PCR-based techniques. The influence of genotype on blood pressure (BP) was investigated using ANOVA Randomized Complete Block (ANOVA RCB) design according to sex, age and BMI. There were no significant differences in allele or genotype frequencies between HT and NT subjects (X2 = 0.61; P = NS). In HT subjects higher values of systolic blood pressure were associated with the C allele of the AT1 gene only in older and overweight patients (P < 0.001 and P < 0.001, respectively). Also in HT patients an association between the presence of the C allele of the AT1 gene and higher values of diastolic blood pressure was present in overweight patients (P = 0.001). These results suggest that in resistant hypertensive subjects the AT1 A-C1166 polymorphism is potentially involved in the regulation of blood pressure. As the effects of genotypes on blood pressure are pronounced in older and overweight subjects this polymorphism may amplify the effects of age and BMI on resistant essential hypertension.

[Characteristics of apolipoprotein polymorphism in a Hungarian population]

One of the main risk factors of ischaemic heart disease is the dyslipidaemia. In the development of altered lipid metabolism genetic factors play a significant role. The hereditary backgrounds have to be known in order to reveal the most important possibilities in diagnostics and prevention.

Association of the apolipoprotein A-IV codon 360 mutation in patients with Alzheimer's disease

Specific apolipoprotein E (apoE) alleles determines, in large part, the risk and mean age of onset familial and sporadic Alzheimer disease. The unresolved issues in this relationship support the contribution of other environmental and genetic parts. Among the candidates the apolipoprotein A-IV (apoA-IV) a component of plasma lipid particles similar to apoE has been suggested to play a role in brain metabolism. Since apoA-IV has a common DNA based protein polymorphism with a different function we determined apoA-IV (360:Gln:His) DNA polymorphism in 63 late-onset sporadic Alzheimer's patients. We found that the APOA-IV (360:His) heterozygosity occurs significantly more frequent (20.6% vs. 7.0%, P = 0.021, odds ratio 3.4 (confidence interval 1.1-10.2)) comparing age-matched controls with normal mental score. The significant difference in apoA-IV allelic distribution has been detected dominantly in patients with non-apoE4 genotype. Our data indicate that the apoA-IV-2 allele may confer one of the susceptibility markers for Alzheimer's disease (AD) and strengthen the polygenic risk determination of the variability in expression of AD.

[Study of low density lipoprotein (LDL) receptor mutations, using restriction endonucleases, in familial hypercholesterolemia]

Familial hypercholesterolemia (FH) is an autosomal dominant metabolic disorder caused by different mutations in the low density lipoprotein receptor (LDLR) gene. We analyzed 13 families (23 patients) with FH and 36 subjects with normocholesterolemia by restriction fragment polymorphism (RFLP) using enzymes Xbal, BgIII and PvuII. At the 3' end of LDLR an extra 4.4 kb band has been found by Xbal digestion in one patient and it has been proved to be a "de novo" form of mutation. In the 5' end of LDLR gene a combined mutation has been identified in two FH families. The Xbal RFLP has yielded an extra band of 24.5 kb and an another extra band of 17.5 kb has been found by BgIII digestion. It has been suggested that the simultaneous occurrence of 3.3 kb extended deletion (intron 3) and 4.8 kb extended insertion (intron 1) is present. In our study the frequency of P2 allele (PvuII RFLP) in FH patients did not differ from normocholesterolemic controls.

Apolipoprotein E allele frequencies in patients with late-onset sporadic Alzheimer's dementia in Hungary

INTRODUCTION

The presence of the apolipoprotein E4 allele (apoE4) has been recognized as a risk factor for the development of presenile and senile forms of Alzheimer's dementia (AD).

MATERIAL AND METHODS

The apoE alleles frequency of 71 normal controls (NC), 60 demented controls (DC) and 50 senile type AD subjects was determined by polymerase chain reaction in order to get data about the apoE polymorphism of the Hungarian AD population.

RESULTS

The apoE3/3 genotype was the most common in all groups. The apoE4 frequency was significantly higher (28%) in the AD group than that was (7% and 9%) in the NC and DC populations, respectively. No apoE4 homozygotes were found in the DC group and the number of heterozygotes was lower in the DC than in the AD group.

CONCLUSION

The results are in good agreement with others in the literature and support the occurrence of an increased apoE4 allele frequency in Hungarian senile AD population.

Lipoprotein(a) concentration and phenotypes in primary biliary cirrhosis

We studied a selected group of 39 female patients suffering from primary biliary cirrhosis (PBC). This disease is characterized by typical lipoprotein alterations and elevated concentrations of serum cholesterol. Despite the increased concentration of atherogenic lipoproteins, enhanced atherogenesis is not characteristic of PBC. Serum total cholesterol, triglycerides, HDL2 and HDL3-cholesterol concentrations were measured by enzymatic methods or in combination with precipitation procedures. Apolipoproteins were determined by using immunonephelometric methods. ELISA sandwich method was used for lipoprotein(a) determinations. Apoprotein(a) phenotyping (isoforms) was performed by Western blotting with specific antibodies. The concentrations of serum lipids, lipoproteins and apoproteins (AI, AII and B) were found in the range of earlier investigations. The serum lipoprotein(a) concentration did not differ between the PBC patients and control subjects (10.0/0.1-54/, median 2.55 vs. 11.5/0-75/, median 5.2 mg/dl). In the advanced stages of PBC we found a higher number of patients with low lipoprotein concentration (lower than 1 mg/dl). In patients with shorter durations and milder histological alterations high HDL2 cholesterol subfractions has been detected (stage I = 0.42 +/- 0.18, stage II = 0.53 +/- 0.29 and stage III = 0.62 +/- 0.41 vs. stage IV = 0.26 +/- 0.15 mmol/l, P < 0.05). Despite the elevation of atherogenic lipoproteins, high HDL2-cholesterol and normal lipoprotein(a) concentrations may be one of the reasons why patients with advanced PBC are not placed at increased risk for atherosclerosis.

High lipoprotein(a) levels with predominance of high molecular weight apo(a) isoforms in patients with pulmonary embolism

Lipoprotein(a) (Lp(a)) may interact with the cellular components and protein co-factors of fibrinolysis. To evaluate the effect of Lp(a) in thromboembolic diseases of the venous system, we measured serum levels and the isoform distribution of apo(a) in 25 patients with pulmonary embolism (18 men, 7 women, aged 21-77 years). The control group was adjusted for sex and age (P = 0.189). Serum Lp(a) concentration was significantly higher in the study group (median: 9.3 vs. 4.3 mg dL-1). As the distribution of high and low molecular weight subtypes of apo(a) did not show any differences (P = 0.127) between the two groups, the elevated Lp(a) levels in patients with pulmonary embolism could not be attributed to the investigated kringle-4 polymorphism of the apo(a) gene and therefore other genetic or non-genetic implications are indicated.

Kringle 4 of human apolipoprotein[a] shares a linear antigenic site with human catalase

Monoclonal antibody (mab) 1A2, directed against human apolipoprotein[a] (apo[a]), revealed a strong reaction with peroxisomes as shown by immuno-gold labeled cryosections of human liver biopsies. This reactivity was not due to the presence of apo[a] in peroxisomes but to a cross-reactivity of mab 1A2. Immunoblot analysis of peroxisomal fractions and purified human catalase demonstrated that mab 1A2 reacts with catalase. Conversely, an anti-catalase antibody also recognized apo[a]. By sequence comparison we identified a 4-amino acid motif (Y-Y-P-N) that is shared between the highly repetitive kringle 4 motif of apo[a] and the carboxy-terminal third of the peroxisomal marker enzyme catalase. No other identical sequences were identified in these proteins. Results from the following experiments indicated that 1A2 recognizes this short linear epitope. i) Mab 1A2 reacted only with the 4 amino acid peptide sequence in a pin-ELISA using immobilized overlapping peptides. ii) A synthetic peptide including this sequence completely inhibited the 1A2 immunoreactivity to apo[a] and catalase. iii) A recombinant fusion protein tagged with the putative epitope was recognized by mab 1A2. Our findings demonstrate that unknown linear epitopes in native proteins can be identified by sequence comparison between known proteins. The practical implication is that antibodies against apo[a] must be controlled for this cross-reactivity before using them for immunohistochemical studies of intracellular apo[a] in tissues or cells.

Apolipoprotein A-IV polymorphism in the Hungarian population: gene frequencies, effect on lipid levels, and sequence of two new variants

The genetic polymorphism of human apolipoprotein A-IV was investigated in Hungarian blood donors (n = 202) by isoelectric focusing (IEF) of plasma samples followed by immunoblotting. The frequency of apo A-IV alleles was f(A-IV1) = 0.95, f(A-IV2) = 0.039 and f(A-IV3) = 0.002. This frequency distribution is significantly different from other Caucasian populations (P < 0.05). The association of apo A-IV phenotypes with HDL-cholesterol concentration which was previously described for two other European populations was only of borderline significance (P = 0.08). Three previously undescribed apo A-IV variants, designated Budapest-1, Budapest-2 and Budapest-3, were detected by IEF. The mutant proteins are not associated with alterations in the lipid/lipoprotein concentrations in heterozygotes. DNA-sequencing revealed two point mutations (Arg285-->Cys and Thr347-->Ser) in exon 3 of apo A-IV-Budapest-1 and a Glu-->Lys substitution at position 24 in exon 2 of apo A-IV-Budapest-2.

Plasma lipoprotein (a) concentration and phenotypes in diabetes mellitus

Patients with Type 1 (insulin-dependent) and Type 2 (non-insulin-dependent) diabetes mellitus are at increased risk of developing atherosclerotic vascular diseases. A variety of lipoprotein abnormalities have been described as being associated with this increased risk. In this study, apo(a) isoform frequencies and lipoprotein(a) [Lp(a)] concentrations were determined in Type 1 and Type 2 diabetic patients in order to investigate a possible contribution of Lp(a) to the increased risk for atherosclerosis in diabetes. No significant differences in plasma Lp(a) concentrations were found in two ethnically different populations (Austrians from the province of Tyrol and Hungarians from Budapest) in either type of diabetes when compared to respective control groups (91 Type 1 and 112 Type 2 diabetic patients vs 202 control subjects in the Hungarian study and 44 Type 1 diabetic and 44 Type 2 diabetic vs 125 control subjects in the Austrian study). There were also no significant apo(a) isoform frequency differences between both patient groups and control subjects in the two study groups. These data, obtained from two large ethnically different populations, provide no evidence of a contribution of Lp(a) to the increased risk for atherosclerosis in diabetes.

[Distribution of apolipoprotein A I and B in the blood according to age and gender, as well as their relation to blood cholesterol levels in the Hungarian blood donor population]

In this study we assessed the plasma CHOL, HDL cholesterol (HDL-C), apoprotein A I, apoprotein B levels and the polymorphic isoforms of apoprotein A I in Hungarian blood donors (n = 202, average age: 37.5 year). The mean values are presented for age and sex groups, and the data are compared to the international measurements. The mean CHOL concentration was 5.7 +/- 1.1 mmol/l. The CHOL level correlated with age and no significant association was observed with sex. The level of HDL-C showed no correlation with the age and--in opposite to the international data--there were no significant sex differences (women: 1.42 +/- 0.45, men: 1.34 +/- 0.44 mmol/l), which may be explained by the relative high HDL-C concentration of Hungarian men. Both apo A I and apo B showed an increase with advancing age. The only difference between the sexes was found in apoprotein A I levels, i. e. it was higher in women than in men (women: 156.3 +/- 23.6, men: 143.8 +/- 26.8 mg/dl). In contrary with the results from other countries, the apoprotein B concentrations in men did not differ from that measured in women (women: 72.1 +/- 17.4, men: 69 +/- 15.8 mg/dl). In relation to the age, in the fifth decade the CHOL, the HDL-C and the apo B levels were higher in women than in men.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of the apolipoprotein(a) size polymorphism on the lipoprotein(a) concentration in 7 ethnic groups

Apolipoprotein(a) [apo(a)] exhibits a genetic size polymorphism explaining about 40% of the variability in lipoprotein(a) [Lp(a)] concentration in Tyroleans. Lp(a) concentrations and apo(a) phenotypes were determined in 7 ethnic groups (Tyrolean, Icelandic, Hungarian, Malay, Chinese, Indian, Black Sudanese) and the effects of the apo(a) size polymorphism on Lp(a) levels were estimated in each group. Average Lp(a) concentrations were highly significantly different among these populations, with the Chinese (7.0 mg/dl) having the lowest and the Sudanese (46 mg/dl) the highest levels. Apo(a) phenotype and derived apo(a) allele frequencies were also significantly different among the populations. Apo(a) isoform effects on Lp(a) levels were not significantly different among populations. Lp(a) levels were however roughly twice as high in the same phenotypes in the Indians, and several times as high in the Sudanese, compared with Caucasians. The size variation of apo(a) explains from 0.77 (Malays) to only 0.19 (Sudanese) of the total variability in Lp(a) levels. Together these data show (I) that there is considerable heterogeneity of the Lp(a) polymorphism among populations, (II) that differences in apo(a) allele frequencies alone do not explain the differences in Lp(a) levels among populations and (III) that in some populations, e.g. Sudanese Blacks, Lp(a) levels are mainly determined by factors that are different from the apo(a) size polymorphism.