Antal Czinner

High prevalence of silent celiac disease in preschool children screened with IgA/IgG antiendomysium antibodies

BACKGROUND Because of the different sensitivity and specificity of serologic tests, the search for silent celiac disease is usually performed with the combined or sequential use of several tests. Among these, the IgA-class endomysium antibody test has the highest specificity and positive predictive value, but it may overlook IgA-deficient patients. METHODS To test a new one-step screening approach, serum samples from 427 apparently healthy, 3- to 6-year-old Hungarian children were investigated for IgA-class and IgG-class endomysium antibodies using monkey esophagus and human jejunum as substrates. RESULTS Five new cases with flat mucosa were identified by strong endomysium antibody positivity and subsequent jejunal biopsy, yielding a celiac disease prevalence of 1:85. An additional child may have latent celiac disease (slight histologic changes at present). Two of the screening-detected celiac patients exhibited only IgG-class endomysium antibodies due to associated IgA-deficiency. Despite the young age of the screened population, antigliadin antibodies were positive in only three of the five celiac patients. CONCLUSIONS Prevalence of celiac disease in the study population was much higher than expected on the basis of antigliadin antibody-based studies. The screening system used detected celiac cases in which there was IgA-deficiency and those in which there was not and also those negative for antigliadin antibodies. The findings suggest the importance of the primary testing of autoantibodies in future celiac disease screening policies.

Effect of Diet and Physical Exercise Treatment on Insulin Resistance Syndrome of Schoolchildren

Background: Insulin resistance syndrome (IRS) of schoolchildren may contribute to cardiovascular diseases (CVD) of young adults. The investigation of different steps, baseline screening parameters and treatment of IRS may help the prevention. Methods: Schoolchildren (53 boys and 61 girls age 5–17 years) because of adverse family history of CVD, hypertension, and obesity were investigated. Patients were divided into 3 groups according to baseline plasma glucose level (PGL) 120 and 180 min. after glucose consumption (GC): (1) PGL ≤ 5.5 mmol/L 180 min. after GC, (2) PGL ≥ 5.5 mmol/L 180 min. but ≤ 7.8 mmol/L 120 min. after GC (3) PGL ≥ 7.8 mmol/L 120 min. after GC. Body mass index (BMI), blood pressure (BP) and parameters of glucose and lipid metabolism were measured at baseline and after two years lifestyle modification. Results: No significant diference was found in the prevalence of cardiovascular risk factors (CRF) between groups 2 and 3. Fasting PGL > 5.5 mmol/L was found in 1, 2, and 6 cases; HOMA index > 4.4 in 7 (24%), 21 (37%), and 9 (35%) subjects; OGIS index < 400 in 3(10%), 29(51%) and 11 (42%) schoolchildren of groups 1, 2, 3, respectively. Lifestyle modification significantly improved BMI, systolic BP, serum triglyceride and HDL-cholesterol levels and insulin sensitivity. Conclusions: PGL measured 180 minutes after GC may define an important subgroup of pre-diabetic children. The similar prevalance of CRF in both praediabetic groups underlines the importance of this subgroup. Lifestyle modification for two years improves CRF in this population.

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

Abstract 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.

C112R, W323S, N317K mutations in the vasopressin V2 receptor gene in patients with nephrogenic diabetes insipidus

Hereditary hemmorrhagic telangiectasia (HHT) is an autosomal dominant disorder characterized by multisystemic vascular dyplasia and recurrent hemorrhage. One of the causative genes is the activin receptor-like kinase-1 (ALK-1) gene located on chromosome 12q13. ALK-1 is an endothelial cell type I receptor for the TGF-beta superfamily of ligands. As a number of mutations have been identified in the kinase domain of ALK-1, we initiated a mutation analysis specifically targeting the first four coding exons of ALK-1 in order to determine if mutations in the extracellular and transmembrane domains are also present in HHT. Six new mutations have been identified. Three frameshift mutations were identified in exons encoding the extracellular and transmembrane domains. These mutations would grossly truncate the ALK-1 protein and are thus classic null alleles. Three new missense mutations within the exons encoding the extracellular domain, in addition to two previously described missense mutations, are located at or near highly conserved cysteines. These mutations may disrupt intra- or inter-molecular disulfide bridges required for ligand binding. The combined data suggest that both severe and subtle changes in the ALK-1 amino acid sequence can lead to receptor dysfunction and result in the HHT disease phenotype.Marfan Syndrome (MfS) is an autosomal dominant inherited connective tissue disorder with variable phenotypic expression of cardiovascular, skeletal and ocular manifestations. Cardiovascular complications, such as aortic aneurysm and dissection drastically reduce life expectancy of individuals with MfS, whereas preventive surgery substantially improves the prognosis of these patients. A number of mutations in the fibrillin 1 (FBN1) gene associated with MfS have been identified to date, demonstrating considerable molecular heterogeneity. One region, however, located around exon 24, exhibits a striking clustering of mutations, which are associated with a severe, socalled neonatal form of MfS. Here we report the first mutation (G2950A) in exon 24 of the neonatal region of the FBN1 gene, associated with a classic MfS phenotype. The mutation leads to the subsitution of valin by isoleucin (V984I), both uncharged amino acids, which only differ in a single methyl group. This defect was identified in a proband with cardiovascular manifestations of MfS by SSCP analysis of PCR-amplified genomic DNA, direct PCR sequencing and RFLP analysis. The substitution was neither detected in the unaffected 4-year old daughter of the proband, nor in 3 of his healthy family members nor in 108 allels from control individuals, suggesting that this mutation is causative for MfS in the patient. Since no other family member of the proband is affected by MfS, the defect described is sporadic. In summary, we identified a novel defect in exon 24 of the neonatal region of the FBN1 gene in a patient with a classic phenotype of MfS, suggesting that conservative substitutions in this region may lead to a less severe phenotype of the disease. This finding further demonstrates the remarkable phenotypic heterogeneity associated with FBN1 mutations and stresses the significance of modifying genes and individual alterations in protein function for the pheontypic expression of the disease.Nephrogenic diabetes insipidus (NDI) is a rare, mostly X‐linked recessive disorder characterized by renal tubular resistance to the antidiuretic effect of arginine vasopressin. The gene responsible for the X‐linked NDI, the G‐protein‐coupled vasopressin V2 receptor, has been localized on the Xq28 region. In this study we present three NDI families from Hungary with three different missense mutations in the vasopressin V2 receptor gene. After the mutations in the affected probands in each family had been characterized, other family members were screened by restriction enzyme analysis. The N317K and the W323S mutations have not been detected previously. The C112R is an already known mutation. The N317K was a de novo mutation in the patient. The C112R and the W323S were found in the mothers of the patients as carriers and in all other patients, but not in the unaffected members of the families. Segregation of the mutations was consistent with the clinically observed symptoms as well as their severity. As conclusion, these findings provide further evidence that X‐linked NDI results from defects in the V2 receptor gene. Hum Mutat 12:137–138, 1998.

C112R, W323S, N317K mutations in the vasopressin V2 receptor gene in patients with nephrogenic diabetes insipidus. Mutations in brief no. 165. Online.

Hereditary hemmorrhagic telangiectasia (HHT) is an autosomal dominant disorder characterized by multisystemic vascular dyplasia and recurrent hemorrhage. One of the causative genes is the activin receptor-like kinase-1 (ALK-1) gene located on chromosome 12q13. ALK-1 is an endothelial cell type I receptor for the TGF-beta superfamily of ligands. As a number of mutations have been identified in the kinase domain of ALK-1, we initiated a mutation analysis specifically targeting the first four coding exons of ALK-1 in order to determine if mutations in the extracellular and transmembrane domains are also present in HHT. Six new mutations have been identified. Three frameshift mutations were identified in exons encoding the extracellular and transmembrane domains. These mutations would grossly truncate the ALK-1 protein and are thus classic null alleles. Three new missense mutations within the exons encoding the extracellular domain, in addition to two previously described missense mutations, are located at or near highly conserved cysteines. These mutations may disrupt intra- or inter-molecular disulfide bridges required for ligand binding. The combined data suggest that both severe and subtle changes in the ALK-1 amino acid sequence can lead to receptor dysfunction and result in the HHT disease phenotype.Marfan Syndrome (MfS) is an autosomal dominant inherited connective tissue disorder with variable phenotypic expression of cardiovascular, skeletal and ocular manifestations. Cardiovascular complications, such as aortic aneurysm and dissection drastically reduce life expectancy of individuals with MfS, whereas preventive surgery substantially improves the prognosis of these patients. A number of mutations in the fibrillin 1 (FBN1) gene associated with MfS have been identified to date, demonstrating considerable molecular heterogeneity. One region, however, located around exon 24, exhibits a striking clustering of mutations, which are associated with a severe, socalled neonatal form of MfS. Here we report the first mutation (G2950A) in exon 24 of the neonatal region of the FBN1 gene, associated with a classic MfS phenotype. The mutation leads to the subsitution of valin by isoleucin (V984I), both uncharged amino acids, which only differ in a single methyl group. This defect was identified in a proband with cardiovascular manifestations of MfS by SSCP analysis of PCR-amplified genomic DNA, direct PCR sequencing and RFLP analysis. The substitution was neither detected in the unaffected 4-year old daughter of the proband, nor in 3 of his healthy family members nor in 108 allels from control individuals, suggesting that this mutation is causative for MfS in the patient. Since no other family member of the proband is affected by MfS, the defect described is sporadic. In summary, we identified a novel defect in exon 24 of the neonatal region of the FBN1 gene in a patient with a classic phenotype of MfS, suggesting that conservative substitutions in this region may lead to a less severe phenotype of the disease. This finding further demonstrates the remarkable phenotypic heterogeneity associated with FBN1 mutations and stresses the significance of modifying genes and individual alterations in protein function for the pheontypic expression of the disease.Nephrogenic diabetes insipidus (NDI) is a rare, mostly X‐linked recessive disorder characterized by renal tubular resistance to the antidiuretic effect of arginine vasopressin. The gene responsible for the X‐linked NDI, the G‐protein‐coupled vasopressin V2 receptor, has been localized on the Xq28 region. In this study we present three NDI families from Hungary with three different missense mutations in the vasopressin V2 receptor gene. After the mutations in the affected probands in each family had been characterized, other family members were screened by restriction enzyme analysis. The N317K and the W323S mutations have not been detected previously. The C112R is an already known mutation. The N317K was a de novo mutation in the patient. The C112R and the W323S were found in the mothers of the patients as carriers and in all other patients, but not in the unaffected members of the families. Segregation of the mutations was consistent with the clinically observed symptoms as well as their severity. As conclusion, these findings provide further evidence that X‐linked NDI results from defects in the V2 receptor gene. Hum Mutat 12:137–138, 1998.

Apolipoprotein A-IV and E Polymorphisms in Children With IDDM

Premixed insulins (e.g., Actraphane) are best avoided because of the likely risk of hypoglycemia in the afternoon (6). Insulin-requiring type 2 diabetic patients should follow the same regimen as outlined for type 1 diabetic patients (5). Home blood glucose monitoring, which is now regarded as an important prerequisite in the management of insulintreated diabetic patients, should be mandatory in those insulin-treated patients who wish to fast. This way, a close watch could be kept on overall control, as well as on hypoglycemic episodes that may require adjustments to insulin dose or termination of the fast. Diabetic patients should be advised that neither the pinprick required to do home blood glucose monitoring nor injecting oneself with insulin will break the fast (5,6). During Ramadan, control should continue to be assessed on the basis of home blood glucose monitoring, as well as clinicbased tests. Investigation should be made of hypoglycemic episodes or very high blood glucose levels, and appropriate dose adjustments should be made or the patient may be advised to discontinue fasting. After Ramadan, the patients therapeutic regimen will need to be changed back to what it was previously. An overall evaluation will also be required.

Genetic investigation of patients with hypercholesterolemia type IIa.

To the Editor: Hypercholesterolemia is one of the most frequent disorders in Hungary with a complex, mostly unknown genetic background. Several factors can influence cholesterol levels. Three important genetic factors are polymorphisms in the apolipoprotein (apo) E gene, mutations in the apoB and low density lipoprotein (LDL) receptor genes. In our study we investigated the apoE, apoB and LDL receptor genes in 210 (100 male, 110 female, age 12–65 (52.5918.6) years) unrelated Hungarian hypercholesterolemic patients with hypercholesterolemia type IIa. Isotypings of apoE were carried out by DNA amplification and digestion with HhaI as proposed by Hixson (1). The receptor binding domain of apoB-100 was investigated by allele-specific and asymmetric polymerase chain reaction (PCR) as proposed by Schuster (2). Exon 4a of the LDL receptor gene was amplified by PCR with the oligonucleotide primers proposed by Hobbs (3). The single strand conformation polymorphism (SSCP) analysis of the exon 4a of the LDL receptor gene and the amplified apoB fragments was carried out in the PhastSystemTM automated electrophoresis system (Pharmacia LKB, Uppsala, Sweden). The samples were screened for familial hypercholesterolemia (FH)Elverum and FH-Helsinki as proposed by Leren (4) and Aalto-Setälä (5), respectively. Calculated allele frequencies of 6.4 for apoE2, 79.3 for apoE3, and 14.3% for apoE4 were seen with no significant difference between the frequency of apoE genotypes in patients with hypercholesterolemia and in the general population in Hungary (6). The apoE genotype distribution was in Hardy–Weinberg equilibrium. The total cholesterol values did not vary significantly among the genotype groups. These findings suggest that apoE isoforms do not play an important role in hypercholesterolemia type IIa and do not influence sig-

Frequency of the HIV-1 resistance CCR5 deletion allele in Hungarian newborns.

Sir: The b-chemokine receptor 5 (CCR5) has recently been shown to be a major coreceptor for entry of human immunode®ciency virus-1 (HIV-1)[2]. A 32 base-pair (bp) deletion in the CCR5 coding region results in a non-functional receptor. Homozygotes for the mutation are resistant to infection, even after repeated high-risk exposure [1]. This allele is common in the Caucasian population with a frequency of 0.0808 but was not found in people of African or Asian ancestry [3, 4]. We have carried out a genetic screening in 108 healthy Hungarian newborns for the frequency of the CCR5D32 allele. Ampli®cation of DNA was performed by PCR, using the CCR5-speci®c primer pair (F: 5¢-CTTCATTACACCTG-3¢; R: 5¢CACAGCCCTGTGCCTCTTCTTCTCA-3¢) which ̄anks the 32 bp deletion, and separated in 4% agarose gel, stained with ethidium bromide. Among the 108 newborn samples tested, 21 were heterozygous and 2 homozygous for the 32 bp deletion, yielding a calculated allele frequency of 0.116 in Hungary. The results are in HardyWeinberg equilibrium which predicts frequencies of 0.781 wild type homozygotes, 0.205 heterozygotes, and 0.014 homozygotes for the deleted CCR5 in the Hungarian population. The HIV-1 resistance allele, or deletion mutant of the CCR5 gene is not distributed equally among the worlds people [4]. So far it has not been found in African and Eastern Asian populations and in native Americans. Even among Caucasians the distribution varies. The frequency is high in the northern part of Europe (e.g. in Sweden 0.137, in Poland 0.133 and in England 0.113), lower in Central Europe (e.g. in Austria 0.083), even lower in South Europe (e.g. in Italy 0.055, in Greece 0.044). It is suspected that the mutant allele is a consequence of a major epidemic about 1200±4300 years ago in the northern part of Europe caused by an agent that, like HIV, makes use of the normal CCR5 protein, but not the defective form, to infect cells. The epidemic gave originally rare individuals who harboured the mutation a dramatic survival advantage. Hungarians, originating in part from a region of the Ural Mountains, have been living in Central Europe since 896 AD. The frequency of the mutant allele is slightly higher in the Hungarian population (0.116) than in the neighbouring countries (in Austria 0.083 or in Slovakia 0.077), and more similar to the allele frequency in Germany (0.108).