Genetic counselling legislation and practice in cancer in EU Member States.

BACKGROUND: Somatic and germline genetic alterations are significant drivers of cancer. Increasing integration of new technologies which profile these alterations requires timely, equitable and high-quality genetic counselling to facilitate accurate diagnoses and informed decision-making by patients and their families in preventive and clinical settings. This article aims to provide an overview of genetic counselling legislation and practice across European Union (EU) Member States to serve as a foundation for future European recommendations and action. METHODS: National legislative databases of all 27 Member States were searched using terms relevant to genetic counselling, translated as appropriate. Interviews with relevant experts from each Member State were conducted to validate legislative search results and provide detailed insights into genetic counselling practice in each country. RESULTS: Genetic counselling is included in national legislative documents of 22 of 27 Member States, with substantial variation in legal mechanisms and prescribed details (i.e. the 'who, what, when and where' of counselling). Practice is similarly varied. Workforce capacity (25 of 27 Member States) and genetic literacy (all Member States) were common reported barriers. Recognition and/or better integration of genetic counsellors and updated legislation and were most commonly noted as the 'most important change' which would improve practice. CONCLUSIONS: This review highlights substantial variability in genetic counselling across EU Member States, as well as common barriers notwithstanding this variation. Future recommendations and action should focus on addressing literacy and capacity challenges through legislative, regulatory and/or strategic approaches at EU, national, regional and/or local levels.

Double Heterozygosity for Rare Deleterious Variants in the BRCA1 and BRCA2 Genes in a Hungarian Patient with Breast Cancer.

Hereditary breast cancer is most commonly attributed to germline BRCA1 and BRCA2 gene variants. The vast majority of BRCA1 and BRCA2 mutation carriers are single heterozygotes, and double heterozygosity (DH) is a very rare finding. Here, we describe the case of a BRCA1/BRCA2 double heterozygous female proband diagnosed with breast cancer. Genetic testing for hereditary breast and ovarian cancer revealed two pathogenic variants in the BRCA1 (c.5095C>T, p.(Arg1699Trp)) and in BRCA2 genes (c.658_659delGT, p.(Val220Ilefs*4)) in heterozygous form. None of the variants were founder Jewish mutations; to our knowledge, these rare deleterious variants have not been previously described in DH patients in the literature. The patient had triple-negative unilateral breast cancer at the age of 36 and 44 years. Based on family studies, the BRCA1 variant was maternally inherited.

[Genetic revision of the Hungarian Cystic Fibrosis Registry]. / A magyar Cystás Fibrosis Regiszter genetikai revíziója.

INTRODUCTION: Cystic fibrosis (CF) is one of the most common monogenic diseases. Genetic testing is becoming increasingly reasoned to establish or confirm the diagnosis by detecting abnormal mutations. OBJECTIVE: In order to develop a diagnostic strategy for cystic fibrosis and to facilitate mutation-specific treatments, the genetic revision of the Hungarian Cystic Fibrosis Registry was performed. METHOD: 582 patients' data and samples were used for the revision (528 originally included in the register and 54 received during the revision). First we reviewed the patients' existing genetic findings. Wherever necessary, a comprehensive three-level genetic analysis of the CFTR gene was done. RESULTS: According to our study, of the 528 patients present in the Registry, 395 (74.8%) had 2 pathogenic CFTR mutations. We completed and corrected 94 patients' previously incomplete genetic status. 73 different pathogenic variants were described, in which 1 aberration was not previously reported (c.3130G>A). The 5 most common mutations were: F508del (68.4%); CFTRdele2,3 (3.7%); G542X (3.2%); 2184insA (2.7%); W1282X (2.3%). Based on genotype and age, in Hungary 211 patients are eligible for the available lumacaftor-ivacaftor combination therapy, and 361 patients for the ivacaftor-tezacaftor-elexacaftor therapy. CONCLUSION: Due to the revision, we could identify the patients who can benefit from mutation-specific drugs instead of symptomatic therapy. In addition, the data obtained have been used to map the Hungarian distribution of mutations in the CFTR gene, which will help to develop a diagnostic strategy. Orv Hetil. 2022; 163(51): 2052-2059.

Helsmoortel-Van der Aa Syndrome-Cardiothoracic and Ectodermal Manifestations in Two Patients as Further Support of a Previous Observation on Phenotypic Overlap with RASopathies.

The ADNP-gene-related neurodevelopmental disorder Helsmoortel-Van der Aa syndrome is a rare syndromic-intellectual disability-an autism spectrum disorder first described by Helsmoortel and Van der Aa in 2014. Recently, a large cohort including 78 patients and their detailed phenotypes were presented by Van Dijck et al., 2019, who reported developmental delay, speech delay and autism spectrum disorder as nearly constant findings with or without variable cardiological, gastroenterological, urogenital, endocrine and neurological manifestations. Among cardiac malformations, atrial septal defect, patent ductus arteriosus, patent foramen ovale and mitral valve prolapse were the most common findings, but other unspecified defects, such as mild pulmonary valve stenosis, were also described. We present two patients with pathogenic ADNP variants and unusual cardiothoracic manifestations-Bland-White-Garland syndrome, pectus carinatum superiorly along the costochondral junctions and pectus excavatum inferiorly in one patient, and Kawasaki syndrome with pericardiac effusion, coronary artery dilatation and aneurysm in the other-who were successfully treated with intravenous immunoglobulin, corticosteroid and aspirin. Both patients had ectodermal and/or skeletal features overlapping those seen in RASopathies, supporting the observations of Alkhunaizi et al. 2018. on the clinical overlap between Helsmoortel-Van der Aa syndrome and Noonan syndrome. We observed a morphological overlap with the Noonan-like disorder with anagen hair in our patients.

An Ultra-Rare Manifestation of an X-Linked Recessive Disorder: Duchenne Muscular Dystrophy in a Female Patient.

Duchenne muscular dystrophy (DMD) is the most common inherited muscle dystrophy. Patients are characterized by muscle weakness, gross motor delay, and elevated serum creatinine kinase (CK) levels. The disease is caused by mutations in the DMD gene located on the X chromosome. Due to the X-linked recessive inheritance pattern, DMD most commonly affects males, who are generally diagnosed between the age of 3-5 years. Here we present an ultra-rare manifestation of DMD in a female patient. Cytogenetic examination showed that she has a t(X;10)(p21.1;p12.1) translocation, which turned out to affect the DMD gene with one of the breakpoints located in exon 54 (detected by genome sequencing). The X-inactivation test revealed skewed X-inactivation (ratio 99:1). Muscle histology and dystrophin immunohistochemistry showed severe dystrophic changes and highly reduced dystrophin expression, respectively. These results, in accordance with the clinical picture and a highly elevated serum CK, led to the diagnosis of DMD. In conclusion, although in very rare cases, DMD can manifest in female patients as well. In this case, a balanced X-autosome reciprocal translocation disrupts the DMD gene and skewed X-inactivation leads to the manifestation of the DMD phenotype.

Cytogenetic Investigation of Infertile Patients in Hungary: A 10-Year Retrospective Study.

Chromosome abnormalities play a crucial role in reproductive failure. The presence of numerical or structural aberrations may induce recurrent pregnancy loss or primary infertility. The main purpose of our study was to determine the types and frequency of chromosomal aberrations in infertile patients and to compare the frequency of structural aberrations to a control group. Karyotyping was performed in 1489 men and 780 women diagnosed with reproductive failure between 2010 and 2020. The control group included 869 male and 1160 female patients having cytogenetic evaluations for reasons other than infertility. Sex chromosomal aberrations were detected in 33/1489 (2.22%) infertile men and 3/780 (0.38%) infertile women. Structural abnormalities (e.g., translocation, inversion) were observed in 89/1489 (5.98%) infertile men and 58/780 (7.44%) infertile women. The control population showed structural chromosomal abnormalities in 27/869 (3.11%) men and 39/1160 (3.36%) women. There were significant differences in the prevalence of single-cell translocations between infertile individuals (males: 3.5%; females: 3.46%) and control patients (males: 0.46%; females: 0.7%). In summary, this is the first report of cytogenetic alterations in infertile patients in Hungary. The types of chromosomal abnormalities were comparable to previously published data. The prevalence of less-studied single-cell translocations was significantly higher in infertile patients than in the control population, supporting an earlier suggestion that these aberrations may be causally related to infertility.

Biochemical and Clinical Effects of Vitamin E Supplementation in Hungarian Smith-Lemli-Opitz Syndrome Patients.

Smith-Lemli-Opitz syndrome (SLOS) is a severe monogenic disorder resulting in low cholesterol and high 7-dehydrocholesterol (7-DHC) levels. 7-DHC-derived oxysterols likely contribute to disease pathophysiology, and thus antioxidant treatment might be beneficial because of high oxidative stress. In a three-year prospective study, we investigated the effects of vitamin E supplementation in six SLOS patients already receiving dietary cholesterol treatment. Plasma vitamin A and E concentrations were determined by the high-performance liquid chromatography (HPLC) method. At baseline, plasma 7-DHC, 8-dehydrocholesterol (8-DHC) and cholesterol levels were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. The clinical effect of the supplementation was assessed by performing structured parental interviews. At baseline, patients were characterized by low or low-normal plasma vitamin E concentrations (7.19-15.68 µmol/L), while vitamin A concentrations were found to be normal or high (1.26-2.68 µmol/L). Vitamin E supplementation resulted in correction or significant elevation of plasma vitamin E concentration in all patients. We observed reduced aggression, self-injury, irritability, hyperactivity, attention deficit, repetitive behavior, sleep disturbance, skin photosensitivity and/or eczema in 3/6 patients, with notable individual variability. Clinical response to therapy was associated with a low baseline 7-DHC + 8-DHC/cholesterol ratio (0.2-0.4). We suggest that determination of vitamin E status is important in SLOS patients. Supplementation of vitamin E should be considered and might be beneficial.

Interaction of maternal immune activation and genetic interneuronal inhibition.

Genes and environment interact during intrauterine life, and potentially alter the developmental trajectory of the brain. This can result in life-long consequences on brain function. We have previously developed two transgenic mouse lines that suppress Gad1 expression in parvalbumin (PVALB) and neuropeptide Y (NPY) expressing interneuron populations using a bacterial artificial chromosome (BAC)-driven miRNA-based silencing technology. We were interested to assess if maternal immune activation (MIA), genetic interneuronal inhibition, and the combination of these two factors disrupt and result in long-term changes in neuroinflammatory gene expression, sterol biosynthesis, and acylcarnitine levels in the brain of maternally exposed offspring. Pregnant female WT mice were given a single intraperitoneal injection of saline or polyinosinic-polycytidilic acid [poly(I:C)] at E12.5. Brains of offspring were analyzed at postnatal day 90. We identified complex and persistent neuroinflammatory gene expression changes in the hippocampi of MIA-exposed offspring, as well in the hippocampi of Npy/Gad1 and Pvalb/Gad1 mice. In addition, both MIA and genetic inhibition altered the post-lanosterol sterol biosynthesis in the neocortex and disrupted the typical acylcarnitine profile. In conclusion, our findings suggest that both MIA and inhibition of interneuronal function have long-term consequences on critical homeostatic mechanisms of the brain, including immune function, sterol levels, and energy metabolism.

FBN1 gene mutations in 26 Hungarian patients with suspected Marfan syndrome or related fibrillinopathies.

Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder mainly affecting the cardiovascular, ocular and musculo-skeletal systems. FBN1 gene mutations lead to MFS and related connective tissue disorders. In this work we described clinical and molecular data of 26 unrelated individuals with suspected MFS who were referred for FBN1 mutation analysis. FBN1 gene sequencing was performed by next generation sequencing and Sanger sequencing methods. We identified 23 causal or potentially causal (including variants of uncertain significance) FBN1 variants, seven of them was novel (˜30%). About 30% of the cases were sporadic. FBN1 mutations were associated with MFS in the majority of the patients, in two cases with severe and early onset manifestation of the syndrome. Missense mutations were detected in 69.6% (16/23), the majority of them were located in one of the cbEGF motifs and ˜70% of them substituted conserved cystein residues. Small deletions/duplications were identified in 13% of the cases (3/23), while splice site variants were detected in 17.4% (4/23). In three unrelated patients a low frequency recurrent silent variant (c.3294C > T (p.Asp1098=) was identified. FBN1 mRNA analysis showed that the mutation does not lead to aberrant splicing, based on available data the mutation was classified as benign.

Subcellular localization of sterol biosynthesis enzymes.

Cholesterol synthesis is a complex, coordinated process involving a series of enzymes. As of today, our understanding of subcellular localization of cholesterol biosynthesis enzymes is far from complete. Considering the complexity and intricacies of this pathway and the importance of functions of DHCR7, DHCR24 and EBP enzymes for human health, we undertook a study to determine their subcellular localization and co-localization. Using expression constructs and antibody staining in cell cultures and transgenic mice, we found that all three enzymes are expressed in ER and nuclear envelope. However, their co-localization was considerably different across the cellular compartments. Furthermore, we observed that in the absence of DHCR7 protein, DHCR24 shows a compensatory upregulation in a Dhcr7-/- transgenic mouse model. The overall findings suggest that the sterol biosynthesis enzymes might not always work in a same functional complex, but that they potentially have different, multifunctional roles that go beyond the sterol biosynthesis pathway. Furthermore, the newly uncovered compensatory mechanism between DHCR7 and DHCR24 could be of importance for designing medications that would improve cholesterol production in patients with desmosterolosis and Smith-Lemli-Opitz syndrome.

Interfering effect of maternal cell contamination on invasive prenatal molecular genetic testing.

OBJECTIVE: Fetal samples obtained by invasive techniques are prone to maternal cell contamination (MCC), which may lead to false genotyping results. Our aim was to determine 3 molecular genetic tests' sensitivity to MCC. METHOD: By mixing experiments, 1%, 5%, 10%, 20%, 30%, and 40% MCC was simulated, and significant MCC levels were determined for Sanger DNA sequencing, multiplex ligation-dependent probe amplification (MLPA), and pyrosequencing, a next-generation sequencing method. RESULTS: For Sanger sequencing, the limit of sensitivity to MCC was 5% to 30%. For MLPA, a higher proportion of MCC (≥40%) was shown to lead to diagnostic uncertainty. In contrast, pyrosequencing proved to be very sensitive to MCC, detecting a proportion as low as 1%. CONCLUSION: In the case of Sanger sequencing, sensitivity to MCC was variable, while for MLPA, only high levels of MCC proved to be significant. Although the next-generation sequencing method was sensitive to low-level MCC, if MCC level is determined in parallel, accurate quantification of allelic ratios can help to interpret the diagnostic results. Knowledge of significant MCC levels allows correct prenatal diagnosis even if samples are not purely of fetal origin and repeated sampling can be avoided in many of the cases.

Analytical parameters and validation of homopolymer detection in a pyrosequencing-based next generation sequencing system.

BACKGROUND: Current technologies in next-generation sequencing are offering high throughput reads at low costs, but still suffer from various sequencing errors. Although pyro- and ion semiconductor sequencing both have the advantage of delivering long and high quality reads, problems might occur when sequencing homopolymer-containing regions, since the repeating identical bases are going to incorporate during the same synthesis cycle, which leads to uncertainty in base calling. The aim of this study was to evaluate the analytical performance of a pyrosequencing-based next-generation sequencing system in detecting homopolymer sequences using homopolymer-preintegrated plasmid constructs and human DNA samples originating from patients with cystic fibrosis. RESULTS: In the plasmid system average correct genotyping was 95.8% in 4-mers, 87.4% in 5-mers and 72.1% in 6-mers. Despite the experienced low genotyping accuracy in 5- and 6-mers, it was possible to generate amplicons with more than a 90% adequate detection rate in every homopolymer tract. When homopolymers in the CFTR gene were sequenced average accuracy was 89.3%, but varied in a wide range (52.2 - 99.1%). In all but one case, an optimal amplicon-sequencing primer combination could be identified. In that single case (7A tract in exon 14 (c.2046_2052)), none of the tested primer sets produced the required analytical performance. CONCLUSIONS: Our results show that pyrosequencing is the most reliable in case of 4-mers and as homopolymer length gradually increases, accuracy deteriorates. With careful primer selection, the NGS system was able to correctly genotype all but one of the homopolymers in the CFTR gene. In conclusion, we configured a plasmid test system that can be used to assess genotyping accuracy of NGS devices and developed an accurate NGS assay for the molecular diagnosis of CF using self-designed primers for amplification and sequencing.

A novel point mutation affecting Asn76 of dystrophin protein leads to dystrophinopathy.

Mutations in the DMD gene lead to Duchenne and Becker muscular dystrophy (DMD/BMD). Missense mutations are rare cause of DMD/BMD. A six-month-old male patient presented with mild generalized muscle weakness, hypotonia, and delayed motor development. Dystrophinopathy was suspected because of highly elevated serum creatine kinase level (1497 U/L) and tiered DMD gene analysis was performed. Multiplex ligation-dependent probe amplification (MLPA) assay showed deletion of exon 4, which could not be confirmed by another method. Sequencing of exon 4 revealed a novel de novo point mutation (c.227A>T, p.Asn76Ile) in the N-terminal actin-binding domain (N-ABD) of dystrophin protein. The false positive MLPA result was explained by the fact that the affected nucleotide lies directly at the 3' ligation site of the MLPA probe. Sequencing of the whole coding region of DMD gene proved c.227A>T to be the sole variant being potentially pathogenic. According to in silico analyses the mutation was predicted to be highly destabilizing on N-ABD structure possibly leading to protein malfunction. Muscle biopsy was performed and dystrophin immunohistochemistry results were suggestive of BMD. Our results highlight the importance of confirmatory testing of single-exon deletions detected by MLPA and we describe a novel, destabilizing missense mutation in the DMD gene.

Vulnerability of DHCR7+/- mutation carriers to aripiprazole and trazodone exposure.

Smith-Lemli-Opitz syndrome is a recessive disorder caused by mutations in 7-dehydrocholesterol reductase (DHCR)7 with a heterozygous (HET) carrier frequency of 1-3%. A defective DHCR7 causes accumulation of 7-dehydrocholesterol (DHC), which is a highly oxidizable and toxic compound. Recent studies suggest that several antipsychotics, including the highly prescribed pharmaceuticals, aripiprazole (ARI) and trazodone (TRZ), increase 7-DHC levels in vitro and in humans. Our investigation was designed to compare the effects of ARI and TRZ on cholesterol (Chol) synthesis in fibroblasts from DHCR7+/- human carriers and controls (CTRs). Six matched pairs of fibroblasts were treated and their sterol profile analyzed by LC-MS. Significantly, upon treatment with ARI and TRZ, the total accumulation of 7-DHC was higher in DHCR7-HET cells than in CTR fibroblasts. The same set of experiments was repeated in the presence of 13C-lanosterol to determine residual Chol synthesis, revealing that ARI and TRZ strongly inhibit de novo Chol biosynthesis. The results suggest that DHCR7 carriers have increased vulnerability to both ARI and TRZ exposure compared with CTRs. Thus, the 1-3% of the population who are DHCR7 carriers may be more likely to sustain deleterious health consequences on exposure to compounds like ARI and TRZ that increase levels of 7-DHC, especially during brain development.

The Effect of Small Molecules on Sterol Homeostasis: Measuring 7-Dehydrocholesterol in Dhcr7-Deficient Neuro2a Cells and Human Fibroblasts.

Well-established cell culture models were combined with new analytical methods to assess the effects of small molecules on the cholesterol biosynthesis pathway. The analytical protocol, which is based on sterol derivation with the dienolphile PTAD, was found to be reliable for the analysis of 7-DHC and desmosterol. The PTAD method was applied to the screening of a small library of pharmacologically active substances, and the effect of compounds on the cholesterol pathway was determined. Of some 727 compounds, over 30 compounds decreased 7-DHC in Dhcr7-deficient Neuro2a cells. The examination of chemical structures of active molecules in the screen grouped the compounds into distinct categories. In addition to statins, our screen found that SERMs, antifungals, and several antipsychotic medications reduced levels of 7-DHC. The activities of selected compounds were verified in human fibroblasts derived from Smith-Lemli-Opitz syndrome (SLOS) patients and linked to specific transformations in the cholesterol biosynthesis pathway.

[Inborn error of cholesterol biosynthesis: Smith-Lemli-Opitz syndrome]. / A koleszterin-bioszintézis veleszületett zavara: a Smith-Lemli-Opitz-szindróma.

Smith-Lemli-Opitz syndrome is an autosomal recessive mental retardation and multiple malformation syndrome caused by deficiency of the 7-dehydrocholesterol reductase, the enzyme catalyzing the last step in cholesterol biosynthesis. The authors summarize the pathophysiology, epidemiology, clinical picture, diagnostics and therapy of the disease based on a review of the international literature. Since 2004, fourteen patients have been diagnosed with Smith-Lemli-Opitz syndrome in Hungary, which suggests an underdiagnosis of the disease based upon estimated incidence data. Due to deficiency of the 7-dehydrocholesterol reductase, serum cholesterol concentration is low and 7-dehydrocholesterol concentration is elevated in blood and tissues; the latter being highly specific for the syndrome. Detection of disease-causing mutations makes the prenatal diagnosis possible. The clinical spectrum is wide, the most common symptom is syndactyly of the second and third toes. Standard therapy is cholesterol supplementation. Recent publications suggest that oxidative compounds of 7-dehydrocholesterol may play a role in the pathophysiology of the disease as well.

Molecular Analysis of Cystic Fibrosis Patients in Hungary - An Update to the Mutational Spectrum.

BACKGROUND: In this study the authors present an update to the CFTR mutation profile in Hungary, utilizing data from a selected cohort of 45 cystic fibrosis (CF) patients from different regions of the country. METHODS: Depending on the preceding analysis, four different mutation detection methods were used. A commercial assay targeting the most common CF-causing mutations was performed as the first test followed by an allele specific PCR for CFTRdele2,3(21kb), Sanger sequencing and MLPA analysis of the coding region of the CFTR gene. RESULTS: In our recent study 27 different mutations were detected, including 2 novel ones (c.1037_1038insA and c.1394C>T). Besides F508del (c.1521_1523delCTT), the following mutations were found at a frequency of ≥ 4.0%: W1282X (c.3846G>A), N1303K (c.3909C>G), CFTRdele2,3(21kb) (c.54-5940_273+10250del21kb) and 2184insA (c.2052_2053insA). In addition, four mutations (G542X, Y1092X, 621+1G>T, and 2143delT) were found in more than one allele. CONCLUSIONS: The updated database of Hungarian mutations not only enables to increase the efficiency of the existing diagnostic approach, but also provides a further refined basis for the introduction of the molecular newborn screening (NBS) program in Hungary.

Detection of internal tandem duplications in the FLT3 gene by different electrophoretic methods.

BACKGROUND: In acute myeloid leukemia (AML), the internal tandem duplication (ITD) in the juxtamembrane domain of the FLT3 (Fms-like tyrosine kinase 3) gene is one of the most frequent genetic alterations associated with poor prognosis. METHODS: A complex evaluation of the analytical properties of the three most frequently used detection methods--PCR followed by agarose (AGE), polyacrylamide (PAGE) or capillary electrophoresis (CE)--was performed on 95 DNA samples obtained from 73 AML patients. RESULTS: All the three methods verified the presence of a mutant allele in 20 samples from 18 patients. AGE and PAGE could detect the presence of 1%-2% mutant allele, while the detection limit of CE was 0.28%. However, acceptable reproducibility (inter-assay CV <25%) of the mutant allele rate determination was only achievable above 1.5% mutant/total allele rate. The reproducibility of the ITD size determination by CE was much better, but the ITD size calculated by PeakScanner or GeneScan analysis was 7% lower as compared to values obtained by DNA sequencing. The presence of multiple ITD was over-estimated by PAGE and AGE due to the formation of heteroduplexes. CONCLUSIONS: This study suggests the use of PCR+CE in the diagnostics and the follow-up of AML patients. The data further supports the importance of proper analytical evaluation of home-made molecular biological diagnostic tests.

Autoantibodies to novel membrane and cytosolic antigens of the lachrymal gland in primary Sjögren's syndrome.

Sjögren's syndrome (SS) is a prototypical systemic autoimmune disease, where autoimmune processes lead to the dysfunction of the exocrine glands. The key feature of the disease is autoimmune exocrinopathy, causing reduced tear secretion and subsequent keratoconjunctivitis sicca (KCS). The aim of this study was to investigate the connection between the presence of autoantibodies to lachrymal gland antigens and the reduced tear production in patients with primary SS. Ninety-nine patients, 90 women and 9 men, were investigated in the study. Twenty healthy young women served as controls. Enzyme-linked immunosorbent assay (ELISA) and Western blotting were applied to detect autoantibodies to antigen fractions prepared from the human lachrymal gland membrane and cytosolic fractions. Autoantibodies of the IgG, IgA and IgM isotypes to the lachrymal membrane and cytosolic fractions were detected in about one third (27%) of the patients with primary SS. IgA antobodies to the membrane and cytosolic fractions occurred most frequently in SS patients. A significant difference was found in the presence of IgA antibodies to the membrane lachrymal fraction between patients and controls given in ELISA indices (1.23 +/- 0.3 vs 1 +/- 0.19, p < 0.001). IgG, IgA, and IgM isotypes of autoantibodies directed to the membrane lachrymal fraction of 200-180, 120-116, 80-70, 58, 50, 48.5, 40 and 28.8 kDa were also identified in patients. Membrane IgG antibody levels showed a positive correlation (R = 0.998; p = 0.045) with the clinical loss of secretory function (Schirmer's test values). Positive correlation was found between membrane IgM and anti-SS-A levels (R = 0.962; p = 0.038) and also between cytosolic IgM antibodies and anti-SS-A levels (R = 0.982; p = 0.018). IgG, IgA and IgM types of autoantibodies may play a role in the development of the impaired lachrymal secretion and therefore may be involved in the pathogenesis of KCS.