Combined Analysis of Methylation and Gene Expression Profiles in Separate Compartments of Small Bowel Mucosa Identified Celiac Disease Patients' Signatures

By GWAS studies on celiac disease, gene expression was studied at the level of the whole intestinal mucosa, composed by two different compartments: epithelium and lamina propria. Our aim is to analyse the gene-expression and DNA methylation of candidate genes in each of these compartments. Epithelium was separated from lamina propria in biopsies of CeD patients and CTRs using magnetic beads. Gene-expression was analysed by RT-PC; methylation analysis required bisulfite conversion and NGS. Reverse modulation of gene-expression and methylation in the same cellular compartment was observed for the IL21 and SH2B3 genes in CeD patients relative to CTRs. Bioinformatics analysis highlighted the regulatory elements in the genomic region of SH2B3 that altered methylation levels. The cREL and TNFAIP3 genes showed methylation patterns that were significantly different between CeD patients and CTRs. In CeD, the genes linked to inflammatory processes are up-regulated, whereas the genes involved in the cell adhesion/integrity of the intestinal barrier are down-regulated. These findings suggest a correlation between gene-expression and methylation profile for the IL21 and SH2B3 genes. We identified a “gene-expression phenotype” of CeD and showed that the abnormal response to dietary antigens in CeD might be related not to abnormalities of gene structure but to the regulation of molecular pathways.

Concentrations of urinary arsenic species in relation to rice and seafood consumption among children living in Spain

Inorganic arsenic (i-As) has been related to wide-ranging health effects in children, leading to lifelong concerns. Proportionally, dietary i-As exposure dominates in regions with low arsenic drinking water. This study aims to investigate the relation between rice and seafood consumption and urinary arsenic species during childhood and to assess the proportion of urinary i-As metabolites. Urinary arsenic species concentration in 400 4-year-old children living in four geographical areas of Spain, in addition to repeated measures from 100 children at 7 years of age are included in this study. Rice and seafood products intake was collected from children's parents using a validated food frequency questionnaire (FFQ). At 4 years of age, children's urine i-As and monomethylarsonic acid (MMA) concentrations increased with rice product consumption (p-value = 0.010 and 0.018, respectively), and urinary arsenobetaine (AsB) with seafood consumption (p = 0.002). Four-year-old children had a higher consumption of both rice and seafood per body weight and a higher urinary %MMA (p-value = 0.001) and lower % dimethylarsinic acid (DMA) (p-value = 0.017). This study suggests increased dietary i-As exposure related to rice product consumption among children living in Spain, and the younger ones may be especially vulnerable to the health impacts of this exposure also considering that they might have a lower i-As methylation capacity than older children. In contrast, seafood consumption did not appear to influence the presence of potentially toxic arsenic species in this population of children.

Heterogeneity of vitamin D receptor gene association with celiac disease and type 1 diabetes mellitus

OBJECTIVE

Vitamin D has been shown to exert multiple immunomodulatory effects and is known to suppress T-cell activation by binding to the vitamin D receptor (VDR). To determine whether VDR gene polymorphisms are related to the susceptibility to celiac disease, we investigated its implication as a candidate gene in the Basque population. Because celiac disease and type 1 diabetes share common susceptibility loci, we also analyzed families with type 1 diabetes mellitus.

METHODS

A total of 37 families with celiac disease and 64 type 1 diabetic families of Basque origin with at least one affected offspring were genotyped for four VDR restriction-site polymorphisms (Fok I, Bsm I, Apa I and Taq I). The AFBAC approach was used to test for association.

RESULTS

Comparison of VDR genotypes of the patients with those of 88 healthy individuals identified "ff" as a risk genotype for celiac disease [p = 0.01; OR = 3.45 (1.12-10.79)]. On the other hand, a significantly higher frequency of haplotype "fBAt" was observed in the type 1 diabetic group [p(c) = 0.02; OR = 4.4 (1.5-15.3)].

CONCLUSION

Our findings suggest that polymorphisms within the vitamin D receptor gene are markers of susceptibility to or protection from autoimmune diseases, although, at least in the Basque population, association of VDR variants with celiac disease and type 1 diabetes seems to be heterogeneous.

The functional R620W variant of the PTPN22 gene is associated with celiac disease

The functional (R620W) variant of human PTPN22 (protein tyrosine phosphatase non-receptor 22) gene has been implicated in the risk to several autoimmune disorders, including type 1 diabetes, Graves' disease, rheumatoid arthritis and systemic lupus erythematosus. In an association study of this single nucleotide polymorphism with celiac disease (CD), comparison of 262 young diagnosis patients and 214 adult controls from Spain showed a higher frequency of the minor allele in the CD group (9.7% vs 5.6% in controls; P = 0.018), suggestive of an increased genetic risk to the disease (odds ratio = 1.82; 95% confidence interval 1.1-3.0). These results support the role of PTPN22 as a general autoimmunity locus involved in tolerance induction in the thymus.

Toll-like receptor 4 (TLR4) gene polymorphisms in celiac disease

Toll-like receptors (TLRs) participate in the first line of immune defense through antigen pattern recognition, and ligands include exogenous and host-derived molecules. Coding variants in TLR4 have been associated with autoimmune diseases like ulcerative colitis, Crohn's disease, and rheumatoid arthritis. Our aim was to determine whether these polymorphisms are associated with celiac disease (CD). Two coding single nucleotide polymorphisms of TLR4 (Asp299Gly and Thr399Ile) were genotyped in 95 family trios with CD as well as in 186 patients and 186 unrelated controls. There were no differences in allele, genotype or haplotype distribution, or transmission between patient and control groups. Our results do not support association of these TLR4 variants with CD.

The majority of cases of neonatal diabetes in Spain can be explained by known genetic abnormalities

BACKGROUND

Neonatal diabetes is a rare disease characterized by hyperglycaemia within the first 3 months of life and requiring insulin treatment; it can either be transient (TNDM) or permanent (PNDM). Alterations at band 6q24 and heterozygous activating mutations in KCNJ11, the gene encoding the pore-forming subunit of the KATP channel, can cause neonatal diabetes. Aims We screened the 6q24 region, KCNJ11, GCK, FOXP3 and IPF1 genes for mutations in families with PNDM or TNDM to establish a phenotype-genotype correlation.

METHODS

Twenty-two patients with neonatal diabetes were recruited. Inclusion criteria were insulin-treated diabetes diagnosed within the first 3 months and insulin treatment for at least 15 days. Clinical data were recorded in a questionnaire.

RESULTS

We identified 17 genetic alterations in our patients: six alterations at the 6q24 band associated with TNDM and nine mutations in KCNJ11, five of which were novel. The analysis for a phenotype-genotype correlation showed that patients with 6q24 alterations had a lower birth weight and were diagnosed earlier than patients with KCNJ11 mutations. At follow-up of the TNDM patients with genetic alterations, 43% developed diabetes or impaired glucose tolerance in later life (one with 6q24 duplication and two with N48D and E227K mutations at KCNJ11 gene). Furthermore, half the first-degree relatives who carried a genetic alteration but who had not suffered from neonatal diabetes were diagnosed with diabetes or impaired glucose tolerance before the age of 30 years.

CONCLUSIONS

KCNJ11 mutations are common in both TNDM and PNDM and are associated with a higher birth weight compared with patients with 6q24 abnormalities. Patients with TNDM should be screened for abnormalities in glucose metabolism in adult life.

Association of KIR2DL5B gene with celiac disease supports the susceptibility locus on 19q13.4

Genome-wide scans have detected linkage to celiac disease (CD) in several genomic locations, including 19q13.4. Killer immunoglobulin-like receptor (KIR) genes map to the region and encode receptors of natural killer (NK) cells and certain T cells that modulate cytolitic activity through interactions with HLA class I ligands, participating in the innate immune response. We performed KIR genotyping in a group of 70 CD patients of Basque origin and compared gene content, genotype and haplotype frequencies to ethnically matched blood-donors. The frequency of gene combination KIR2DL5B(+)/KIR2DL5A(-) was significantly higher in the disease group, and this result was confirmed in a second group of 343 CD patients and 160 controls of Spanish origin, suggesting an implication of this 'unexpressed' gene with increased susceptibility to CD (combined OR of 3.63 (95% CI: 1.76-7.51; P=0.0004)), possibly due to the lack of an efficient inhibitory signal. Our results support the role of the KIR gene cluster in celiac disease and replicate the CD-susceptibility locus at 19q13.4.

Conserved extended haplotypes discriminate HLA-DR3-homozygous Basque patients with type 1 diabetes mellitus and celiac disease

The major susceptibility locus for type 1 diabetes mellitus (T1D) maps to the human lymphocyte antigen (HLA) class II region in the major histocompatibility complex on chromosome 6p21. In southern European populations, like the Basques, the greatest risk to T1D is associated with DR3 homo- and heterozygosity and is comparable to that of DR3/DR4, the highest risk genotype in northern European populations. Celiac disease (CD) is another DR3-associated autoimmune disorder showing certain overlap with T1D that has been explained by the involvement of common genetic determinants, a situation more frequent in DR3-rich populations, like the Basques. As both T1D- and CD-associated HLA alleles are part of conserved extended haplotypes (CEH), we compared DR3-homozygous T1D and CD patients to determine whether CEHs were equally distributed between both disorders or there was a differential contribution of different haplotypes. We observed a very pronounced distribution bias (P<10(-5)) of the two major DR3 CEHs, with DR3-B18 predominating in T1D and DR3-B8 in CD. Additionally, high-density single nucleotide polymorphism (SNP) analysis of the complete CEH [A*30-B*18-MICA*4-F1C30-DRB1*0301-DQB1*0201-DPB1*0202] revealed extraordinary conservation throughout the 4.9 Mbp analyzed supporting the existence of additional diabetogenic variants (other than HLA-DRB1*0301-DQB1*0201), conserved within the DR3-B18 CEH (but not in other DR3 haplotypes) that could explain its enhanced diabetogenicity.

Molecular analysis of Frasier syndrome: mutation in the WT1 gene in a girl with gonadal dysgenesis and nephronophthisis

The Wilms' tumor gene (WT1) encodes a protein that is believed to exert transcriptional and tumor-suppressor activities. Mutations in this gene have occasionally been associated with Wilms' tumor (<15% patients) and, more consistently, with three syndromes characterized by urogenital abnormalities (WAGR, Denys-Drash and Frasier syndromes). We report 17 years follow-up of a 29 year-old phenotypic female with 46,XY karyotype, gonadal dysgenesis and nephronophthisis in order to identify possible germline alterations of the WT1 gene. Frasier syndrome was suspected and confirmed by genetic analysis. Sequence analysis permitted the identification of an A40-->G mutation in position +5 in the donor splice site of intron 9. During surgery for streak gonads extirpation, a microscopic gonadoblastoma was found, a typical complication of Frasier syndrome.

HLA-DRB1 and MHC class 1 chain-related A haplotypes in Basque families with celiac disease

The contribution of HLA genes to the genetic risk for celiac disease (CD) has been known for a long time. Recent publications have pointed to the possibility that a second, independent susceptibility locus could be located in the same genomic region, and a triplet repeat polymorphism in exon 5 of the gene MHC class I chain-related protein A (MICA; located between TNFA and HLA-B) has been associated with several autoimmune disorders, including type 1 diabetes mellitus (DM1) and Addison's disease. On the other hand, a single amino acid change in exon 3 of MICA (M129V) has been shown to strongly reduce MICA binding to NKG2D, an activating natural killer receptor expressed also on T cells, and this could have significant effects on autoimmune reactions. In this study, we have analyzed the contribution of these polymorphisms to CD in 37 Basque families, and have constructed MICA-HLA-DRB1 haplotypes to determine whether MICA has an effect independent from the HLA class II conferred risk. In our population, HLA-DRB1*0301 was associated with an increased risk for CD, while HLA-DRB1*1501 conferred protection from the disease (OR: 7.38 and 0.06, respectively). On the other hand, MICA allele A4 was positively associated with the disease (OR: 4.69) whereas allele A9 showed a trend towards protection (OR: 0.18), although significance did not hold after correction. No association of the exon 3 biallelic polymorphism was observed. A positive allelic association was found for haplotypes A5.1-DRB1*0301 (associated with risk for disease), A4-DRB1*0301 and A6-DRB1*07. In view of our results, both HLA-DRB1 and MICA are associated with CD, but stratification analysis did not show any independent contribution of the MICA polymorphisms analyzed to CD risk. Besides, MICA allele A4 (also A5.1 was associated with risk for CD and other diseases) is in strong linkage disequilibrium with HLA-DRB1*0301. Finally, the major histocompatibility complex region's conferred susceptibility to CD, at least in Basque, is very similar to that observed for DM1, with shared risk and protective haplotypes.

Familial hypercalcemia and hypercalciuria: no mutations in the Ca2+-sensing receptor gene

A 6-year-old boy presented with persistent hypercalcemia, hypercalciuria and nephrocalcinosis from early infancy. His 40-year-old father also had hypercalcemia and hypercalciuria. In both individuals serum values of intact parathyroid hormone (PTH) were repeatedly normal. Although these findings suggest a functional abnormality of the calcium-sensing receptor (CaR), no mutations in coding regions of the CaR gene could be demonstrated.

Influence of sex and age at onset on autoantibodies against insulin, GAD65 and IA2 in recent onset type 1 diabetic patients

METHODS

Autoantibodies against insulin (IAA), glutamic acid decarboxylase (GADA) and tyrosine phosphatase IA2 (IA2A) were measured in sera from 448 recent onset patients with type 1 diabetes mellitus (DM) subdivided according to sex (194 female and 254 male) and age at onset (134 patients diagnosed before 10 years, 187 between 10 and 20 years, 66 between 20 and 30 years and 61 over 30 years.

RESULTS

Autoantibodies were more frequent in female DM patients (93.8 vs. 86.6%, p = 0.013) due to an increased prevalence of both GADA (86.1 vs. 70.1%) and IA2A (59.3 vs. 49.2%), with GADA levels also significantly higher in women (0.24 vs. 0.18 U, p = 0.0003). When age groups were compared, there was a reduction in prevalence in patients over 20 years for both IAA (70% for patients diagnosed under 20 and 36% for older patients) and IA2A (65 and 25%, respectively). These differences also affected IAA levels, with the highest antibody titres in the youngest group (1,214.1 nU/ml in children under 10 compared to 546.9, 345.6 and 341.1 nU/ml in the subsequent groups; p < 10(-4)). GADA prevalence did not differ significantly between age groups but, nevertheless, autoantibody levels were highest among the oldest type 1 DM patients (0.327 U compared to 0.216, 0.197 and 0.176 U in the decreasing age groups; p < 10(-4)).

CONCLUSION

There are sex- and age-related differences affecting the presence and/or titres of beta cell autoantibodies. We speculate that these differences could reflect the severity and specificity of the autoimmune attack against the endocrine pancreas and might influence the rate of progression to type 1 DM or the risk of developing other autoimmune diseases.

Branchio-oto-renal syndrome: identification of a novel mutation in the EYA1 gene

Branchio-oto-renal (BOR) syndrome is an autosomal dominant disorder characterized by the association of branchial cysts or fistulae, external ear malformation and/or preauricular pits, hearing loss, and renal anomalies. Mutations in the EYA1 gene, a human homologue of the Drosophila 'eyes absent' gene, have been identified as cause of the syndrome. We report here two families with BOR syndrome. In one family, with the complete phenotype, a novel splice site mutation in exon 15 (1599 +1 G to A) is described. No mutations in the EYA1 gene were found in a second family presenting with ear pits, deafness, and renal anomalies, but lacking branchial fistulae. These and other findings from the literature suggest the existence of genetic heterogeneity of the BOR, BO, and other related phenotypes, with two or more genes involved.

Analysis of chromosome 6q in Basque families with type 1 diabetes. GEPV-N. Basque-Navarre Endocrinology and Paediatric Group

Over the last few years several studies of linkage between non-HLA loci and type 1 diabetes mellitus have mapped several putative susceptibility genes on chromosome 6q; in fact, positive evidence of linkage and/or association of IDDM5 (6q25), IDDM8 (6q27) and IDDM15 (6q21) with type 1 diabetes has been reported. We have studied these loci in diabetic families of Basque origin, a genetically homogeneous population, to avoid artifactual association results due to admixture within the sample analysed. Statistical analyses of linkage were performed using a transmission disequilibrium test (TDT). We could not confirm linkage for IDDM5, IDDM8 and IDDM15 in our population, possibly due to population-specific differences in genetic susceptibility and/or environmental triggering factors to type 1 diabetes.

Molecular analysis in familial neurohypophyseal diabetes insipidus: early diagnosis of an asymptomatic carrier

Familial neurohypophyseal diabetes insipidus (FNDI) is an inherited deficiency of the hormone arginine vasopressin (AVP) and is transmitted as an autosomal dominant trait. In the present study we have analyzed the AVP-neurophysin II (AVP-NPII) gene in a Spanish kindred. Studies were performed on seven members (four clinically affected) of the family. Patients were diagnosed at the Hospital Universitario Gregorio Marañón (Madrid, Spain). The entire coding region of the AVP-NPII gene of all family members was amplified by PCR and sequenced. All affected individuals presented a missense mutation (G1757-->A) that replaces glycine at position 23 with arginine within the NPII domain. The substitution was confirmed by restriction endonuclease analysis and was present in heterozygosis. Additionally, one of the asymptomatic relatives (a girl 8 months old at the time of study) was identified as carrier of the same mutation and developed the disease 3 months later. The alteration found in the second exon of the gene in this family seems to be responsible for the disease, as all individuals harboring the mutation had been previously diagnosed or have eventually developed FNDI. Identification of the molecular defect underlying FNDI in affected families is a powerful tool for early asymptomatic diagnosis in infants.

A novel missense (R80W) mutation in 17-beta-hydroxysteroid dehydrogenase type 3 gene associated with male pseudohermaphroditism

OBJECTIVE

Deficit of the testosterone converting enzyme 17-beta-hydroxysteroid dehydrogenase (17beta-HSD) has been shown to be responsible for male pseudohermaphroditism (MPH). We analysed the gene encoding 17beta-HSD type 3 (17beta-HSD3) in a patient with MPH.

METHODS

We studied a 46, XY new-born diagnosed as having MPH. The child also had other congenital disorders, including a giant omphalocele and Fallot's tetralogy, and died of post-surgical complications at age 4.5 months. Basal hormonal levels, and after human chorionic gonadotrophin stimulation, suggested a deficiency in 17beta-HSD as the biochemical defect underlying this MPH. PCR amplification and subsequent sequencing of all coding exons of the 17beta-HSD3 gene were performed on genomic DNA from the patient and both parents. Messenger RNA was extracted from the patient's testis and 17beta-HSD3 cDNA was synthesized, PCR amplified and sequenced.

RESULTS

Sequencing revealed the presence of a homozygous missense mutation (R80W) in exon 3 of the 17beta-HSD3 gene, which was also present in single doses in both parents, in accordance with the recessive inheritance of the defect. No other mutation was found, and cDNA sequencing confirmed correct synthesis and processing of 17beta-HSD3 mRNA.

CONCLUSIONS

Confirming the abnormal delta4-androstenedione/testosterone ratios that suggested 17beta-HSD deficiency, a homozygous missense mutation in the gene coding for this enzyme was identified in the patient with MPH. This study adds further genetic evidence to the role of 17beta-HSD3 in male sexual development. There is no evidence supporting the association of this mutation in 17beta-HSD3 with the congenital malformations other than MPH present in the child.

Anomalous behaviour of the 5' insulin gene polymorphism allele 814: lack of association with Type I diabetes in Basques. GEPV-N Group. Basque-Navarre Endocrinology and Paediatrics

A susceptibility locus (IDDM2) for Type I (insulin-dependent) diabetes mellitus has been identified as allelic variation at a variable number of tandem repeats polymorphic region upstream of the human insulin gene. In Caucasian populations, individuals homozygous for the short length alleles (26 to 63 repeats: class I) have a two- to fivefold increased risk of developing the disease, while the long alleles (more than 140 repeats: class III) are dominantly protective. Recent evidence has shown that class I alleles are not equally predisposing, and in particular, the 42-repeat allele (allele 814) can be protective when paternally inherited. We have assessed the contribution of IDDM2 to disease in a group of Basque families with Type I diabetes. As in other Caucasoid populations, we found that class I alleles, as a whole, are associated with an increased risk of developing the disease. Using a polymerase chain reaction-based assay to more accurately resolve the different sizes of individual class I alleles, we identified 14 different variants and observed that allele 814 has an anomalous behaviour in Basques, being the only class I allele that does not have an increased frequency in the diabetic alleles group. These findings provide additional support for the recently published allele-specific effects of IDDM2 in Type I diabetes pathogenesis.

Association of insulin-dependent diabetes mellitus and celiac disease: a study based on serologic markers

BACKGROUND

The association of celiac disease and insulin-dependent diabetes mellitus has been known for some time. In an attempt to clarify this association, the prevalence of celiac disease among diabetic children was determined, and the risk of insulin-dependent diabetes mellitus was defined in pediatric patients with celiac disease.

METHODS

Ninety-three children with diabetes were analyzed for the presence of celiac disease-related markers (antigliadin and antiendomysial antibodies) and characteristic alterations in the intestinal mucosa. In another group, 93 children with celiac disease were screened for pancreatic autoantibodies and pancreatic beta-cell function.

RESULTS

Among children with insulin-dependent diabetes mellitus, a 6.45% prevalence of celiac disease was observed, a value significantly higher than that found among healthy controls. In contrast, only three celiac disease patients showed potential autoimmunity toward the pancreatic beta cell, a proportion not significantly different from that in the general population. Additionally, no alteration of glucose metabolism was observed in the antibody-positive patients.

CONCLUSION

The increased risk of celiac disease among patients with diabetes requires a long follow-up to determine the presence of celiac disease markers among patients with diabetes, to avoid potential malignant disease derived from untreated celiac disease. In contrast, there is no evidence to support an increased risk of insulin-dependent diabetes mellitus among children with celiac disease. In accordance with the accepted influence of diet in the development of autoimmune diabetes, a hypothetical mechanism of protection against insulin-dependent diabetes mellitus that is mediated by environmental factors related to restricted diet is suggested in this population.

Identification of a novel nonsense mutation and a missense substitution in the vasopressin-neurophysin II gene in two Spanish kindreds with familial neurohypophyseal diabetes insipidus

Familial neurohypophyseal diabetes insipidus (FNDI) is an autosomal dominant disease caused by deficiency in the antidiuretic hormone arginine vasopressin (AVP) encoded by the AVP-neurophysin II (AVP-NPII) gene on chromosome 20p13. In this study, we analyzed two families with FNDI using direct automated fluorescent, solid phase, single-stranded DNA sequencing of PCR-amplified AVP-NPII DNA. In one of the families, affected individuals presented a novel nonsense mutation in exon 3 of the gene, consisting in a G to T transition at nucleotide 2101, which produces a stop signal in codon 82 (Glu) of NPII. The premature termination eliminates part of the C-terminal domain of NPII, including a cysteine residue in position 85, which could be involved in the correct folding of the prohormone. In the second family, a G279A substitution at position -1 of the signal peptide was observed in all affected individuals. This missense mutation, which replaces Ala with Thr, is frequent among FNDI patients and is thought to reduce the efficiency of cleavage by signal peptidases.

Anti-insulin activity in normal newborn cord-blood serum: absence of IgG-mediated insulin binding

Insulin autoantibodies (IAAs) are present in approximately 60% of type I diabetes patients at onset and are used as predictors for the disease. Although the prevalence of IAAs in the general population has been reported to be <1%, preliminary data have pointed out a higher proportion of IAA positivity in newborn cord-blood serum, and some authors have suggested that they are immunoglobulin G antibodies, resulting from a hypothetical gestational insulitis. To characterize this insulin-binding activity, we analyzed cord-blood sera from 100 healthy newborns, as well as serum from 21 of their mothers at delivery, 179 new-onset type I diabetic patients, and 200 healthy control subjects. IAAs were present in 0.5% of the control subjects and 54% of new-onset type I diabetic patients. On the other hand, 96% of the newborn cord-blood sera showed anti-insulin activity, while it was detected in only 14% of their mothers. No significant differences were observed between cord sera and the general population for islet-cell or anti-GAD autoantibodies. Anti-insulin activity in cord serum was not bound by protein A or protein G, in contrast with type I diabetes-related IAA activity. We conclude that this insulin-binding activity, present in most newborn cord sera and specific to the child, is not IgG mediated. These data, together with the absence of other pancreatic autoimmunity markers in this population, suggest that it is an isolated phenomenon not related to type I diabetes or other pancreatic autoimmune processes and is due to the presence of a cross-reacting molecule in cord blood that has yet to be identified.

A novel postzygotic nonsense mutation in SRY in familial XY gonadal dysgenesis

The Y chromosome gene SRY plays an important role in normal male sexual development and is thought to be the testis-determining factor. We describe a familial nonsense mutation in SRY, shared by two XY sisters with complete gonadal dysgenesis and, in a mosaic manner, by their father. This mutation, consisting of a C to T transition in position 1 of codon 97 of SRY, results in a truncated peptide with an incomplete DNA-binding domain. The mutation is also present in the father of the two cases, but a portion of wild-type SRY also remains. Our data suggest that the father suffered a postzygotic mutation early in development, but that he retained a remnant of functional SRY protein that accounts for his normal development.

[Virulence factors and 0 serogroups of Escherichia coli as a cause of community-acquired urinary infections]

BACKGROUND

The aim of this study was to determine the virulence factors and 0 serogroups of E. coli strains that cause community acquired urinary tract infections (UTI).

METHODS

We examined 103 E. coli strains isolated from the urine of patients with UTI. The following virulence factors were investigated using phenotypic techniques: the alpha-haemolysin (Hly), the cytotoxic necrotizing factor type 1 (CNF-1) and the mannose-resistant haemagglutination (MRHA) types III, IVa and IVb expressed by P fimbriated E. coli. Serotyping of 0 antigen was carried out by means of a microtechnique using 163 antisera.

RESULTS

Fifty-five (53%) of the 103 E. coli strains examined showed some of the virulence factors investigated in this study; 41% of the strains were Hly+, 28% were CNF-1+ and 48% expressed MRHA types III, IVa or IVb. The uropathogenic strains characterized belonged to 27 different 0 serogroups. However, 68% were from one of 10 serogroups (01, 02, 04, 06, 09, 018, 027, 073, 075 and 077) and 36% were from one of only 3 serogroups (02, 04 and 06). Furthermore, the virulence factors were concentrated in strains belonging to the 3 serogroups most frequently detected. Thus, 36 (97%) of the 37 strains of these 3 serogroups showed virulence factors, versus only 19 (29%) of 66 belonging to other serogroups (p < 0.001).

CONCLUSIONS

Our results support the special pathogenicity theory and suggest that many cases of community acquired UTI may be caused by a limited number of uropathogenic E. coli strains that produce toxins (Hly+ and/or CNF-1+) and possess P fimbriae or P-related adhesins (with MRHA types III, IVa or IVb), and that usually belong to 02, 04 and 06 serogroups.

[Detection of virulence factors using DNA probes in uropathogenic strains of Escherichia coli]

BACKGROUND

There are several bacterial determinants that contribute to the onset of urinary tract infection by E. coli. The present study focuses on some of the virulence factors considered to be most important, as P fimbriae, the siderophore aerobactin and bacterial capsule, which were studied among 123 uropathogenic E. coli strains isolated from outpatients from the Basque Community.

METHODS

Virulence factors were detected using Molecular Biology techniques, namely DNA hybridization to specific probes prepared in our laboratory.

RESULTS

When probe pap2, specific for fimbrial adherence was used, 36.5% of the strains showed positive hybridization, and 66 and 73% of the strains hybridized to probes for aerobactin and common capsule region, respectively.

CONCLUSIONS

We believe that this technology provides a very useful tool for rapid and easy screening of strains harbouring different virulence factors. Nevertheless, the fact that these methods detect genetic determinants that are not always being expressed must be borne in mind.