Fine mapping of the celiac disease-associated LPP locus reveals a potential functional variant

Using the Immunochip for genotyping, we identified 39 non-human leukocyte antigen (non-HLA) loci associated to celiac disease (CeD), an immune-mediated disease with a worldwide frequency of ∼1%. The most significant non-HLA signal mapped to the intronic region of 70 kb in the LPP gene. Our aim was to fine map and identify possible functional variants in the LPP locus. We performed a meta-analysis in a cohort of 25 169 individuals from six different populations previously genotyped using Immunochip. Imputation using data from the Genome of the Netherlands and 1000 Genomes projects, followed by meta-analysis, confirmed the strong association signal on the LPP locus (rs2030519, P = 1.79 × 10(-49)), without any novel associations. The conditional analysis on this top SNP-indicated association to a single common haplotype. By performing haplotype analyses in each population separately, as well as in a combined group of the four populations that reach the significant threshold after correction (P < 0.008), we narrowed down the CeD-associated region from 70 to 2.8 kb (P = 1.35 × 10(-44)). By intersecting regulatory data from the ENCODE project, we found a functional SNP, rs4686484 (P = 3.12 × 10(-49)), that maps to several B-cell enhancer elements and a highly conserved region. This SNP was also predicted to change the binding motif of the transcription factors IRF4, IRF11, Nkx2.7 and Nkx2.9, suggesting its role in transcriptional regulation. We later found significantly low levels of LPP mRNA in CeD biopsies compared with controls, thus our results suggest that rs4686484 is the functional variant in this locus, while LPP expression is decreased in CeD.

Improving coeliac disease risk prediction by testing non-HLA variants additional to HLA variants

BACKGROUND

The majority of coeliac disease (CD) patients are not being properly diagnosed and therefore remain untreated, leading to a greater risk of developing CD-associated complications. The major genetic risk heterodimer, HLA-DQ2 and DQ8, is already used clinically to help exclude disease. However, approximately 40% of the population carry these alleles and the majority never develop CD.

OBJECTIVE

We explored whether CD risk prediction can be improved by adding non-HLA-susceptible variants to common HLA testing.

DESIGN

We developed an average weighted genetic risk score with 10, 26 and 57 single nucleotide polymorphisms (SNP) in 2675 cases and 2815 controls and assessed the improvement in risk prediction provided by the non-HLA SNP. Moreover, we assessed the transferability of the genetic risk model with 26 non-HLA variants to a nested case-control population (n=1709) and a prospective cohort (n=1245) and then tested how well this model predicted CD outcome for 985 independent individuals.

RESULTS

Adding 57 non-HLA variants to HLA testing showed a statistically significant improvement compared to scores from models based on HLA only, HLA plus 10 SNP and HLA plus 26 SNP. With 57 non-HLA variants, the area under the receiver operator characteristic curve reached 0.854 compared to 0.823 for HLA only, and 11.1% of individuals were reclassified to a more accurate risk group. We show that the risk model with HLA plus 26 SNP is useful in independent populations.

CONCLUSIONS

Predicting risk with 57 additional non-HLA variants improved the identification of potential CD patients. This demonstrates a possible role for combined HLA and non-HLA genetic testing in diagnostic work for CD.

Dense genotyping identifies and localizes multiple common and rare variant association signals in celiac disease

Using variants from the 1000 Genomes Project pilot European CEU dataset and data from additional resequencing studies, we densely genotyped 183 non-HLA risk loci previously associated with immune-mediated diseases in 12,041 individuals with celiac disease (cases) and 12,228 controls. We identified 13 new celiac disease risk loci reaching genome-wide significance, bringing the number of known loci (including the HLA locus) to 40. We found multiple independent association signals at over one-third of these loci, a finding that is attributable to a combination of common, low-frequency and rare genetic variants. Compared to previously available data such as those from HapMap3, our dense genotyping in a large sample collection provided a higher resolution of the pattern of linkage disequilibrium and suggested localization of many signals to finer scale regions. In particular, 29 of the 54 fine-mapped signals seemed to be localized to single genes and, in some instances, to gene regulatory elements. Altogether, we define the complex genetic architecture of the risk regions of and refine the risk signals for celiac disease, providing the next step toward uncovering the causal mechanisms of the disease.

Meta-analysis of genome-wide association studies in celiac disease and rheumatoid arthritis identifies fourteen non-HLA shared loci

Epidemiology and candidate gene studies indicate a shared genetic basis for celiac disease (CD) and rheumatoid arthritis (RA), but the extent of this sharing has not been systematically explored. Previous studies demonstrate that 6 of the established non-HLA CD and RA risk loci (out of 26 loci for each disease) are shared between both diseases. We hypothesized that there are additional shared risk alleles and that combining genome-wide association study (GWAS) data from each disease would increase power to identify these shared risk alleles. We performed a meta-analysis of two published GWAS on CD (4,533 cases and 10,750 controls) and RA (5,539 cases and 17,231 controls). After genotyping the top associated SNPs in 2,169 CD cases and 2,255 controls, and 2,845 RA cases and 4,944 controls, 8 additional SNPs demonstrated P<5×10⁻⁸ in a combined analysis of all 50,266 samples, including four SNPs that have not been previously confirmed in either disease: rs10892279 near the DDX6 gene (P_combined = 1.2×10⁻¹²), rs864537 near CD247 (P_combined = 2.2×10⁻¹¹), rs2298428 near UBE2L3 (P_combined = 2.5×10⁻¹⁰), and rs11203203 near UBASH3A (P_combined = 1.1×10⁻⁸). We also confirmed that 4 gene loci previously established in either CD or RA are associated with the other autoimmune disease at combined P<5×10⁻⁸ (SH2B3, 8q24, STAT4, and TRAF1-C5). From the 14 shared gene loci, 7 SNPs showed a genome-wide significant effect on expression of one or more transcripts in the linkage disequilibrium (LD) block around the SNP. These associations implicate antigen presentation and T-cell activation as a shared mechanism of disease pathogenesis and underscore the utility of cross-disease meta-analysis for identification of genetic risk factors with pleiotropic effects between two clinically distinct diseases.

Celiac disease (CD) and rheumatoid arthritis (RA) are two autoimmune diseases characterized by distinct clinical features but increased co-occurrence in families and individuals. Genome-wide association studies (GWAS) performed in CD and RA have identified the HLA region and 26 non-HLA genetic risk loci in each disease. Of the 26 CD and 26 RA risk loci, previous studies have shown that six are shared between the two diseases. In this study we aimed to identify additional shared risk alleles and, in doing so, gain more insight into shared disease pathogenesis. We first empirically investigated the distribution of putative risk alleles from GWAS across both diseases (after removing known risk loci for both diseases). We found that CD risk alleles are non-randomly distributed in the RA GWAS (and vice versa), indicating that CD risk alleles have an increased prior probability of being associated with RA (and vice versa). Next, we performed a GWAS meta-analysis to search for shared risk alleles by combing the RA and CD GWAS, performing both directional and opposite allelic effect analyses, followed by replication testing in independent case-control datasets in both diseases. In addition to the already established six non-HLA shared risk loci, we observed statistically robust associations at eight SNPs, thereby increasing the number of shared non-HLA risk loci to fourteen. Finally, we used gene expression studies and pathway analysis tools to identify the plausible candidate genes in the fourteen associated loci. We observed remarkable overrepresentation of T-cell signaling molecules among the shared genes.

Human RSPO1/R-spondin1 is expressed during early ovary development and augments β-catenin signaling

Human testis development starts from around 42 days post conception with a transient wave of SRY expression followed by up-regulation of testis specific genes and a distinct set of morphological, paracrine and endocrine events. Although anatomical changes in the ovary are less marked, a distinct sub-set of ovary specific genes are also expressed during this time. The furin-domain containing peptide R-spondin1 (RSPO1) has recently emerged as an important regulator of ovary development through up-regulation of the WNT/β-catenin pathway to oppose testis formation. Here, we show that RSPO1 is upregulated in the ovary but not in the testis during critical early stages of gonad development in humans (between 6-9 weeks post conception), whereas the expression of the related genes WNT4 and CTNNB1 (encoding β catenin) is not significantly different between these tissues. Furthermore, reduced R-spondin1 function in the ovotestis of an individual (46,XX) with a RSPO1 mutation leads to reduced β-catenin protein and WNT4 mRNA levels, consistent with down regulation of ovarian pathways. Transfection of wild-type RSPO1 cDNA resulted in weak dose-dependent activation of a β-catenin responsive TOPFLASH reporter (1.8 fold maximum), whereas co-transfection of CTNNB1 (encoding β-catenin) with RSPO1 resulted in dose-dependent synergistic augmentation of this reporter (approximately 10 fold). Furthermore, R-spondin1 showed strong nuclear localization in several different cell lines. Taken together, these data show that R-spondin1 is upregulated during critical stages of early human ovary development and may function as a tissue-specific amplifier of β-catenin signaling to oppose testis determination.

HLA-DQ and risk gradient for celiac disease

Celiac disease (CD) is a rare example of multifactorial disorder in which a genetic test is of great clinical relevance, as the disease rarely develops in the absence of specific HLA alleles. We typed DR-DQ genes in 437 Italian children with celiac disease, 834 first-degree relatives, and 551 controls. Of patients, 91% carried DQ2 and/or DQ8 heterodimers, 6% only had beta2 chain, 2% was alpha5 positive, and four were DQ2/DQ8/beta2/alpha5 negative. Only the presence of alpha5 resulted negatively associated to disease (p = 2 x 10(-4)), whereas we confirmed the effect of the beta half of DQ2 dimer on CD predisposition (p = 4 x 10(-12)). Considering 1:100 disease prevalence, we obtained a risk gradient ranging from 1:7 for DQ2 and DQ8 individuals down to 1:2518 for subjects lacking all predisposing factors. The DQB1*02 and DQB1*0302 concurrence (p = 9 x 10(-4)), besides the DQB1*02/*02 homozygosity, had an additional role in disease genetic determination. The CD prevalence rose to 17.6% in sisters, 10.8% in brothers, and 3.4% in parents. In the three groups, the subjects carrying high-risk HLA molecules were 57%, 71%, and 58%; among them, 29%, 15%, and 6% respectively had CD. Those siblings and parents with no susceptible factors were not affected. These findings indicate the impact of the HLA test for CD in clinical practice.

Identification of a novel duplication in the APC gene using multiple ligation probe amplification in a patient with familial adenomatous polyposis

Germline mutations in the adenomatous polyposis coli (APC) gene cause familial adenomatous polyposis (FAP), an autosomal dominant disease characterized by hundreds to thousands of adenomatous polyps in the colon and rectum, with progression to colorectal cancer. The majority of APC mutations are nucleotide substitutions and frameshift mutations that result in truncated proteins. Recently, large genomic alterations of the APC gene have been reported in FAP. DNA from 15 FAP patients, in whom no APC germline mutations were detected with denaturing high performance liquid chromatography, was analyzed with multiplex ligation-dependent probe amplification (MLPA) to evaluate gross genomic alterations in the APC gene. In one case, MLPA identified a novel duplication of exons 2-6 in one copy of the APC gene. Reverse transcriptase-polymerase chain reaction revealed that the mutant allele contained an in-frame multiexon duplication including 18 nucleotides located in exon 2, upstream of the ATG initiation codon. The presence of a premature stop codon in the duplicated sequence leads to the synthesis of a truncated APC polypeptide. These findings highlight the utility of evaluating infrequent APC mutation events in FAP patients using MLPA.

A rapid and sensitive method to detect specific human lymphocyte antigen (HLA) class II alleles associated with celiac disease

BACKGROUND

Celiac disease (CD) is a complex disorder triggered by gluten affecting genetically predisposed individuals. More than 90% of patients carry human lymphocyte antigen (HLA)-DQ2 (DQA1*05, DQB1*02) and/or HLA-DQ8 (DQA1*03, DQB1*0302). We propose the use of the DQ-CD Typing kit that allows identification of the HLA class II alleles (DQA1*0201,*03,*05, DQB1*02,*0302, DRB1*03,*04,*07) selected to be informative in the CD risk evaluation and of a second kit, namely DQ-CD Zygosis, for DQB1*02 homozygosity determination.

METHODS

The study was performed on a cohort of 100 individuals previously HLA typed with commercial kits. Fresh blood or previously extracted DNA was amplified in a unique PCR program using allele-specific primers and visualized on agarose gel.

RESULTS

DNA amplification yielded strong and clear products without non specific signals or ghost bands. All the samples showed the expected alleles in accordance with the previous HLA typing.

CONCLUSIONS

The DQ-CD Typing and Zygosis kits are fast, simple, economical and accurate tools that can be used to determinate the HLA-DQ2/DQ8 status in laboratory practice addressed for the diagnosis of CD. Molecular HLA testing is considered a valid support in the confirmation/exclusion of CD, especially in high-risk groups, such as CD relatives, or when serological and histological data are ambiguous.

Syndromic true hermaphroditism due to an R-spondin1 (RSPO1) homozygous mutation

XX true hermaphroditism, also know as ovotesticular disorder of sexual development (DSD), is a disorder of gonadal development characterized by the presence of both ovarian and testicular tissue in a 46,XX individual. The genetic basis for XX true hermaphroditism and sex reversal syndromes unrelated to SRY translocation is still mostly unclear. We report mutational analysis of the RSPO1 gene in a 46,XX woman with true hermaphroditism, palmoplantar keratoderma, congenital bilateral corneal opacities, onychodystrophy, and hearing impairment. R-spondin1 is a member of the R-spondin protein family and its pivotal role in sex determination has been recently described. We identified a homozygous splice-donor-site mutation in the RSPO1 gene in our patient. We found that the c.286+1G>A mutation led to an aberrantly spliced mRNA (r.95_286del), which is presumably translated into a partially functional protein (p.Ile32_Ile95del). Our case demonstrates for the first time, to our knowledge, that XX true hermaphroditism can be caused by a single gene mutation. The reported findings represent a further step toward a complete understanding of the complex mechanisms leading to DSDs.

Analysis of candidate genes on chromosomes 5q and 19p in celiac disease

BACKGROUND AND AIM

Celiac disease (CD) is a multifactorial disease with involvement of both environmental and genetic susceptibility factors. The HLA-DQ loci account for <40% of CD heritability, but linkage studies have delineated other loci at the 5q31-33 (CELIAC2), and 19p13 regions (CELIAC4), similarly as in inflammatory bowel diseases. However, data in association studies are contradictory. To evaluate whether single nucleotide polymorphisms (SNPs) tagging the MYO9B susceptibility haplotype and the IBD5 locus (5q31-33) are involved in CD predisposition, we performed case-control and family-based analyses. Additionally, any possible correlation with the HLA-DQ status was investigated. Finally, our data were pooled with the results of other studies by a meta-analysis.

PATIENTS AND METHODS

In all, 337 unrelated patients with CD, 424 parents (212 sets), and 452 healthy individuals were genotyped for the IGR2198a_1, rs12521868, rs1050152, and rs2631367 SNPs (IBD5 locus) and the rs962917, rs2305764, and rs1545620 SNPs of the MYO9B gene by the restriction enzyme method and the TaqMan system ABI PRISM 7700, respectively.

RESULTS

In comparison with healthy control individuals, the allele, genotype, and haplotype frequencies of all investigated SNPs were not different in the CD patients, nor was any correlation observed with the HLA-DQ status or clinical presentation. The transmission disequilibrium test did not show a transmission distortion. Five other studies were available for meta-analysis on MYO9B variants; by pooling of data, no significant association was demonstrated by the random effect model. A significant heterogeneity (P < 0.002) among the studies was present, mainly explained by a single study in the Dutch population.

CONCLUSIONS

Our results and those of the meta-analysis (>2000 CD patients and 4000 control individuals) question the role of MYO9B at the CELIAC4 locus as a disease-causing gene. Moreover, none of the investigated SNPs explain the linkage at the CELIAC2 locus.

Serologic and genetic markers of celiac disease: a sequential study in the screening of first degree relatives

OBJECTIVES

The prevalence of celiac disease (CD) among the relatives and the complications of an undiagnosed CD prompted us to identify a useful disease screening strategy.

METHODS

We studied 441 first degree relatives of 208 CD patients by immunoglobulin (Ig)A antiendomysium antibodies (EMA) and radioimmunoprecipitation assay (RIA) IgA antitransglutaminase autoantibodies (TGAA). Of these, 364 were typed for human leukocyte antigen-DRB1, -DQA1, and -DQB1 genes by the polymerase chain reaction sequence specific primers method. It was suggested to the autoantibody-positive subjects that they should undergo intestinal biopsy.

RESULTS

TGAA were positive in 46 of 439 relatives, EMA in 38; intestinal lesions related to CD were present in 40 subjects. We also found two immunodeficient fathers with duodenal villous atrophy. In three serology-positive subjects, permission for intestinal biopsy was refused; for another three serology-positive cases, duodenal mucosa was normal. Thus, the strict CD prevalence resulted 9.5%, the enlarged prevalence 10.9%. The DQ2/DQ8 heterodimers were carried in 231 of 364 subjects and in 38 of 40 biopsy-proven celiac patients. Three DQ2-positive parents became positive to the serology during a long-lasting follow-up.

CONCLUSIONS

On the basis of a carefully conducted study, CD prevalence in our series was seen as very high. These data suggest an accurate algorithm to select candidates for intestinal biopsy among CD high-risk subjects. First, an evaluation of the sensitive RIA TGAA and of total IgA (in IgA deficiency RIA IgG anti-tissue transglutaminase assay) should be performed. Then, an evaluation of the TGAA and the genetic study would be advisable 2 to 3 years later in negative subjects. Those carrying the DQ2/DQ8 heterodimers should continue the serologic follow-up; the others need a clinical follow-up.

Association of the Matrix Metalloproteinase-3 (MMP-3) Promoter Polymorphism With Celiac Disease in Male Subjects

Matrix metalloproteinases (MMPs), such as stromelysin-1 (MMP-3), are a family of enzymes important in resorption and remodeling of the extracellular matrix whose degradation may play a role in the villous atrophy characteristic of celiac disease (CD). We investigated the association between the polymorphism at position -1171 of the MMP-3 gene and susceptibility to CD in 225 Italian patients and 170 controls previously typed for human leukocyte antigen (HLA) class II genes. We also evaluated sex differences in the effect of this polymorphism on disease risk. A male-specific association of the 5A/6A polymorphism with CD was observed. The frequencies of 6A allele and 6A/6A genotype in affected male subjects were significantly above those observed both in male controls (p = 4.1 x 10(-3) and p = 3.4 x 10(-3); odds ratio = 2.4, 95% confidence interval 1.3-4.3) and in female patients (p = 2.7 x 10(-4) and p = 6.2 x 10(-4)). This is the first demonstration of a sex-specific association between the MMP-3 promoter polymorphism and CD. Homozygosity for the 6A allele appears as a risk factor for CD only in men, which is different from the HLA susceptibility alleles that confer a higher risk in women.

Minor expression of fascin-1 gene (FSCN1) in NTera2 cells depleted of CREB-binding protein

CREB-binding protein (CBP) is a transcriptional coactivator whose mutations may cause a generalized perturbation of gene expression. We silenced the CBP gene in NT2 neuronal precursor cells by RNA interference. Hybridization experiments on 1.2K human cDNA microarrays showed that the FSCN1 gene, encoding for fascin-1 protein, was clearly less expressed in CBP-depleted cells than in controls. This reduction was confirmed by Real Time PCR and Western blotting assays. We also analyzed FSCN1 expression profile during NT2 neuronal differentiation induced by retinoic acid (RA), showing that FSCN1 was up-regulated during neurogenesis. This mRNA increasing suggests the importance of fascin-1 in the formation of mature neurons, in accordance with its actin-bundling function and its localization in neurites and neuronal growth cones. The lower amount of FSCN1 transcript in the absence of the CBP factor was also established in RA-treated cells. In conclusion, this research supports FSCN1 as a novel marker of NT2 neuronal differentiation and the possible role of CBP in its regulation.

Expression of neuronal markers during NTera2/cloneD1 differentiation by cell aggregation method

Human teratocarcinoma NTera2/cloneD1 (NT2) cells are able to generate postmitotic neurons in response to retinoic acid (RA) and for this reason these cells provide an important tool to study human neurogenesis in vitro. We have obtained neurons by treating NT2 aggregated cells with RA for solely 14 days. RT-PCR assays showed that NT2 cells express mRNAs of several neural bHLH genes such as Hes1, Ngn1, Mash1, NeuroD, Math1 and Pax6, just in the early days of RA exposure. In particular, we reported for the first time that RA treatment was followed by a modulation of endogenous Ngn1 and Math1 transcripts. RT-PCR and Western blotting experiments also demonstrated expression of typical neuronal markers such as GluR, MAP2, Tau and NeuN. Knowledge of the expression pattern of the different neuronal genes during NT2 commitment could be used to investigate alterations in the molecular pathways involved in the human neuronal differentiation.

Patchy villous atrophy of the duodenum in childhood celiac disease

OBJECTIVES

Patchy villous atrophy of the duodenal mucosa has been described in adults with untreated celiac disease (CD) but not in children. The authors evaluated the presence and the distribution of villous atrophy in children with celiac disease to see whether this histologic pattern exists in children.

METHODS

We studied 95 children at diagnosis (Group 1) and seven during gluten challenge (Group 2). We measured anti-endomysium antibodies (EMA) by immunofluorescence on monkey esophagus, antihuman-tissue transglutaminase autoantibodies (anti-tTG Abs) by radioimmunoprecipitation, and HLA-DQ2/DQ8 heterodimers by polymerase chain reaction using specific primers. During upper intestinal endoscopy, at least five duodenal biopsy samples were obtained, one from the duodenal bulb and four from the distal duodenum.

RESULTS

Thirteen of 95 (13.7%) patients in Group 1 and in 3 of 7 (42.9%) in Group 2 had patchy villous atrophy of the duodenum. In all 16 patients, villous atrophy of the bulb was present. In four children from Group 1, villous atrophy was observed only in the bulb samples. EMA, anti-tTG Abs, and HLA-DQ2/DQ8 heterodimers were present in all patients. Fourteen of 16 had symptomatic CD, and two were silent, detected during screening in subjects at risk for CD.

CONCLUSIONS

This is the first study demonstrating that children with CD may have patchy villous atrophy of the duodenum. The bulb mucosa may be the only duodenal area involved, both at diagnosis and after gluten challenge. Therefore, multiple endoscopic biopsies should always be performed, not only in the distal duodenum, but also in the bulb.

Absence of in vivo DNA-protein interactions in the DQA2 and DQB2 promoter regions

The DQ subregion of the human major histocompatibility complex (HLA) contains two pairs of loci: the DQA1/B1 genes (hereafter called DQ1), coding for the DQ molecules, and the DQA2/B2 pseudogenes (hereafter called DQ2). These pseudogenes are highly homologous to the functional DQ1 genes and they have no apparent abnormal features in their sequences that could prevent their activity. Only recently a low expression of the DQA2 gene has been observed whereas the DQB2 transcript was never found. The comparison between the DQ1 and DQ2 regulatory sequences revealed several differences in their W, X, and Y cis-acting elements. To examine the DNA/protein interactions in the DQ promoter regions, we performed in vivo footprinting experiments. Whereas the functional DQ1 loci showed a series of DNA-protein contact points in the X and Y boxes, the promoters of the DQ2 pseudogenes displayed an unoccupied phenotype. These findings suggest that the very low level of DQA2 expression and the apparent lack of DQB2 activity are caused by the reduced binding affinity of specific transcription factors.

Search for coeliac disease susceptibility loci on 7q11.23 candidate region: absence of association with the ELN17 microsatellite marker

The involvement of HLA genes in the susceptibility to coeliac disease (CD) has been well documented and represents the only consistently observed genetic feature of this multifactorial disease. In the present study, the search for new susceptibility genes has been devoted to a candidate region suggested by the association of CD with Williams syndrome (WS). This genetic disorder is due to a deletion in the 7q11.23 region that includes the elastin (ELN) gene. An increased prevalence of CD in WS patients has been previously reported and a case of CD-WS is also described in the present study. We used the ELN17 microsatellite marker mapped within the ELN gene to look for a possible contribution of this region to the susceptibility to CD. The analysis of 74 Italian CD families provided no evidence of association with the ELN17 marker.

Strong linkage disequilibrium of TAP1*0301 and TAP2D alleles with the HLA A1-B35-DRB1*1104-DQA1*0103-DQB1*0603 extended haplotype in Ashkenazi Jews

On the basis of data collected during the 12th International Histocompatibility Workshop, we postulated a possible linkage disequilibrium between the TAP1C allele and the DRB1*1104-DQA1*0103-DQB1*0603 haplotype characteristic of Ashkenazi Jews. In order to confirm and extend this preliminary observation, a group of 34 subjects carrying this haplotype was analysed for TAP1 and TAP2 polymorphisms and compared with two control groups sharing either the DRB1 or the DQA1 and DQB1 alleles with the test group. The TAP1*0301 and TAP2D alleles were found to be strongly associated with the entire haplotype, but not with the DRB1*1104 or the DQA1*0103-DQB1*0603 alleles when carried separately. These data show a strong linkage disequilibrium of TAP1*0301 and TAP2D alleles with the DRB1*1104-DQA1*0103-DQB1*0603 haplotype of Ashkenazi Jews, extended on the centromeric and telomeric side to the DPB1*0201 and A1-B35 alleles, respectively.

Molecular prenatal diagnosis of ataxia telangiectasia heterozygosity by direct mutational assays

Ataxia telangiectasia (AT) is a severe autosomal recessive disease, rare but not infrequent in Italy. Owing to the seriousness of the disease, prenatal diagnosis has been attempted in the past by means of cytogenetic, biochemical, radio-biological and indirect molecular analyses. We performed the first direct molecular prenatal diagnosis of AT on a chorionic villi sample from a 37-year-old woman at the 10th week of pregnancy. She had two previous children suffering AT and two induced abortions. At molecular analysis her affected children were compound heterozygotes for mutations 7792C-->T in exon 55 (from the mother) and 8283delTC in exon 59 (from the father). The prenatal diagnosis was performed by two different operators in double-blind form. Mutation 7792C-->T was studied by restriction enzyme analysis using TaqI. Mutation 8283delTC was screened by heteroduplex analysis. The fetus was heterozygous for the mutation 7792C-->T (confirmed by sequencing). In order to verify the possible contamination by maternal DNA, polymorphic loci HLA-DRB1 and HLA-DQA1, together with microsatellite markers D6S259, D11S2000, D11S29, D11S1778 and D11S2179, were examined. All these loci were informative, showing that the fetus received only one allele from each parent. The heterozygosity for ATM mutation 7792C-->T was confirmed by molecular studies after the birth of a healthy male baby.

Different binding of NF-Y transcriptional factor to DQA1 promoter variants

Polymorphism in the HLA-DQA1 promoter (QAP) sequences could influence the gene expression through a differential binding of transcriptional factors. Considering the main role played by the Y-box in the transcription, we focused on the QAP4 variants differing for a G vs A transition from the QAP Y-box consensus sequence. Electrophoretic Mobility Shift Assay using the two Y-box sequences was performed to determine whether this mutation could be reflected in an allele-specific binding of transcriptional factors. Indeed, the NF-Y specific band, recognised by supershift experiments, was clearly observed using the Y-box consensus probe but it was barely detectable with the QAP4 one. On the contrary, two other complexes were found to more strongly interact with QAP4 Y-box in comparison to the consensus sequence. The analysis of a selected panel of HLA homozygous lymphoblastoid cell lines by competitive RT-PCR and by Northern blotting revealed that the DQA1 *0401, *0501,*0601 alleles regulated by the QAP4 promoters were less expressed at the mRNA level than the DQA1* 0201 allele regulated by the QAP2.1 variant. In conclusion, these results show an evident reduction of NF-Y binding to the mutated QAP4 Y-box and a decreased mRNA accumulation of the DQA1 alleles regulated by these variants.

Genetic contribution of the HLA region to the familial clustering of coeliac disease

In order to assess the effect of the HLA region on familiality of coeliac disease (CD), we carried out a study on 121 CD index cases and 325 first degree relatives. The transmission disequilibrium test confirmed the importance of the HLA-DR3 haplotype in CD susceptibility. However, the different distortion found in affected children inheriting maternal or paternal DR3 alleles suggested that the sex of the parent might influence the risk conferred by this haplotype. The increase in risk to siblings of affected individuals relative to the risk in the general population (lambda s) and the contribution of the HLA genes to this clustering (lambda sHLA) have also been estimated. Non-overlapping data from the literature have been collected and combined with our sample to extend such analysis. Then, the percentage contribution of the HLA region to the development of CD among siblings was 36.2%. This result confirms that the HLA genotypes are an important genetic background to CD development but shows that additional susceptibility factors remain to be identified.

Single-strand conformation polymorphism (SSCP) analysis of HLA-DRB1*1101-06

Single-strand conformation polymorphism (SSCP) has been developed as a method for detecting the presence of mutations in a segment of DNA. We applied it to the subtyping of the DR11 group of alleles. The SSCP patterns of DRB1-DR52 group-specific products were defined in cell lines representing the DRB1*1101-06 alleles, using non-denaturing acrylamide gel electrophoresis and silver staining. Only one set of gel electrophoresis conditions was able to discriminate the DR11 alleles tested. The protocol was validated in an analysis of 105 DR11-positive individuals previously typed by oligonucleotides probing. The study demonstrates the suitability of the SSCP technique to define the DRB1*1101-06 alleles, the technique being particularly valuable in confirming and extending the oligotyping of DRB1-DR52 heterozygous samples.

Gluten-sensitive disease with mild enteropathy

BACKGROUND & AIMS

Celiac disease is a permanent gluten intolerance strongly associated with HLA class II antigens and possibly showing milder changes of mucosal architecture. Ten patients with symptoms suggesting celiac disease and serum antiendomysium antibodies with normal mucosal architecture were studied.

METHODS

Immunohistochemical detection of mucosal immune activation and HLA typings were performed.

RESULTS

Mucosal immune activation, with normal mucosal architecture and normal gamma/delta+ intraepithelial lymphocytes counts, was found on a gluten-containing diet. In 3 of 6 patients, multiple biopsy specimens showed one sample with severe villous atrophy. Clinical and immunomorphologic features were strictly gluten dependent. The mucosal immune activation was elicited in vitro by gliadin. Only 4 patients had the typical HLA typing of celiac disease.

CONCLUSIONS

Gluten-sensitive celiac-like symptoms may occur in patients with serum antiendomysium antibodies, apparently normal intestinal mucosa, and HLA typing not commonly associated with celiac disease. These patients should undergo multiple biopsies, and signs of immunologic activation should be sought accurately; in the presence of mucosal immune activation, a trial with a gluten-free diet should be encouraged to detect gluten dependency. In vitro immunologic response of small intestinal mucosa to gliadin may support the diagnosis of gluten-sensitive enteropathy.

Frequency and clinical pattern of celiac disease among siblings of celiac children

To investigate the prevalence and clinical and genetic patterns of celiac disease (CD) among siblings of CD patients, 103 siblings and one twin of 80 celiac children were evaluated by means of their clinical history, physical examination, blood indices of nutritional status, and antigliadin antibodies (AGA). Antiendomysium antibody (AEA) levels were determined in 70 patients and 85 subjects were human leucocyte antigen (HLA) typed. On the basis of clinical or laboratory data or both, 21 siblings (20.2%) were submitted to intestinal biopsy, whereas intestinal biopsy in six siblings with positive serologic screening (AGA IgA or AEA or both) was not performed because of parental refusal. In a high percentage of cases (18%), all on a gluten-containing diet, the intestinal mucosa was atrophic, and CD was subsequently diagnosed. Because we could not submit all the siblings to intestinal biopsy, this figure could underestimate the real prevalence of the disease in our series; consequently, it was not possible to calculate accurately the sensitivity and specificity of AGA and AEA. Nevertheless, AEA (positive in all the nine siblings with mucosal atrophy), followed by AGA IgA, proved to be the best screening for CD. Eighteen of 19 CD siblings showed HLA-predisposing antigens. Among the 19 CD siblings, one showed a typical form with gastrointestinal symptoms, two had short stature, one suffered from recurrent vomiting, and in 15, the disease was clinically silent. On the contrary, among siblings who were first diagnosed (index cases), the majority (73.7%) had a typical form of CD, and no clinically silent cases were observed. We did not find any difference between index cases and CD siblings in food habits and distribution of HLA antigens. In 15 of 18 cases, the sibling diagnosed subsequently was the older one. Finally, the typical form of CD was significantly more frequent among the younger brother than the older. In conclusion, the high prevalence of the silent form of CD in our cases indicates that siblings of CD subjects should always be screened for CD. The combination of AGA IgA and AEA represent a good screening method to use in selecting children for the intestinal biopsy.

Definition of the initial immunologic modifications upon in vitro gliadin challenge in the small intestine of celiac patients

BACKGROUND & AIMS

Mucosal cell-mediated immune response is considered the central event in the pathogenesis of celiac disease. In cultured intestinal explants from celiacs in remission, we have characterized the early stages of gliadin-induced immune activation.

METHODS

Intestinal biopsy specimens (15 treated celiacs and 13 controls) were cultured with gliadin or maize prolamine digests for 24 hours as well as for 1, 2, 4, 6, 8, and 12 hours in some subjects. The expression of immunologic markers was detected by immunocytochemistry.

RESULTS

Gliadin challenge may initiate two parallel pathways, one of which leads to T-cell activation and another that precedes it. Epithelial cells overexpress DR molecules after 1 hour, and in a second stage T lymphocytes become fully activated. Moreover, T lymphocytes migrate in the upper mucosal layers. T lymphocytes that migrate in the higher lamina propria compartments are mainly CD4+ and show markers of activation; migrating intraepithelial lymphocytes are CD8+ and do not express these markers.

CONCLUSIONS

In vitro gliadin challenge is a suitable model to reproduce various immunologic features of celiac lesions; these may be caused by different pathways. The comprehension of these phenomena is essential to clarify the distinctive pathogenic mechanisms leading to disease and may help in defining novel therapeutic approaches.

Distinctive features of the alpha 1-domain alpha helix of HLA-C heavy chains free of beta 2-microglobulin

Only a few monoclonal antibodies are available with a restricted specificity to HLA-C products. In the present report, we demonstrate that antibody L31, previously shown to react with beta 2m-less (free) class I MHC heavy chains, binds to an epitope (residues 66-68 of the alpha 1 domain alpha helix) present on all the HLA-C alleles corresponding to the accepted (CW1 through CW8) serologic specificities, and on a few HLA-B heavy chains sharing with HLA-C an aromatic residue at position 67. Extensive IEF blot testing of HLA homozygous, EBV-transformed B-lymphoid cells indicates that HLA-C molecules are present at significantly lower levels than HLA-B polypeptides not only at cell surface, as previously demonstrated, but also in total cellular extracts. Testing of metabolically labeled HLA-CW1, -CW5, and -CW6 transfectants and HLA homozygous lymphoid cells, particularly HLA-CW1-expressing cells, demonstrates that the L31 epitope is present on a subpopulation of naturally occurring HLA-C molecules distinct from that identified by antibody W6/32 to beta 2m-associated heavy chains. Pulse-chase experiments demonstrate that this epitope is transiently made available to antibody binding at early biosynthetic stages, but becomes hidden upon assembly with beta 2m. Thus, free HLA-C and other Y/F67+ heavy chains are characterized by distinctive antibody binding features in a region (residues 66-68) included in a previously identified HLA-C restricted motif, which has been suggested to be the primary cause of distinctive features of the antigen-binding groove, low affinity for endogenous peptide antigens and beta 2m, and preferential uptake of exogenous peptides, possibly of viral origin. We also show that HLA-CW1 heavy chains, both free and beta 2m associated, acquire sialilation. Free HLA-CW1 heavy chains are expressed at the cell surface even when unsialilated, albeit at low levels.

Polymorphism in the upstream regulatory region of DQA1 gene in the Italian population

Polymorphism in the 5'-upstream regulatory region of the DQA1 gene has been recently described. Using PCR-SSO method and SSCP analysis we have investigated this polymorphism in a group of 111 Italian blood donors which had been oligotyped for DRB1, DQA1 and DQB1 genes. Eight allelic variants were detected. Looking at the relationships among QAP sequences and DQA1 and DRB1 genes, three alternative situations were found: 1. a one-to-one relation between QAP and DQA1 alleles, independently of the other class II genes; 2. the same QAP allele in association with different DQA1-DRB1 haplotypes; 3. the same DQA1 allele with different QAP sequences according to the DRB1 specificity. No unexpected associations with DQB1 gene were found. These results must be interpreted considering that DQA1 and DRB1 genes are transcribed in opposite directions so that the promoter region of DQA1 gene lies between DQA1 and DRB1, close to the former but several hundreds kb away from the latter.

Coeliac disease, enamel defects and HLA typing

The presence of dental enamel defects in coeliac disease and their relation to hypocalcaemia or a particular HLA class in 82 Italian children with coeliac disease was studied. Demarcated opacities or hypoplasia were detected in 23 subjects (group 1) while minimal or no dental lesions were found in the remaining 59 patients (group 2); in 189 normal controls, enamel lesions were significantly less frequent than in patients with coeliac disease (14.8% versus 28.0%; p < 0.005). No statistically significant differences were found for age at diagnosis and calcium concentrations between groups 1 and 2. Regression analysis showed a correlation between age at diagnosis and number of teeth with enamel defects. In our patients, the presence of HLA DR3 antigen significantly increased the risk of dental lesions, while genotype DR5,7 seemed to protect against enamel defects. A logistic regression analysis of the variables age, serum calcium concentrations, number of affected teeth, type of enamel defect and DR antigens showed that only DR antigens discriminated coeliac disease patients with from those without enamel defects.

Different dose effect of HLA-DQ alpha beta heterodimers in insulin-dependent diabetes mellitus and celiac disease susceptibility

To compare the quantitative effect of the DQ alpha beta heterodimers DQ alpha 52 Arg+, beta 57 Asp- and DQ alpha 1*0501, beta 1*0201 on susceptibility to IDDM and CD, we characterized, at the genomic level, the DQ alpha 52 and DQ beta 57 residues of 50 IDDM Italian patients observed in Rome. The results were compared with those of a previous study concerning the oligotyping of DQ dimers in a group of CD children belonging to the same population. Our data confirm that both diseases are primarily associated with HLA-DQ alpha beta heterodimers, but the distributions of the respective susceptible DQA1 and DQB1 alleles in the two diseases were different. In fact, the highest risk of IDDM is for subjects alpha SS, beta SS that could express, by either cis- or trans-association, four susceptible heterodimers and decreases in proportion to the number of these; in regard to CD, the highest risk was found for individuals who carried only one predisposing heterodimer.

A study of Italian pediatric celiac disease patients confirms that the primary HLA association is to the DQ(alpha 1*0501, beta 1*0201) heterodimer

Celiac disease (CD) has been recently reported to be primarily associated with the DQ(alpha 1*0501, beta 1*0201) heterodimer encoded in cis on DR3 haplotype and in trans in DR5,7 heterozygous individuals. The high incidence of DR5,7 heterozygotes, reflecting the high frequency of the DR5 allele in Italy, makes the analysis of the Italian CD patients critical. Polymerase chain reaction-amplified DNA from 50 CD patients and 50 controls, serologically typed for DR and DQw antigens, was hybridized with five DQA1-specific oligonucleotide probes detecting DQA1*0101 + 0102 + 0103, DQA1*0201, DQA1*0301 + 0302, DQA1*0401 + 0501 + 0601, and DQA1*0501 and a DQB1-sequence-specific oligonucleotide probe recognizing DQB1*0201 allele. As expected by the DR-DQ disequilibria, DQA1*0201 [62% in patients versus 26% in controls, relative risk (RR) = 5] and DQA1*0501 (96% versus 56%, RR = 19) show positive association with the disease. Of CD patients, 92% (50% DR3 and 42% DR5,7) compared to 18% of the controls carry both DQA1*0501 and DQB1*0201 alleles, so that the combination confers an RR of 52, higher than both the risks of the single alleles (DQA1*0501 RR = 19, DQB1*0201 RR = 30), confirming the primary role of the dimer in determining genetic predisposition to CD both in DR3 and in DR5,7 subjects.

Oligotyping of Italian celiac patients with the 11th International Histocompatibility Workshop reagents

Oligotyping for HLA-DRB1, DQA1 and DQB1 specificities has been performed on PCR-amplified DNA from 55 Italian celiac children, living in Rome, and 50 blood donors. 52.6% of CD patients were DR3;DQA1*0501;DQB1*0201-positive versus 14% of controls (RR = 6.85) and 34.5% were DR5,7;DQA1*DQB1*0201-positive versus 2% of controls (RR = 25.86). 7 patients (12.7%) were negative for the DQA1*0501/B1*0201 dimer: 3 of them were DR4 (5.4%) and the others typed as DR1,5; 1,7; 5,7 and w6,7. No patient was negative for both DQA1*0501 and DQB1*0201 alleles.

Oligotyping of celiac multiplex families with the 11th International Histocompatibility Workshop reagents

Using PCR and SSO probes from the 11th International Histocompatibility Workshop, we oligotyped for HLA-DRB1 gene and DQA1*0501, DQB1*0201 alleles 10 celiac families each with 2 affected children. All families belong to the Italian population except for one, whose mother is originally from Cape Verde island. 8/10 sibling pairs share the DQA1*0501/B1*0201 heterodimer, inherited in cis or in trans arrangement. All the dimer-negative patients were DR4-positive.

An anti-HLA class I monoclonal antibody alters the progression in the cell cycle of phytohemagglutinin-activated human T lymphocytes

The monomorphic anti-HLA Class I monoclonal antibody 01.65 inhibits the incorporation of tritiated thymidine ([3H]TdR) in Phytohemagglutinin (PHA)-activated human T lymphocytes. Our data indicate that 01.65 affects the average duration of the cell cycle by increasing the length of the early S subphase. As a consequence of the increase in the doubling time of the cell population, the absolute number of cells at harvesting time was reduced in 01.65-treated cultures compared to that of untreated cultures. The lengthening of the S-phase and the decrease in the cell number can together quantitatively account for the reduction of [3H]TdR incorporation observed in 01.65-treated cultures.

Expression of class II MHC antigens in the intestinal epithelium of pediatric celiac disease

Class II MHC antigen expression in the intestinal epithelium of 28 small bowel biopsies from 23 celiac patients were studied by means of indirect immunofluorescence and immunoperoxidase using monoclonal antibodies. Patients were divided on the basis of diet into two subgroups: 15 subjects on a gluten-containing diet (GCD) and 13 on a gluten-free diet (GFD). The control group included 10 pediatric subjects with normal intestinal mucosa who underwent intestinal biopsy for chronic diarrhea or short stature. DR antigens and invariant chain were expressed in all patients, regardless of the diet, as well as in the control subjects. DQ was found in one patient only on GCD. DP antigens were present in 12/15 patients on GCD, and in 2/13 on GFD (Fisher's exact test, p = 8.8 x 10(-4), as well as in 3/10 control subjects. In 4/5 celiac patients, DP antigens, which were undetectable on GFD, could be demonstrated after gluten challenge. The results of the study show that DR antigens are expressed by intestinal mucosa of celiac patients independently of their gluten exposure and that DQ antigens are consistently undetectable. Statistically significant differences in expression of DP antigens on enterocytes of celiac patients on GCD and their neoexpression after gluten challenge may represent a basis for further investigation.

mAb KUL/05 identifies a denaturation-resistant determinant shared by class II MHC products DR, DQ and DP

mAb KUL/05, a novel murine monoclonal antibody, reacts with molecules displaying the typical tissue distribution and molecular profile of class II MHC antigens. An extensive scrutiny employing serological and immunochemical assays on DR homozygous and DR alpha- mutant cell lines has shown that this reagent displays some additional, interesting features, namely mAb KUL/05 (a) binds in a broadly monomorphic fashion to cells of DR1 through seven specificities, (b) recognizes a determinant shared by a large proportion of DR, DQ and DP beta chains from most haplotypes, in both their monomeric and alpha chain-associated forms, and (c) reacts with frozen, acetone-fixed, as well as conventional, formalin-fixed, paraffin embedded tissues. Thus, mAb KUL/05 is likely to represent a useful adjunct for the study of the expression of class II MHC products in normal and pathological tissue specimens.

A study of HLA class II antigens in an Italian paediatric population with coeliac disease

One hundred and twenty-one Italian children with coeliac disease (CD) have been compared with a control population from the same geographical area for the distribution of HLA-DR and DQ antigens. The pattern of an increase in DR3, DR7, and of heterozygotes DR5/7 was associated with an excess of heterozygotes DQw2/DQw3 in the CD population. These findings suggest that epitopes determined by specific combinations of DQ alpha and beta chains (combinatorial determinants) predispose to the disease.

HLA antigens and adult rheumatoid arthritis: a study with a monoclonal antibody

Adult rheumatoid arthritis (RA) is a very heterogeneous disease that is associated with HLA-antigens, although no absolute association has been found with any particular HLA type. Forty-one seropositive RA patients have been studied with a local monoclonal antibody named X1 21.4 (9w940), strongly associated with HLA-DRI, DR4, Drw10 antigens, to verify a possible correlation with the disease. The results obtained have also been compared with the data reported on MC1, a serologically defined determinant correlated with RA. X1 21.4 monoclonal antibody appears to be associated with the disease and it could identify one epitope involved in the susceptibility to RA.

A mouse monoclonal antibody against a polymorphic determinant in a defined subset of DR molecules

The hybridoma technique was used to produce a mouse monoclonal antibody, designated as XI 21.4, which belongs to the IgG2a class. It is active in complement-dependent cytotoxicity and detects a B-cell antigenic determinant associated with DR1, DR4, DRw10, and, possibly, DRw9. Microfingerprinting of the immunoprecipitate from a homozygous DR4 cell line shows a typical alpha DR pattern and a beta pattern coinciding with that of DR4 molecules.

Monoclonal antibodies to HLA-DP-transfected mouse L cells

Mouse L cells transfected with human HLA-DP (DPw4) alpha and beta genes were used to make monoclonal antibodies in C3H mice. A polymorphic antibody, DP11.1, was obtained, as well as several monomorphic antibodies. In ELISAs, DP11.1 bound to DPw4 cells and, more weakly, to DPw2, but not DPw1, -3, -5, or -6, using HLA homozygous cells. It also bound to L-cell transfectants expressing either DPw2 or DPw4 products. From B lymphoblastoid cell lysates labeled with [35S]methionine, the antibody immunoprecipitated alpha and beta chains of a similar size to those precipitated by a well-characterized DP monoclonal antibody, B7/21.2. Immunoblotting indicated that the DP11.1 antibody was directed against the alpha chain. This result confirms partial sequence data that showed that the DP alpha chain, as well as DP beta, is polymorphic, and that DPw2 and -4 alpha chains are very similar, if not identical.

A nonneutralizing human IgM monoclonal antibody inhibiting hemagglutination of H3N2 influenza A strains

A mouse-human hybridoma has been produced by fusing human splenocytes from a Cooley's anemia patient with the murine myeloma P3-NS1/1-Ag 4-1. The hybridoma is stable after 18 months and secretes human IgM. The antibody reacts with some H3N2 influenza A strains and detects an epitope that is part of the hemagglutinin antigen, but does not affect virus infectivity.

A cytotoxic anti-HLA-AB monoclonal antibody which in dilution becomes specific to HLA-A3 crossreacting group

XI 20.4 monoclonal antibody belongs to the IgM class. It precipitates two polypeptide chains characteristic of HLA Class I antigens. At the highest dilutions it is cytotoxic against lymphocytes carrying antigens of the HLA-A3 crossreacting group. Lysostrip experiments show that, at the lowest dilutions, the antibody reacts either with HLA-A, or B antigens.

HLA-ABC and DR antigens in celiac disease. A study in a pediatric Italian population

HLA phenotypes of 64 Italian pediatric patients with celiac disease (CD) were compared with those of a group of healthy controls. DR3 and DR7 are significantly increased as reported in other populations. In addition an increase of heterozygotes DR5/DR7 was observed in our patients. The Hardy-Weinberg distribution in the patients group shows a disequilibrium due to the genotype DR5/DR7. Our data confirm that more than one HLA gene product is associated with CD: one with DR3 and the other with DR7.

A mouse monoclonal antibody detecting the allospecificity HLA-A3

Balb/c mice were immunized with a human B-lymphoblastoid cell line typed HLA-A3, B7. The splenocytes of the immunized mice were fused with a murine myeloma. Supernatants of the cultures were screened against the immunizing cell line in fluorochromasia. Positive cultures were expanded and cloned. One of the clones, X 15.4, was expanded and brought to ascites in Balb/c mice. Monoclonality of the antibody X 15.4, which belongs to the class IgM and immunoprecipitates a molecule of 44000 daltons, was demonstrated by isoelectric focusing. By complement dependent cytotoxicity the ascites only reacted with the lymphocytes of all HLA-A3 individuals from a panel of 146 donors, showing no crossreactions. X 15.4 appears to be one of the very rare xenomonoclonal antibodies suitable for HLA typing.

Delineation of syndromes due to partial 6q imbalances. Trisomy 6q21 leads to qter and monosomy 6q221 leads to qter in two unrelated patients

Two unrelated patients carrying imbalances involving the long arm of chromosome 6 are described. In the first trisomy 6q21 leads to qter had segregated from a maternal translocation t(6;16)(q15;q24). The clinical data of the proposita are compared with those of three other published cases. A partial 6q trisomy syndrome is postulated characterized by: growth deficiency of prenatal onset, psychomotor retardation, craniofacial abnormalities (microcephalia, hypertelorism, downward slanting palpebral fissures, flattened nasal bridge, long philtrum, hypoplastic perioral features, large jaw resulting in a round appearance of the face, receding chin, malformed ears) and dysmorphic extremities (contractures of limbs due to short flexor tendons, hypoplastic fingers, toes and nails). In the second case, monosomy 6q221 leads to qter resulted from a de novo rearrangement and was responsible for mental retardation and facial dysmorphism (reduced biparietal diameter, hypotelorism, absent eyebrows, prominent nose, ptosis, receding chin, dysmorphic ears). Studies of HLA and PGM3 segregation showed normal inheritance patterns and ruled out the location of these genes in bands 6q221 leads to qter.

HLA and chronic active hepatitis

42 patients (33 males and 9 females) with chromic active hepatitis (CAH) mostly HBsAg+, were typed for 24 alleles of the A and B loci. Diagnosis was performed according to the criteria outlined by the European Association for the Study of the Liver. The increased frequency of HLA-A3 (47.6% instead of 19.1% in 266 healthy controls) is significant after correction. The relative risk is 3.83. The phenotypic association A3/Bw35 is also increased (28.5% instead of 6.0 in the control group). The risk of the A3/Bw35 association is 6.25. The risk of A3 calculated in patients lacking Bw35 is 1.6. A family study in 5 patients over 5 showed an haplotype A3/Bw35.