An immunogenetic map of Lombardy (Northern Italy)

DQA1*0102 DQB1*0602 haplotype distinguishes coeliac disease and its complications from gluten unrelated enteropathies

BACKGROUND

Duodenal villous atrophy is due not only to coeliac disease and its complications but also to other rare enteropathies unrelated to gluten consumption, defined as noncoeliac enteropathies. The diagnosis of noncoeliac enteropathies remains challenging, and HLA typing has been widely used to exclude coeliac disease if DQ2 and DQ8 alleles are absent. However, the frequency of the various HLA alleles in noncoeliac enteropathies is still unknown.

AIMS

To describe the HLA genetic profile of patients affected by noncoeliac enteropathies who have been evaluated at our centres between 2000 and 2021, and to investigate the diagnostic role of HLA typing.

METHODS

Genomic DNA was collected from 44 Italian and 19 British adult patients with noncoeliac enteropathies. Patient genotypes were compared with those of healthy Italian and British populations obtained from HLA bone marrow donors' banks. In addition, genotypes were also compared with those of patients with coeliac disease and complicated coeliac disease.

RESULTS

Both in the Italian and in the British group, the DQA1*0102 DQB1*0602 haplotype and related alleles occurred significantly more frequently in patients with noncoeliac enteropathies compared to coeliac disease and complicated coeliac disease.

CONCLUSIONS

Together with negative HLA-DQ2 and DQ8 haplotypes, the DQA1*0102 DQB1*0602 haplotype can be used to guide the differential diagnosis between coeliac disease and noncoeliac enteropathies.

Influence of HLA-DQ2 and DQ8 on severity in celiac Disease

BACKGROUND

HLA-DQB1*02 homozygosity was shown to be more common in patients with complicated rather than uncomplicated celiac disease (CD).

GOALS

To study HLA-DQA1 and DQB1 profile in adult patients with different forms of CD, including patients with complicated and potential CD, the most affected and the most preserved histologic end of the pathologic celiac spectrum.

STUDY

HLA-DQA1 and DQB1 molecular typing was performed in 218 adult CD patients (169 with uncomplicated CD, 27 with complicated CD, and 22 with potential CD) and 224 healthy stem cell donors. HLA-DQA1 and DQB1 gene polymorphism was analyzed using polymerase chain reaction sequence-specific primers and/or reverse polymerase chain reaction sequence-specific oligonucleotides techniques.

RESULTS

As expected, the frequency of HLA-DQB1*02 allele, DQB1*02 homozygosity, and DQB1*0302 gene were statistically different in the 4 groups. However, multivariate analysis demonstrated that patients with potential CD have a higher frequency of both HLA-DQB1*0302 and HLA-DQB1*0603 alleles and a reduced frequency of DQB1*02 homozygosity compared with patients with uncomplicated and complicated CD.

CONCLUSIONS

The increased frequency of DQB1*0302 and the reduced frequency of DQB1*02 homozygosity in potential CD is consistent with the idea that different clinical/pathologic evolutions might be related to different immunogeneses. This could be clinically relevant in the future.

Autoimmunity and Turner's syndrome

Turner Syndrome (TS) is a common genetic disorder, affecting female individuals, resulting from the partial or complete absence of one sex chromosome, and occurring in approximately 50 per 100,000 liveborn girls. TS is associated with reduced adult height and with gonadal dysgenesis, leading to insufficient circulating levels of female sex steroids and to infertility. Morbidity and mortality are increased in TS but average intellectual performance is within the normal range. TS is closely associated to the presence of autoantibodies and autoimmune diseases (AID), especially autoimmune thyroiditis and inflammatory bowel disease. Despite the fact that the strong association between TS and AID is well known and has been widely studied, the underlying immunopathogenic mechanism remains partially unexplained. Recent studies have displayed how TS patients do not show an excess of immunogenic risk markers. This is evocative for a higher responsibility of X-chromosome abnormalities in the development of AID, and particularly of X-genes involved in immune response. For instance, the long arm of the X chromosome hosts a MHC-locus, so the loss of that region may lead to a deficiency in immune regulation. Currently no firm guidelines for diagnosis exist. In conclusion, TS is a condition associated with a number of autoimmune manifestations. Individuals with TS need life-long medical attention. As a consequence of these findings, early diagnosis and regular screening for potential associated autoimmune conditions are essential in the medical follow-up of TS patients.

The HLA alleles DRB1*13 and DQB1*06 are associated to Whipple's disease

BACKGROUND & AIMS

Whipple's disease is a systemic, chronic, relapsing disorder caused by a combination of environmental (Tropheryma whipplei) and unknown host factors. Because it is a rare disease, the association between HLA type and Whipple's disease has been studied in only small numbers of patients; these studies have led to conflicting results. We aimed to investigate whether disease phenotype and outcome are associated with HLA type in 122 patients with Whipple's disease.

METHODS

Genomic DNA was collected from 103 German, 11 Italian, and 8 Austrian patients with Whipple's disease, along with 62 healthy Austrian workers exposed to T whipplei (14 stool samples contained the bacterium). HLA class I and II alleles were identified by polymerase chain reaction analysis. Patient genotypes were compared with those of healthy German and Austrian populations; data for Italian controls were obtained from the Pavia HLA bone marrow donors' bank.

RESULTS

HLA-DRB1*13 and DQB1*06 alleles occurred significantly more frequently in patients with Whipple's disease but not in healthy individuals who had been exposed to T Whipplei. The cumulative odds ratios for disease were 2.23 for the DRB1*13 allele (P < .0001) and 2.25 for the DQB1*06 allele (P < .0001).

CONCLUSIONS

DRB1*13 and DQB1*06 alleles were found to be risk factors in the largest HLA study ever performed in patients with Whipple's disease.

Killer cell immunoglobulin-like receptor genotype and killer cell immunoglobulin-like receptor-human leukocyte antigen C ligand compatibility affect the severity of hepatitis C virus recurrence after liver transplantation

In 20% to 30% of infected individuals, hepatitis C virus (HCV) can cause cirrhosis and hepatocellular carcinoma, for which liver transplantation is the best treatment available. HCV re-infection is universal, and hepatitis disease recurrence occurs in most cases with a 30% probability of progression to graft cirrhosis at 5 years post-transplant. The immunological response to HCV involves natural killer (NK) cells and killer cell immunoglobulin-like receptors (KIRs), which specifically recognize human leukocyte antigen (HLA) class I antigens present on target cells. The effector functions of NK cells are influenced by inhibitory KIR interaction with self-HLA class I ligands, with HLA-C being the most predominant. This study examines the roles of KIR genotypes and their HLA ligands in both HCV disease recurrence and its progression. A total of 151 patients were included in the cohort, and their clinical details were recorded. Liver biopsies were used to define the absence/presence of recurrent hepatitis, the degree of fibrosis, and the progression to cirrhosis over a 10-year period. Mismatching of KIR-HLA-C ligands between donor-recipient pairs was associated with the recurrence of hepatitis (P = 0.008). The presence of KIR2DL3 in the recipient correlated with progression to liver fibrosis (P = 0.04). The mismatching of HLA-KIR ligands favored the progression of the recurrent hepatitis to fibrosis only in the presence of KIR2DL3 (P = 0.04). These preliminary results indicate that the KIR genotype and KIR-HLA-C ligand compatibility play roles in the recurrence and progression of hepatitis C disease in liver transplant recipients.

HLA genes and surnames show a similar genetic structure in Lombardy: Does this reflect part of the history of the region?

Lombardy, in northern Italy, is the most populated and industrialized Italian region. We attempt to study its genetic structure with two independent sets of data: HLA allele frequencies and surnames. According to our results, it is plausible to deduce that ancient history, more than genetic isolation and drift, may have contributed to the present genetic structure of Lombardy. The hypothesis seems to be confirmed by the results of the cluster analysis of the 11 provinces of the region, which was performed using two different types of markers. Both genes and surnames show approximately the same structure. Not only Celts but also ancient Ligurians (and Etruscans) probably shaped the region into the present three clusters in which the 11 provinces appear to be genetically structured. In particular, an ancient historic, archaeological, and linguistic boundary, along the Adda River, seems to be preserved in present-day Lombardy's population structure.

Inferred HLA Haplotype Information for Donors From Hematopoietic Stem Cells Donor Registries

Human leukocyte antigen (HLA) matching remains a key issue in the outcome of transplantation. In hematopoietic stem cell transplantation with unrelated donors, the matching for compatible donors is based on the HLA phenotype information. In familial transplantation, the matching is achieved at the haplotype level because donor and recipient share the block-transmitted major histocompatibility complex region. We present a statistical method based on the HLA haplotype inference to refine the HLA information available in an unrelated situation. We implement a systematic statistical inference of the haplotype combinations at the individual level. It computes the most likely haplotype pair given the phenotype and its probability. The method is validated on 301 phase-known phenotypes from CEPH families (Centre d'Etude du Polymorphisme Humain). The method is further applied to 85,933 HLA-A B DR typed unrelated donors from the French Registry of hematopoietic stem cells donors (France Greffe de Moelle). The average value of prediction probability is 0.761 (SD 0.199) ranging from 0.26 to 1. Correlations between phenotype characteristics and predictions are also given. Homozygosity (OR = 2.08; [2.02-2.14] p <10(-3)) and linkage disequilibrium (p <10(-3)) are the major factors influencing the quality of prediction. Limits and relevance of the method are related to limits of haplotype estimation. Relevance of the method is discussed in the context of HLA matching refinement.

Microgeographic variation of HLA-A, -B, and -DR haplotype frequencies in Tuscany, Italy: implications for recruitment of bone marrow donors

HLA-A/B haplotype frequencies were estimated in a sample of 2355 bone marrow donors born in a subregion of Tuscany (Italy), and the HLA-A, -B, -DR haplotype frequencies were estimated in a subset of 809 individuals. This area was divided in 10 subsamples (two-locus haplotypes), or six subsamples (three-locus haplotypes), all with sample size >50, based on administrative boundaries. A considerable level of heterogeneity of haplotype frequency was present among subsamples; this heterogeneity was associated to a large variation (up to 4-fold) of the number of new donors that must be typed in order to reach 50% chance of finding an HLA-A, -B phenotype of intermediate frequency. Knowledge of the genetic structure of the population at a microgeographic level may be useful in directing the search of specific bone marrow donors.

Analysis of the French National Registry of unrelated bone marrow donors, using surnames as a tool for improving geographical localisation of HLA haplotypes

The first statistical analysis of the French National Registry of volunteer bone marrow donors estimated the probabilities of haplotype frequencies separately for each of the 20 administrative regions of France. Here we propose to use donors' surnames to increase the accuracy of location of the donor's geographical origin. This approach allows us to estimate haplotype frequencies for administrative entities (90 departments) smaller than regions and to correct for bias resulting from recent mobility. We analysed 30,777 donors typed for HLA-A,B and 17,745 donors typed for HLA-A,B,DR,DQ. By using the donors' surnames, we identified common and rare haplotypes (those found in only one department) and estimated the degree of HLA polymorphism at the department level. We also identified departments with a distinctive genetic structure (for example, Paris, Corsica, Pyrenees and Meurthe-et-Moselle). By providing a more accurate geographical distribution of HLA polymorphisms in France, this study will enable us to optimise policies for recruiting bone marrow donors and to improve the fit between the donor file and patients' needs.