Description of four new HLA alleles in the Finnish population: A*03:283N, A*68:167, C*03:327, C*03:361.

New HLA alleles found in the Finnish population: A*03:283N, A*68:167, C*03:327 and C*03:361.

The mouse tie receptor tyrosine kinase gene: expression during embryonic angiogenesis.

Angiogenesis, the process by which new blood vessels are formed, is essential in reproduction, development, wound repair and oncogenesis. Endothelial receptor tyrosine kinases are likely to play key roles in the intercellular signalling controlling angiogenesis. We have here analysed the expression of the endothelial receptor tyrosine kinase tie during the earliest stages of vascular development. The mouse tie cDNA was isolated and sequenced and the exon structure of the coding region was determined. The part of the tie gene encoding the extracellular domain was found to be organized in exons specifying the characteristic domains of the Tie polypeptide. Early postimplantation mouse tissues were analysed for tie expression by in situ hybridization. No tie mRNA was detected in 7.5 day mouse embryos. In 8.5 day embryos, tie expression was observed in differentiating angioblasts of the head mesenchyme, in the splanchnopleure and dorsal aorta as well as in migrating endothelial cells of the developing heart. A weak tie signal was also obtained from angioblasts in the blood islands of the yolk sac. Furthermore, tie mRNA was prominent in the endocardium of the embryo and in the endothelial cells forming the lung vasculature. Expression of tie persisted in the lung capillaries of adult mice, but was decreased in the endocardium. These results suggest that the tie receptor tyrosine kinase is involved in angiogenesis and/or maintenance of endothelial cell functions.

The human TYRO3 gene and pseudogene are located in chromosome 15q14-q25.

Partial cDNAs of the human TYRO3 gene, encoding a putative receptor tyrosine kinase, and its processed pseudogene (TYRO3P) were cloned from human teratocarcinoma cell, bone marrow and melanocyte cDNA libraries. The tyrosine kinase homologous domains of TYRO3 and TYRO3P were sequenced and compared with each other and with the mouse TYRO3 gene. Abundant levels of the 4.2-kb TYRO3 mRNA were detected in human brain, and lower levels in other human tissues. TYRO3 and TYRO3P were both assigned to human chromosome 15q14-q25 by analysis of DNAs from somatic cell hybrids.

Celiac patients predominantly inherit HLA-DPB1*0101 positive haplotype from HLA-DQ2 homozygous parent.

The DQA1*0501 and DQB1*0201 alleles (hereafter DQ2) confer genetic susceptibility to celiac disease (CD). Some studies have indicated that the DPB1, DMB, and TAP loci, that are located close to the DQ genes, could also together with DQ or independently confer genetic susceptibility to CD. Some others have claimed that these associations result merely from linkage disequilibrium, a hallmark of the MHC, that often makes the precise mapping of susceptibility genes difficult. To evaluate further the role of class II genes in CD, we analyzed segregation of DPB1 alleles in families with CD. In particular, we analyzed families where one of the parents was homozygous for the DQ2 risk allele but heterozygous for DPB1*0101, an allele claimed to be an additional risk allele. We reasoned that if DPB1*0101 would not play a role in CD, then patients should inherit the DQ2 haplotypes randomly from a homozygous parent. We here present evidence that, in all 6 informative families, those DQ2 positive haplotypes that also include the DPB1*0101 allele, rather than those without DPB1*0101, are predominantly segregated to the index patient from the parent homozygous for the DQ2 risk marker (p = 0.03 as compared to their healthy siblings). If confirmed in larger studies the results indicate that despite DQ2 other genes in or near the MHC may associate with CD.

HLA-DQ2-negative celiac disease in Finland and Spain.

Genetic susceptibility to celiac disease (CD) is strongly associated with DQA1*0501 and DQB1*02 (= DQ2). To study whether CD patients without DQ2 share other MHC class II or TNF alleles, we screened DQ2-negative patients in Finland and Spain. Twelve of 84 (14%) Finnish patients and 13 of 189 (6%) Spanish patients were negative for DQ2. We observed that all but two of altogether 25 DQ2-negative patients had the DR4 DQ8 haplotype, or either DQA1*0501 or DQB1*02 alone. Also, all but three were positive for DRB4*01. The only patients without any of these alleles were both positive for DR 13. There was a clear difference between Finland and Spain: Ten (83%) of the 12 Finnish DQ2-negative patients but only five (38%) of the 13 Spanish patients had DRB1*03, DQA1*03, DQB1*0302 (= DQ8) alleles. Of the Spanish patients, eight (62%) had DQB1*02 without DQA1*0501 and three (23%) had DQA1*0501 without DQB1*02. None of the TNF, TAP, or DPB1 alleles was found to be significantly associated with CD. Our results indicate that in addition to the DQ2 heterodimer, the other major risk alleles for CD are DR4 DQ8, and either DQA1*0501 or DQB1*02 alone. Patients without these alleles appear to be very rare, only two (0.7%) were identified in altogether 253 patients tested.

Shared loci for migraine and epilepsy on chromosomes 14q12-q23 and 12q24.2-q24.3.

OBJECTIVES: To describe clinical characteristics and to identify susceptibility loci for epilepsy and migraine in a Finnish family with a complex phenotype. METHODS: Participating family members were interviewed and medical files were reviewed. The seizure classification was made according to International League Against Epilepsy criteria. Migraine diagnosis was made using the validated Finnish Migraine Specific Questionnaire for Family Studies and criteria according to the current International Classification of Headache Disorders-II. DNA samples were obtained from 56 family members and nonparametric genome-wide linkage analyses were performed using 382 polymorphic microsatellite markers. The most promising loci were fine-mapped with additional microsatellite markers. RESULTS: Clinical data were obtained from 60 family members of whom 12 (20%) had idiopathic epileptic seizures. Eight of those 12 (67%) also had migraine. Altogether 33 of the 60 family members (55%) had migraine. Significant evidence of linkage was found between a locus on 14q12-q23 and migraine (p = 0.0001). Suggestive evidence of linkage in this region was also found for epilepsy with generalized tonic-clonic seizures (p = 0.0034). In addition, significant evidence of linkage was found at a locus on 12q24.2-q24.3 (p < 0.001) for migraine alone and for the combined phenotype of migraine and epilepsy. CONCLUSIONS: Our data suggest the occurrence of common susceptibility loci for epilepsy and migraine on chromosomes 14q12-q23 and 12q24.2-q24.3, implicating a shared genetic etiology for these 2 diseases.

GLUT1 mutations are a rare cause of familial idiopathic generalized epilepsy.

OBJECTIVE: The idiopathic generalized epilepsies (IGE) are the most common genetically determined epilepsies. However, the underlying genes are largely unknown. We screened the SLC2A1 gene, encoding the glucose transporter type 1 (GLUT1), for mutations in a group of 95 European patients with familial IGE. METHODS: The affected individuals were examined clinically by EEG and brain imaging. The coding regions of SLC2A1 were sequenced in the index cases of all families. Wild-type and mutant transporters were expressed and functionally characterized in Xenopus laevis oocytes. RESULTS: We detected a novel nonsynonymous SLC2A1 mutation (c.694C>T, p.R232C) in one IGE family. Nine family members were affected mainly by absence epilepsies with a variable age at onset, from early childhood to adulthood. Childhood absence epilepsy in one individual evolved into juvenile myoclonic epilepsy. Eight affected and 4 unaffected individuals carried the mutation, revealing a reduced penetrance of 67%. The detected mutation was not found in 846 normal control subjects. Functional analysis revealed a reduced maximum uptake velocity for glucose, whereas the affinity to glucose and the protein expression were not different in wild-type and mutant transporters. CONCLUSION: Our study shows that GLUT1 defects are a rare cause of classic IGE. SLC2A1 screening should be considered in IGE featuring absence epilepsies with onset from early childhood to adult life, because this diagnosis may have important implications for treatment and genetic counseling.

TNF microsatellite alleles a2 and b3 are not primarily associated with celiac disease in the Finnish population.

Recently, an independent association between tumor necrosis factor (TNF) gene polymorphism and celiac disease was observed in the Irish population. We tested this association in Finnish patients with celiac disease. The TNF microsatellite alleles a2 and b3 were strongly associated (Pcorr<0.0001 for both) with celiac disease when the patients were compared to the random population. However, when the comparison was made with the DQ2-matched controls, no association could be found. We therefore conclude that in Finland the TNFa2 and b3 alleles are associated with DQ2-positive haplotypes rather than celiac disease.

Circulating T lymphocyte subsets in coeliac disease (CoD) patients and healthy family members.

Increased proportions of circulating antigen-primed CD45RO+ TCR gammadelta cells have been found in untreated CoD patients. As certain immunological features are now found in both CoD and healthy persons carrying the HLA DQ2 heterodimer, we sought to establish whether healthy members of the families of CoD patients who are positive for HLA DQ2 and also have increased densities of TCR gammadelta intraepithelial lymphocytes (IEL) in their small bowel mucosa have elevated levels of circulating TCR gammadelta memory cells. Peripheral blood T cells were analysed by flow cytometry in 22 patients with CoD and 16 healthy family members. Untreated CoD patients had higher percentages of circulating CD45RO+ TCR gammadelta cells and CD45RO+ Vdelta1+ cells than healthy family members. On the other hand, the amount of circulating Vdelta1+ lymphocytes was lower in patients with CoD compared with healthy family members. In contrast, no differences were found between HLA DQ2+ and HLA DQ2- healthy family members in respect of circulating TCR gammadelta cell subsets. The change in circulating TCR gammadelta cell subsets found in patients with CoD is thus a consequence of an ongoing immunological process which diminishes on a gluten-free diet rather than a phenomenon directly caused by DQ2. These changes in peripheral blood are not found in healthy individuals who have the same HLA alleles DQA1*0501 and DQB1*0201 encoding the HLA DQ2 and who also have increased densities of TCR gammadelta IEL in their otherwise normal jejunal mucosa.

HLA DQ and DP in Finnish families with celiac disease.

We studied DQA1, DQB1, and DPB1 alleles in 31 Finnish families with celiac disease (CD). All healthy first-degree relatives underwent clinical investigation, including in most cases biopsy, to establish whether clinically silent CD was present. Our results indicate that all patients, having either full clinical CD or its silent form, had the susceptibility alleles DQA1*0501 and DQB1*0201. The different clinical outcomes of CD were therefore not directly determined by the DQ alleles. The frequency of DPB1*0101 was also higher in CD patients, but the association appeared secondary to those of DQA1*0501 and DQB1*0201 (DQ2). The primary association of CD with the DQA1*0501 and DQB1*0201 alleles, rather than with HLA haplotypes, was confirmed in multiplex families.

Distinct immunologic features of Finnish Sjögren's syndrome patients with HLA alleles DRB1*0301, DQA1*0501, and DQB1*0201. Alterations in circulating T cell receptor gamma/delta subsets.

OBJECTIVE: To determine whether there were differences in the circulating T lymphocyte subsets or clinical features of patients with primary Sjögren's syndrome (SS) who were positive for different HLA alleles. METHODS: Two- and three-color flow cytometry analyses were performed, using a whole blood lysing method. RESULTS: Patients with SS who had the HLA alleles DRB1*0301, DQA1*0501, and DQB1*0201 had lower levels of circulating V delta 1-positive T cell receptor gamma/delta (TCR gamma/delta) cells and higher levels of circulating CD45RO-positive TCR gamma/delta cells compared with patients with SS who did not have these alleles. The patient subgroup with these alleles also had higher levels of anti-SS-A/Ro and anti-SS-B/La. CONCLUSION: These results indicate that patients with primary SS may be immunologically divided into subgroups according to their HLA status. These immunologic changes in SS may also be typical of other autoimmune disorders in patients with the HLA-DR3 haplotype.

Celiac disease and markers of celiac disease latency in patients with primary Sjögren's syndrome.

OBJECTIVE: Many autoimmune diseases occur concomitantly with celiac disease. We investigated prospectively the occurrence of celiac disease and small-bowel mucosal inflammation in patients with primary Sjögren's syndrome. METHODS: A total of 34 patients with primary Sjögren's syndrome and 28 controls underwent small bowel biopsy. Villous morphology, jejunal intraepithelial lymphocytes, and mucosal HLA-DR were evaluated and DQA and DQB alleles, serum antiendomysial, and antigliadin antibodies were examined. RESULTS: Five (14.7%) of 34 Sjögren's syndrome patients were found to have celiac disease. The density of jejunal intraepithelial gammadelta+ T cells was increased in all celiac and in four nonceliac patients. All celiac patients, 69% of nonceliac Sjögren's syndrome patients, and 11% of control subjects showed enhanced HLA-DR expression (p < 0.001). HLA DQ2 was present in 19 (56%) patients with Sjögren's syndrome, including all five with celiac disease. CONCLUSIONS: The findings show a close association between Sjögren's syndrome and celiac disease. Even among nonceliac patients with primary Sjögren's syndrome, an ongoing inflammation is often present in the small bowel mucosa.

Canine major histocompatibility complex genes DQA and DQB in Irish setter dogs.

Information about genetic variation within the canine major histocompatibility complex (MHC) class II genes is limited. In common with most other vertebrate species the canine MHC, or DLA, includes genes which are homologous to human DR, DQ, and DP. Recently, at least one functional DLA DQ gene-pair has been characterized, but so far systematic screening efforts have been lacking. In the present study, we sequenced both cDNA and genomic clones derived from DLA DQ genes of Irish setter dogs. This breed was of interest, since it shows a high prevalence of gluten sensitive enteropathy (GSE), which may be a useful animal model for celiac disease (CD) of man. Interestingly, few of the alleles found in Irish setters were identical to those previously detected in other breeds. Three novel DLA DQA and four novel DLA DQB alleles were discovered in 19 unrelated dogs. Strong association between certain HLA DQ alleles and CD of man prompted us to screen the DQ alleles of members of a family of gluten-sensitive Irish setter dogs. No haplotypes or alleles were shared by all affected dogs, but one frequent haplotype in this family was also detected in an unrelated gluten-sensitive Irish setter; this haplotype was absent in the healthy dogs. This observation warrants further investigation by screening the DQ alleles of a large population of unrelated gluten-sensitive Irish setters.

Genetic susceptibility to gluten sensitive enteropathy in Irish setter dogs is not linked to the major histocompatibility complex.

Gluten sensitive enteropathy (GSE) in Irish setter dogs has been proposed as an animal model for human celiac disease (CD), in which the major histocompatibility complex (MHC) class II alleles HLA DQA1*0501 and DQB1*0201 play an important role. To investigate whether an orthologous MHC class II region is involved in canine GSE, we undertook a linkage study in two large families of gluten sensitive Irish setter dogs. A total of 44 dogs in these pedigrees were genotyped for DQA1, DQB1 and C.2202 alleles, along with 30 unrelated healthy Irish setters. No genetic linkage between the DQ or C.2002 loci and GSE was detected. In contrast to CD, susceptibility to canine GSE does not appear to be determined by variation within the MHC class II gene cluster. Therefore, canine GSE may not be an appropriate model for CD, but nevertheless remains an important disease for advancing knowledge of pathological processes in the intestine.

Nomenclature for factors of the dog major histocompatibility system (DLA), 1998: first report of the ISAG DLA Nomenclature Committee.

A Nomenclature committee for Factors of the Dog Major Histocompatibility System or Dog Leukocyte Antigen (DLA) has been convened under the auspices of the International Society for Animal Genetics (ISAG) to define a sequence based nomenclature for the genes of the DLA system. The remit of this committee includes: assignment of gene names rules for naming alleles assignment of names to published alleles assignment of names to new alleles rules for acceptance of new alleles DLA Nomenclature Committee, rules for acceptance, DLA genes and alleles, sequence based nomenclature.

Nomenclature for factors of the dog major histocompatibility system (DLA), 1998. First report of the ISAG DLA Nomenclature Committee. International Society for Animals Genetics.

A Nomenclature Committee for factors of the dog major histocompatibility system or dog leukocyte antigen (DLA) has been convened under the auspices of the International Society for Animal Genetics (ISAG) to define a sequence-based nomenclature for the genes of the DLA system. The remit of this committee includes: i) assignment of gene names; ii) rules for naming alleles; iii) assignment of names to published alleles; iv) assignment of names to new alleles; and v) rules for acceptance of new alleles.