Study On The Correlation Between The Polymorphism Of HLA-DRB1,-DQB1 Alleles And Susceptibility To The Familial Asymptomatic Central Nervous System Demyelinating Disease

Objective:The CNS demyelinating disease is a autoimmune disease with complex causes and varies in clinical manifestations. The CNS demyelinating disease revealed itself by the demyelination of nerve axon while the nerve cell and axis cylinder remain intact. The myelin sheath that cover the axon provide protection and helps conducting nerve impulses. The degeneration and necrosis of the myelin sheath caused by any causes could lead to nerve function compromising, which could be observed in clinic and dignosed as CNS demyelinating disease. In the field of the study of CNS demyelinating disease, MS hold the most. In all the Genetic studies of MS, family relationship of HLA gene indicates that the MS is Genetic tendency, which explains the morbidity of MS is more common in patient’s family. Although HLA gene is confirmed to be the most important Genetic factor of MS[1], due to the variety of races and regions, the conclusion is not exactly the same or even opposite. HLA gene is closely related to the process of immune response, its main function are antigen presentation and HLA restriction. Former studies have proved that HLA-II related disease could lead to immunoregulation problem, especially HLA-DRB1 strong associated disease, revealed by chronic disease, inflammation, immune dysfunction and Genetic predisposition[2]. The study on the familial aggregation of the susceptible gene of CNS demyelinating disease is rare in domestic so far. Therefore, we conducted PCR- SSP to study the the association between the polymorphism of HLA-DRB1,-DQB1 allele and susceptibility to CNS demyelinating disease of 13 patients from the two families in Chengde.Method:1 The research object:1.1 There are 13 patients in these 2 families are found as the patient group in chengde medical university affiliated hospital neurology with demyelinating disease of the familial asymptomatic from 2007.9 to 2012.11. In this study,we tracked 50 persons in this 2 families,in which there are 13 patients with similar symptoms and imaging findings. The majority of patients’ onset is subacute or chronic in the middle age, without obvious history of precursor infection.Most patients have not obvious clinical symptoms except for the occasional dizziness, headache, slight memory loss compared with the previous and so on. They have not typical clinical feature. There are multiple point or patchy abnormal signals can be found in the Bilateral cerebral hemisphere white matter in the imagings(Fig.3,4,5), presenting a demyelinating performance, comprehensively diagnose as demyelinating disease. Most of the patients have no obvious progress in Illness development since 2007. On checking out of cerebrovascular disease, leukodystrophy, classic MS(do not conform to the 2010 Mc Donald diagnostic criteria [3] of MS), RIS and other possibilities, they have no other family disease history, either,therefore temporarily defined as the familial asymptomatic CNS demyelinating disease. There are 7 males and 6 females, age ranging from 37-56, Avg.49.1.2 33 healthy cases were enrolled after fully check ruling out nerve system disease, Hereditary disease and Autoimmune diseases. Systematic random sampling was conducted with age and gender composition following case group by Similar principles. Both groups`cases are Han nationality. The difference between age and gender composition shows no Statistical significance(P>0.05).The study was approved by the ethics committee, all subjects were informed and signed the informed consent.2 The research methods2.1 Collection, sorting and analysis of clinical data: Collecting and sorting the itating factors, onset form, first symptoms, affected areas and MRI images of the 13 patients with the familial asymptomatic CNS demyelinating disease in these 2 families.2.2 Sample collection: Blood sampleing was drawed in the morning after 12-14 hours of fasting on each participant. The samples were EDTA anticoagulant and centrifuged, then collected the white WBC layer.The WBC samples were stored in refrigerator at- 20 ℃. PCR-SSP was conducted to test the polymorphisms and allele frequencies of HLA-DRB1,-DQB1 genes.2.3 Draw the pedigree chart: Using the data of tracking survey,data analysizing and gene detection to draw the pedigree chart of the 2 families.Using the pedigree chart to analysis furtherly if this disease is genetic tendency and to locate the susceptible gene.3 Statistical analysisUsing χ2 test or continuous calibration test(20% above theoretical value, 1 < T < 5, N > 40) to analysis the HLA-DRB1,-DQB1 gene frequency of the aptient group and control group in SPSS17.0 statistical software in the statistic analysis. P < 0.05 is significant.Result:1 Gene polymorphisms of HLA-DRB1,-DQB11.1 Compare 33 healthy controls with 13 patients from the 2 families to exam the SSP genetic types, 12 different types of HLA-DRB1 are found(HLA-DRB1*01、*03、*04、*07、*08、*09、*10、*11、*12、*13、*14、*15); and 5 types of HLA-DQB1 are found(HLA-DQB1*02、*03、*04、*05、*06). Among all the patients 6 types of HLA-DRB1(HLA-DRB1*07、*08、*09、*11、*14、*15) and 4 types of HLA-DRB1(HLA-DQB1*02、*03、*05、*06)were found.(Table 1 and 2)1.2 The result of the test of the HLA-DRB1,-DQB1 gene polymorphisms from each family comply with the gene separation law and gene combination law. Each sample’ HLA-DRB1,-DQB1 gene comply with the correlation between HLA- DR and HLA – DQ.(Fig.11)2 Analysis on the correlation between the polymorphism of HLA-DRB1,-DQB1 alleles and the familial asymptomatic CNS demyelinating disease.(Table 1 and 2)2.1 The gene frequency of HLA- DRB1*14 in experimental group and control group is 38.46% and 9.10%, the difference is statistical significant(χ2=11.715,P=0.001<0.05).2.2 Other alleles compare with the control group’s show no statistical significance(P > 0.05).Conclusion:1 Most onset of demyelinating disease are subacute or chronic with no obvious incentive. Demyelination is a result of both environmental and genetic factors, which can be diagnosed in the early phase by the abnormal signal in brain white matter of MRI.2 HLA-DRB1*14 gene could be the susceptible gene of the two families in Chengde area. This gene could have genetic tendency, which is similar to the majority opinion that Environmental and genetic factors could cause Demyelination. However, if the HLA-DRB1*14 is connected with the two families` demyelination is yet to be studied furtherly.3 This study shows no connection of HLA-DRB1*15 and asymptomatic CNS demyelinating disease in Chengde area, which differs from the reports of Western,Japan and southern China.4 Gnen types of HLA-DQB1 shows no significant expression in CNS demyelinating disease,this conclusion is different from a study in Shanghai[31] which show that the allelic of HLA-DQB1*0502 is relative with MS in Shanghai area.5 All the outcome of this study indicate that the CNS demyelinating disease could be genetic heterogeneity.