BRITISH BIOMEDICAL BULLETIN

Aims and objectives: Type 1 Diabetes Mellitus (T1DM) is characterized by the presence of auto-antibodies, self-reactive T-cells. Measurement of islet autoantibodies can assist in the diagnosis of the disease, and the detection of auto-antibodies in non-diabetic individuals indicate that they are at high risk of subsequent development of the disease. Materials and methods: This study is a cross sectional study which aims to determine the frequency of anti-glutamic acid decarboxylase autoantibodies (GADA) and anti-insulin autoantibodies (IAA) in patients with T1DM and their siblings in AL-Thawrah Hospital, Taiz city, Yemen. It was conducted from June to December 2005. Blood samples were collected from 44 T1DM patients, 52 siblings and 16 controls. Sera were obtained from collected blood samples and were analyzed for GADA and IAA using the immunoradiometric assay. Results: GADA was present in 16 out of 44 (36.3 %) patients,3 out of 52 (5.7 %) siblings and 0/16 (0.0 %) of the controls. While, IAA was positive in 28 out of 44 (63.6 %) patients, 6 out of 52 (11.5 %) siblings and 0/16 (0.0 %) controls. Statistical analysis: Differences between groups were assessed using Chi-square test. Statistical tests were performed using SPSS version 20 and P-value less than 0.05 was considered significant. Significantly high positivity of GADA in patients versus siblings and controls was noted (P<0.001). Conclusion: High positivity of IAA in patients versus siblings and controls was noted as well (P<0.01 and P<0.001, respectively). Saghir et al ____________________________________________________ ISSN-2347-5447 BBB[4][2][2016] 055-064 Introduction Diabetes mellitus (DM) is an important non-communicable disease. Universally, it is expected that 382 million people are suffering from diabetes with a prevalence of 8.3 %. It was reported that higher prevalence rates were estimated in North America and the Caribbean (11 %), followed by Middle East and North Africa (9.2 %) and Western Pacific regions (8.6 %). 2 Measurements of islet autoantibodies can aid the diagnosis of autoimmune diabetes and the discovery of such antibodies in non-diabetic individuals indicates a considerable increased risk for subsequent development of Type 1 Diabetes mellitus (T1DM). T1DM is an organspecific autoimmune disease that results in irreparable breakdown in insulin secretion. Hyperglycemia emerges when 80–90 % of the islet ß-cells disappear. T1DM is principally insulinopenic diabetes that can be sub-classified as autoimmune T1DM (type 1a) along with several associated autoantibodies or idiopathic T1DM (type1b). T1DM is strongly associated with both cellular and humoral immune responses to insulin producing beta cells. Individuals at risk can be identified on the basis of the positivity for islet autoantibodies. Therefore, diabetes risk is greater among people with more than one islet autoantibody or with higher titer of such antibodies. Human leukocyte antigens (HLA) genes are the main genetic factor that controls T1DM, and they appear capable of modulating the initiation and development of β-cell autoimmunity. The universal nature of antibodies in glutamic acid decarboxylase (GADA) and islet cell antibodies (ICA) was observed after the medical diagnosis of TID, in addition to highly variable concentrations for GADA. Studies in Caucasian populations have revealed an 80 % 90 % occurrence of autoantibodies in patients newly diagnosed with T1DM. Similarly, related studies from Asia have also established a 83 % 90 % occurrence of GADA in Japanese patients affected with T1DM. The mechanisms that determine the age-dependent effect of islet autoantigen specific autoantibodies are not fully comprehended. T1D is twice as prevalent among men younger than 20 years. However, this disparity between sexes is not easily elucidated by the diagnostic sensitivity of the autoantibodies. The notion that the diagnostic sensitivity differs with age and occasionally with sex has significant outcomes when using autoantibodies to predict T1D. Previous studies have shown a decline in prevalence for all autoantibodies with older age for both sexes. The diabetes duration-related decline in the levels and occurrence of autoantibodies were also observed. This study revealed a reduction in prevalence for all autoantibodies in both sexes affected by diabetes exceeding 7 years. An inverse correlation was confirmed between GADA, ICA and diabetes duration in patients with Type 1diabetes. The autoantibodies detected at the initiation of T1DM include: Islet cell autoantibodies (ICAs), initially described in the 1970s; IAA; 64-kDa autoantibodies (64KAs); insulin receptor auto-antibodies; carboxypeptidase-H auto-antibodies; heat shock protein (HSP) autoantibodies (identified in the 1980s), and GADA recognized in the 1990s. Afterwards, an array of different islet autoantibodies was identified comprising51-kDa aromatic-Lamino-acid decarboxylase auto-antibodies, chymotrypsinogen-related 30-kD pancreatic auto-antibodies, glima 38 auto-antibodies, tyrosine phosphatase-like protein autoantibodies (IA-2As) and others. The present study aims to determine the frequency of GADA and IAA in patients afflicted with T1DM along with their relations in Taiz, Yemen. Saghir et al ____________________________________________________ ISSN-2347-5447 BBB[4][2][2016] 055-064 Material and Methods Inclusion criteria For all evaluated groups, participants with good health and age more than 6 years were enrolled in this study. Exclusion criteria Non-healthy patients suffering from chronic diseases such as renal failure, heart diseases or hepatic diseases were excluded or volunteers with age less than 6 years. Study population Population consisted of three groups of Yemeni subjects from Taiz City. The patients group consisted of 44 T1DM patients, siblings group consisted of 52 unaffected siblings, while the non-diabetic controls group consisted of 16 individuals. This study was approved by ethics committee at Hodeidah University, Hodeidah, Yemen. Data and samples collection Data collected from patients with T1DM, their siblings and controls includes age, gender and duration of the disease. Blood samples were collected from the study population during the period June to December 2005 at AL-Thawrah Hospital, Taiz, Yemen. After obtaining the informed consent, about 5 mL of venous blood were drawn from T1DM patients, their siblings and control into plain tubes. Serum samples were separated within half an hour by centrifugation at 1500 g at room temperature for 5 min, the sera were then aliquoted and stored at –20 C until analyzed. Detection of IAA and GADA by immunoradiometricassay Measuring of IAA and GADA was done using commercial kits 125 I IRM assay (Beckman coulter company, France). Manufacturer’s instructions were followed in calculating and converting the results into arbitrary units by extrapolation from a standard curve. Positive results were considered when the antibody concentration exceeds 1.0 U/mL. Statistical analysis Differences between groups were assessed by Chi-square test. Statistical tests were performed using SPSS version 20 (SPSS Inc., Chicago, IL, USA). P-value less than 0.05 was considered significant.