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- Kockum, Ingrid, et al.
(författare)
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Genetic and immunological findings in patients with newly diagnosed insulin-dependent diabetes mellitus
- 1996
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Ingår i: Hormone and Metabolic Research. - : Georg Thieme Verlag KG. - 0018-5043 .- 1439-4286. ; 28:7, s. 344-347
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Tidskriftsartikel (refereegranskat)abstract
- Two large population-based case-control studies are reviewed. The aim is to determine the effects of HLA, other genetic factors and immune markers (ICA, IAA and GAD65Ab) on the age at onset of insulin-dependent diabetes mellitus (IDDM) in 0-34 year olds. The primary HLA risk gene sequence for IDDM was difficult to identify because of the low recombination frequency within the HLA region. The frequency of the DR3-DQA1 * 0501-DQB1 * 0201 haplotype and the DR3-DQA1 * 0501 DQB1 * 0201 (DQ2)/DR4-DQA1 * 0301-DQB1 * 0302 (DQ8) genotype were higher among patients diagnosed before the age of 10 compared with those diagnosed after the age of 30. The negatively associated haplotype, DR15-DQA1 * 0102-DQB1 * 0602 was absent before the age of 10, but the frequency increased with increasing age at onset. The IDDM2 gene representing the variable number of tandem repeat (VNTR) sequences and 5' of the insulin gene on chromosome 11 were associated with IDDM since homozygous short VNTR was positive but not homozygous, and heterozygous long VNTR was negatively associated with the disease. The diagnostic sensitivity and specificity of GAD65 (GA65Ab) and insulin (IAA) autoantibodies varied with the age at onset and gender. GAD65Ab had the highest sensitivity (> 80%) in patients older than 20 years of age with no difference in gender. The lowest sensitivity (54%) was in 0-10 year old boys, while age did not affect the sensitivity in girls. In contrast, the sensitivity of IAA was highest (46%) before the age of 15 but decreased thereafter as did the sensitivity for ICA. Classification of patients who develop IDDM above 20-25 years of age was inadequate since many patients classified with NIDDM either had GAD65Ab or ICA or developed these antibodies after 1-2 years of NIDDM. We conclude that not only age but also gender affects the risk for IDDM associated with HLA, other IDDM genes as well as commonly used immunological markers for IDDM.
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- Törn, C., et al.
(författare)
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Prognostic factors for the course of beta cell function in autoimmune diabetes
- 2000
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 85:12, s. 4619-4623
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Tidskriftsartikel (refereegranskat)abstract
- This study presents a 2-yr follow-up of 281 patients, aged 15-34 yr, diagnosed with diabetes between 1992 and 1993. At diagnosis, 224 (80%) patients were positive for at least one of the following autoantibodies: islet cell antibodies (ICAs), glutamic acid decarboxylase antibodies (GADAs), or tyrosine phosphatase antibodies (IA-2As), the remaining 57 (20%) patients were negative for all three autoantibodies. At diagnosis, C-peptide levels were lower (0.27, 0.16-0.40 nmol/L) in autoantibody-positive patients compared with autoantibody-negative patients (0.51, 0.28-0.78 nmol/L, P < 0.001). After 2 yr, C-peptide levels had decreased significantly in patients with autoimmune diabetes (0.20, 0.10-0.37 nmol/L, P = 0.0018), but not in autoantibody-negative patients. In patients with autoimmune diabetes, a low initial level of C-peptide (odds ratio, 2.6, 95% confidence interval, 1.7-4.0) and a high level of GADAs (odds ratio, 2.5, 95% confidence interval, 1.1-5.7) were risk factors for a C-peptide level below the reference level of 0.25 nmol/L 2 yr after diagnosis. Body mass index had a significant effect in the multivariate analysis only when initial C-peptide was not considered. Factors such as age, gender, levels of ICA or IA-2A or insulin autoantibodies (analyzed in a subset of 180 patients) had no effect on the decrease in ▀-cell function. It is concluded that the absence of pancreatic islet autoantibodies at diagnosis were highly predictive for a maintained ▀-cell function during the 2 yr after diagnosis, whereas high levels of GADA indicated a course of decreased ▀-cell function with low levels of C-peptide. In autoimmune diabetes, an initial low level of C-peptide was a strong risk factor for a decrease in ▀-cell function and conversely high C-peptide levels were protective. Other factors such as age, gender, body mass index, levels of ICA, IA-2A or IAA had no prognostic importance.
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