Homozygosity of the polymorphism MICA5.1 identifies extreme risk of progression to overt adrenal insufficiency among 21-hydroxylase antibody-positive patients with type 1 diabetes

CONTEXT

Autoimmunity associated with Addison's disease (AD) can be detected by measuring 21-hydroxylase (21OH) autoantibodies. Subjects with type 1 diabetes (T1D) are at increased risk for AD. Genetic factors including HLA-DRB1*0404 and MICA have been associated with AD in populations with and without T1D.

OBJECTIVE

The objective of the study was to examine the effect of the MICA5.1 allele in subjects with 21OH autoantibodies on progression to AD.

DESIGN

Two components were used: 1) a cross-sectional study with subjects with AD identified and enrolled from September 1993 to November 2008 and 2) a cohort study prospectively following up patients with T1D who screened positive for 21OH autoantibodies.

SETTING

Subjects were identified from the Barbara Davis Center and through the National Adrenal Diseases Foundation.

PATIENTS

Sixty-three subjects with AD were referred through the National Adrenal Diseases Foundation (AD referrals). Sixty-three subjects with positive 21OH antibodies from the Barbara Davis Center were followed up for progression to AD, and 11 were diagnosed with AD (progressors).

RESULTS

Seventy-three percent of progressors (eight of 11) and 57% of AD referrals (36 of 63) were MICA5.1 homozygous (P = ns). Overall, 59% of patients with AD (44 of 74) were MICA5.1/5.1 compared with 17% of nonprogressors (nine of 52) (P < 0.0001) and 19% of normal DR3/4-DQB1*0302 controls (64 of 336) (P < 0.0001).

CONCLUSIONS

Identifying extreme risk should facilitate monitoring of progression from 21OH antibody positivity to overt AD. The HLA-DR3/0404 genotype defines high-risk subjects for adrenal autoimmunity. MICA5.1/5.1 may define those at highest risk for progression to overt AD, a feature unique to AD and distinct from T1D.

Do non-HLA genes influence development of persistent islet autoimmunity and type 1 diabetes in children with high-risk HLA-DR,DQ genotypes?

OBJECTIVE

Specific alleles of non-HLA genes INS, CTLA-4, and PTPN22 have been associated with type 1 diabetes. We examined whether some of these alleles influence development of islet autoimmunity or progression from persistent islet autoimmunity to type 1 diabetes in children with high-risk HLA-DR,DQ genotypes.

RESEARCH DESIGN AND METHODS

Since 1993, the Diabetes Autoimmunity Study in the Young (DAISY) has followed 2,449 young children carrying HLA-DR,DQ genotypes associated with type 1 diabetes. Of those, 112 have developed islet autoimmunity (persistent autoantibodies to insulin, GAD65, and/or IA-2), and 47 of these have progressed to type 1 diabetes. The influence of polymorphisms of INS(-23Hph1), CTLA-4(T17A), and PTPN22(R620W) on development of persistent islet autoimmunity and progression to type 1 diabetes was evaluated by parametric models and by survival analyses.

RESULTS

PTPN22(R620W) allele T was associated with development of persistent islet autoimmunity (hazard ratio 1.83 [95% CI 1.27-2.63]) controlling for ethnicity, presence of HLA-DR3/4,DQB1*0302, and having a first-degree relative with type 1 diabetes. Survival analyses showed a significantly (P = 0.002) higher risk of persistent islet autoimmunity by age 10 years for the TT genotype (27.3%) than for the CT or CC genotype (7.9 and 5.3%, respectively). Cumulative risk of persistent islet autoimmunity was slightly higher (P = 0.02) for the INS(-23Hph1) AA genotype (7.8%) than for the AT or TT genotype (4.2 and 6.4% risk by age 10 years, respectively).

CONCLUSIONS

Whereas the HLA-DR3/4,DQB1*0302 genotype had a dramatic influence on both development of islet autoimmunity and progression to type 1 diabetes, the PTPN22(R620W) T allele significantly influences progression to persistent islet autoimmunity in the DAISY cohort.

A report on the International Transglutaminase Autoantibody Workshop for Celiac Disease

OBJECTIVES

Measurement of transglutaminase autoantibodies (TGAA) is considered to be the most efficient single serologic test for celiac disease (CD) by the American Gastroenterological Association Institute. We hypothesized that a large international collaborative effort toward improving and standardizing TGAA measurement is both feasible and necessary. The primary aim of this workshop is to compare TGAA assays among various research and clinical laboratories to examine assay concordance and improve (and eventually standardize) the TGAA assay.

METHODS

A total of 20 laboratories (5 commercial laboratories, 15 research and clinical laboratories) participated that included enzyme-linked immunosorbent assay (ELISA) and radiobinding assays. A total of 150 serum samples were distributed to each laboratory, with each laboratory receiving an equal aliquot that was coded and blinded, composed of 100 healthy control sera and 50 CD sera.

RESULTS

Laboratory sensitivity ranged from 69% to 93% and specificity ranged from 96% to 100%. By receiver operator characteristic analysis, the area under the curve (C index) ranged from 0.9488 to 0.9904. When analyzing for linear correlation, r-squared was as high as 0.8882 but as low as 0.4244 for the celiac samples between different laboratories performing ELISA.

CONCLUSIONS

This transglutaminase autoantibody workshop allows for larger-scale international participation for the purposes of improving and eventually standardizing the TGAA assay with subsequent workshops.

Two single nucleotide polymorphisms identify the highest-risk diabetes HLA genotype: potential for rapid screening

OBJECTIVE

People with the HLA genotype DRB1*0301-DQA1*0501-DQB1*0201/DRB1*04-DQA1*0301-DQB1*0302 (DR3/4-DQ8) are at the highest risk of developing type 1 diabetes. We sought to find an inexpensive, rapid test to identify DR3/4-DQ8 subjects using two single nucleotide polymorphisms (SNPs).

RESEARCH DESIGN AND METHODS

SNPs rs2040410 and rs7454108 were associated with DR3-DQB1*0201 and DR4-DQB1*0302. We correlated these SNPs with HLA genotypes and with publicly available data on 5,019 subjects from the Type 1 Diabetes Genetic Consortium (T1DGC). Additionally, we analyzed these SNPs in samples from 143 HLA-typed children who participated in the Diabetes Autoimmunity Study of the Young (DAISY) using Taqman probes (rs7454108) and restriction digest analysis (rs2040410).

RESULTS

With a simple combinatorial rule, the SNPs of interest identified the presence or absence of the DR3/4-DQ8 genotype. A wide variety of genotypes were tested for both SNPs. In T1DGC samples, the two SNPs were 98.5% (1,173 of 1,191) sensitive and 99.7% (3,815 of 3,828) specific for DR3/4-DQ8. In the DAISY population, the test was 100% (69 of 69) sensitive and 100% (74 of 74) specific. Overall, the sensitivity and specificity for the test were 98.57 and 99.67%, respectively.

CONCLUSIONS

A two-SNP screening test can identify the highest risk heterozygous genotype for type 1 diabetes in a time- and cost-effective manner.

Analysis of single nucleotide polymorphisms identifies major type 1A diabetes locus telomeric of the major histocompatibility complex

OBJECTIVE

HLA-DRB1*03-DQB1*0201/DRB1*04-DQB1*0302 (DR3/4-DQ8) siblings who share both major histocompatibility complex (MHC) haplotypes identical-by-descent with their proband siblings have a higher risk for type 1A diabetes than DR3/4-DQ8 siblings who do not share both MHC haplotypes identical-by-descent. Our goal was to search for non-DR/DQ MHC genetic determinants that cause the additional risk in the DR3/4-DQ8 siblings who share both MHC haplotypes.

RESEARCH DESIGN AND METHODS

We completed an extensive single nucleotide polymorphism (SNP) analysis of the extended MHC in 237 families with type 1A diabetes from the U.S. and 1,240 families from the Type 1 Diabetes Genetics Consortium.

RESULTS

We found evidence for an association with type 1A diabetes (rs1233478, P = 1.6 x 10(-23), allelic odds ratio 2.0) in the UBD/MAS1L region, telomeric of the classic MHC. We also observed over 99% conservation for up to 9 million nucleotides between chromosomes containing a common haplotype with the HLA-DRB1*03, HLA-B*08, and HLA-A*01 alleles, termed the "8.1 haplotype." The diabetes association in the UBD/MAS1L region remained significant both after chromosomes with the 8.1 haplotype were removed (rs1233478, P = 1.4 x 10(-12)) and after adjustment for known HLA risk factors HLA-DRB1, HLA-DQB1, HLA-B, and HLA-A (P = 0.01).

CONCLUSIONS

Polymorphisms in the region of the UBD/MAS1L genes are associated with type 1A diabetes independent of HLA class II and I alleles.

Natural history of antibodies to deamidated gliadin peptides and transglutaminase in early childhood celiac disease

INTRODUCTION

Gliadin proteins play a key role in the pathogenesis of celiac disease; however, as a screen for celiac disease, anti-gliadin antibody testing has been replaced by the more sensitive and specific serological assays for transglutaminase autoantibodies (TGAA). A new generation of anti-gliadin antibody assays has been developed to detect synthetic, deamidated homologous gliadin peptides (DGP) with high sensitivity and specificity.

METHODS

Sera were collected prospectively from children with an increased risk for celiac disease as part of an ongoing study at Denver, and studied for the development of celiac autoimmunity. We investigated the high-performance DGP antibody assay in 50 TGAA-positive children both before the development of celiac autoimmunity and following the institution of a gluten-free diet to determine the relationship of DGP antibodies to TGAA. TGAA were measured by an in-house radioassay.

RESULTS

DGP antibodies and TGAA parallel each other over the period of years children were studied. DGP antibodies resolved sooner than TGAA in subjects on a gluten-free diet. DGP antibodies appeared earlier than TGAA in 9 children.

CONCLUSIONS

Measuring DGP antibodies may be more useful than TGAA in monitoring children on a gluten-free diet. DGP antibodies can precede the appearance of TGAA in some at-risk children.

HLA-DPB1*0402 protects against type 1A diabetes autoimmunity in the highest risk DR3-DQB1*0201/DR4-DQB1*0302 DAISY population

OBJECTIVE

A major goal in genetic studies of type 1A diabetes is prediction of anti-islet autoimmunity and subsequent diabetes in the general population, as >85% of patients do not have a first-degree relative with type 1A diabetes. Given prior association studies, we hypothesized that the strongest candidates for enhancing diabetes risk among DR3-DQB1*0201/DR4-DQB1*0302 individuals would be alleles of DP and DRB1*04 subtypes and, in particular, the absence of reportedly protective alleles DPB1*0402 and/or DRB1*0403.

RESEARCH DESIGN AND METHODS

We genotyped 457 DR3-DQB1*0201/DR4-DQB1*0302 Diabetes Autoimmunity Study of the Young (DAISY) children (358 general population and 99 siblings/offspring of type 1 diabetic patients) at the DPB1, DQB1, and DRB1 loci using linear arrays of immobilized sequence-specific oligonucleotides, with direct sequencing to differentiate DRB1*04 subtypes.

RESULTS

By survival curve analysis of DAISY children, the risk of persistently expressing anti-islet autoantibodies is approximately 55% for relatives (children with a parent or sibling with type 1 diabetes) in the absence of these two protective alleles vs. 0% (P = 0.02) with either protective allele, and the risk is 20 vs. 2% (P = 0.004) for general population children. Even when the population analyzed is limited to DR3-DQB1*0201/DR4-DQB1*0302 children with DRB1*0401 (the most common DRB1*04 subtype), DPB1*0402 influences development of anti-islet autoantibodies.

CONCLUSIONS

The ability to identify a major group of general population newborns with a 20% risk of anti-islet autoimmunity should enhance both studies of the environmental determinants of type 1A diabetes and the design of trials for the primary prevention of anti-islet autoimmunity.

Plasma micronutrients are associated with dietary intake and environmental tobacco smoke exposure in a paediatric population

BACKGROUND

While adult populations have been well described in terms of nutritional status, such as the concentration of nutrient biomarkers, little work has been done in healthy paediatric populations.

OBJECTIVE

The primary objective of this analysis was to explore the determinants of plasma micronutrients in a group of healthy infants and children.

DESIGN

The Diabetes Autoimmunity Study in the Young (DAISY) has enrolled 1433 newborns at increased risk for type 1 diabetes in Denver, Colorado. A representative random sample of 257 children from the DAISY cohort between the ages of 9 months and 8 years with a total of 815 clinic visits over time was used in this analysis. Annual dietary intake was assessed over time with Willett food-frequency questionnaires that were validated in this population. Environmental tobacco smoke (ETS) was assessed using a validated survey. Plasma samples were tested for vitamins, carotenoids and total lipids. Predictors of plasma micronutrients were evaluated using mixed models for longitudinal data, while adjusting for age, human leukocyte antigen genotype, type 1 diabetes family history and other potential confounders and covariates.

RESULTS

Increased micronutrient intake was associated with increased levels of their respective plasma nutrient, with the exception of gamma-tocopherol. Independent of dietary intake, levels of alpha- and beta-carotene and beta-cryptoxanthin were significantly lower, and gamma-tocopherol was significantly higher, in children who were exposed to ETS.

CONCLUSION

Dietary intake predicts plasma micronutrient levels. Exposure to ETS potentially could have negative health effects in this young population.

Association of the PTPN22/LYP gene with type 1 diabetes

OBJECTIVES

The goal of this study was to verify the association between type 1 diabetes (T1D) and the protein tyrosine phosphatase, non-receptor type 22 (PTPN22) gene in non-Hispanic whites (NHWs) and Hispanics from Colorado.

SUBJECTS AND METHODS

The C1858T single-nucleotide polymorphism within the PTPN22 gene was genotyped in 753 patients with T1D ascertained from the diabetes clinic at the Barbara Davis Center in Denver and 662 control population.

RESULTS

Both the PTPN22 CT genotype [odds ratio (OR) = 1.96; p < 0.0001] and TT genotype (OR = 4.41; p = 0.02) were significantly associated with T1D in the NHW population. While the association was stronger in subjects with non-HLA-DR3/4 genotypes than in those with the HLA-DR3/4 genotype, regression analyses did not reveal significant interaction between PTPN22 genotypes and HLA-DR3/4. The strength of the association was similar in males and females, patients diagnosed before and after age 10 yr, and in Hispanics and NHWs.

CONCLUSION

In this study, we confirm that PTPN22 is associated with T1D in the Colorado population.

TEDDY--The Environmental Determinants of Diabetes in the Young: an observational clinical trial

The aim of the TEDDY study is to identify infectious agents, dietary factors, or other environmental agents, including psychosocial factors, which may either trigger islet autoimmunity, type 1 diabetes mellitus (T1DM), or both. The study has two end points: (a) appearance of islet autoantibodies and (b) clinical diagnosis of T1DM. Six clinical centers screen newborns for high-risk HLA genotypes. As of December 2005 a total of 54,470 newborns have been screened. High-risk HLA genotypes among 53,560 general population (GP) infants were 2576 (4.8%) and among 910 newborns with a first-degree relative (FDR) were 194 (21%). A total of 1061 children have been enrolled. The initial enrollment results demonstrate the feasibility of this complex and demanding a prospective study.

Extreme genetic risk for type 1A diabetes

Type 1A diabetes (T1D) is an autoimmune disorder the risk of which is increased by specific HLA DR/DQ alleles [e.g., DRB1*03-DQB1*0201 (DR3) or DRB1*04-DQB1*0302 (DR4)]. The genotype associated with the highest risk for T1D is the DR3/4-DQ8 (DQ8 is DQA1*0301, DQB1*0302) heterozygous genotype. We determined HLA-DR and -DQ genotypes at birth and analyzed DR3/4-DQ8 siblings of patients with T1D for identical-by-descent HLA haplotype sharing (the number of haplotypes inherited in common between siblings). The children were clinically followed with prospective measurement of anti-islet autoimmunity and for progression to T1D. Risk for islet autoimmunity dramatically increased in DR3/4-DQ8 siblings who shared both HLA haplotypes with their diabetic proband sibling (63% by age 7, and 85% by age 15) compared with siblings who did not share both HLA haplotypes with their diabetic proband sibling (20% by age 15, P < 0.01). 55% sharing both HLA haplotypes developed diabetes by age 12 versus 5% sharing zero or one haplotype (P = 0.03). Despite sharing both HLA haplotypes with their proband, siblings without the HLA DR3/4-DQ8 genotype had only a 25% risk for T1D by age 12. The risk for T1D in the DR3/4-DQ8 siblings sharing both HLA haplotypes with their proband is remarkable for a complex genetic disorder and provides evidence that T1D is inherited with HLA-DR/DQ alleles and additional MHC-linked genes both determining major risk. A subset of siblings at extremely high risk for T1D can now be identified at birth for trials to prevent islet autoimmunity.

Multi-SNP analysis of MHC region: remarkable conservation of HLA-A1-B8-DR3 haplotype

Technology has become available to cost-effectively analyze thousands of single nucleotide polymorphisms (SNPs). We recently confirmed by genotyping a small series of class I alleles and microsatellite markers that the extended haplotype HLA-A1-B8-DR3 (8.1 AH) at the major histocompatibility complex (MHC) is a common and conserved haplotype. To further evaluate the region of conservation of the DR3 haplotypes, we genotyped 31 8.1 AHs and 29 other DR3 haplotypes with a panel of 656 SNPs spanning 4.8 Mb in the MHC region. This multi-SNP evaluation revealed a 2.9-Mb region that was essentially invariable for all 31 8.1 AHs. The 31 8.1 AHs were >99.9% identical for 384 consecutive SNPs of the 656 SNPs analyzed. Future association studies of MHC-linked susceptibility to type 1 diabetes will need to account for the extensive conservation of the 8.1 AH, since individuals who carry this haplotype provide no information about the differential effects of the alleles that are present on this haplotype.

Genetic prediction of autoimmunity: initial oligogenic prediction of anti-islet autoimmunity amongst DR3/DR4-DQ8 relatives of patients with type 1A diabetes

In this study, the combined risk for expressing anti-islet autoantibodies and type 1A diabetes (T1D) was prospectively examined in 85 sampled relatives who had the high-risk HLA genotype (DR3-DQ8 DR4-DQ2). An insulin gene polymorphism, -23 HphI, and a lymphocyte tyrosine phosphatase gene polymorphism at position 1858C>T (amino acid 620 Arg to Trp), PTPN22/LYP, were analyzed. Life tables were created evaluating time to anti-islet autoantibody development and T1D. Of relatives with the high-risk HLA type followed for 3years, 9 of 43 (28.1%) with the high-risk -23 HphI polymorphism developed anti-islet autoantibodies versus two of 36 (5.6%) relatives with the lower-risk -23 HphI genotypes (p=0.048). Of relatives with the high-risk HLA type followed for 5years, eight of 32 (25.0%) with the high-risk -23 HphI polymorphism (A/A) developed T1D versus zero of 26 (0%) relatives with the lower-risk -23 HphI genotypes (A/T and T/T) (p=0.006). The PTPN22/LYP polymorphism, with genotypes C/C, C/T, and T/T, did not show a significant difference in risk by genotype. These results highlight the multiplicative risk of combined high-risk genotypes at different loci in terms of time to autoantibody and autoimmune disease development.

Association of non-HLA genes with type 1 diabetes autoimmunity

Approximately 50% of the genetic risk for type 1 diabetes is attributable to the HLA region. We evaluated associations between candidate genes outside the HLA region-INS, cytotoxic T-lymphocyte-associated antigen (CTLA)-4, interleukin (IL)-4, IL-4R, and IL-13 and islet autoimmunity among children participating in the Diabetes Autoimmunity Study in the Young (DAISY). Children with persistent islet autoantibody positivity (n = 102, 38 of whom have already developed diabetes) and control subjects (n = 198) were genotyped for single nucleotide polymorphisms (SNPs) in the candidate genes. The INS-23Hph1 polymorphism was significantly associated with both type 1 diabetes (OR = 0.30; 95% CI 0.13-0.69) and persistent islet autoimmunity but in the latter, only in children with the HLA-DR3/4 genotype (0.40; 0.18-0.89). CTLA-4 promoter SNP was significantly associated with type 1 diabetes (3.52; 1.22-10.17) but not with persistent islet autoimmunity. Several SNPs in the IL-4 regulatory pathway appeared to have a predisposing effect for type 1 diabetes. Associations were found between both IL-4R haplotypes and IL-4-IL-13 haplotypes and persistent islet autoimmunity and type 1 diabetes. This study confirms the association between the INS and CTLA-4 loci and type 1 diabetes. Genes involved in the IL-4 regulatory pathway (IL-4, IL-4R, IL-13) may confer susceptibility or protection to type 1 diabetes depending on individual SNPs or specific haplotypes.

Need for quantitative assessment of transglutaminase autoantibodies for celiac disease in screening-identified children

OBJECTIVES

To assess several transglutaminase autoantibody (TGAA) assays in their ability to distinguish celiac disease (CD) in screening-identified children with abnormal intestine biopsy specimens from those with normal biopsy specimens.

STUDY DESIGN

Children at risk for CD (n = 54) composed of type 1 diabetics, first-degree relatives of type 1 diabetics or CD, and HLA-DQ2+ individuals followed from birth received intestine biopsy. Sera obtained at the time of biopsy were tested for TGAA, using the radioimmunoassay and 5 other commercially available enzyme-linked immunosorbent assays.

RESULTS

False-positive rates ranged from 28% to 80%. The positive predictive value (PPV) of the tests ranged from 63% to 84% (lower than reported for symptomatic children). Setting a higher cutoff for each assay maximized PPV.

CONCLUSIONS

There are significant quantitative differences among all TGAA assays that could affect interpretation of a positive test for CD. The overall false-positive rate for all assays was high in this population. Using the assay as a quantitative rather than qualitative tool by increasing the cutoff of positivity to indicate biopsy increases PPV. Multicenter workshops are needed to identify critical differences and to standardize TGAA assays among laboratories.

Hypertension prevalence, awareness, treatment, and control in an adult type 1 diabetes population and a comparable general population

OBJECTIVE

To compare the prevalence, awareness, treatment, and control of hypertension in a population-representative sample of adults with type 1 diabetes and comparable nondiabetic control subjects.

RESEARCH DESIGN AND METHODS

In 2000-2002, the Coronary Artery Calcification in Type 1 Diabetes Study enrolled 1,416 individuals aged 19-56 years with no known history of coronary artery disease: 652 type 1 diabetic patients (46% male, mean age 37 years) and 764 nondiabetic control subjects (50% male, mean age 39 years). Subjects were asked if they had been told by a physician that they had hypertension or were on a blood pressure medication. Blood pressure was measured using standardized Joint National Committee (JNC) protocol.

RESULTS

Type 1 diabetic subjects, compared with nondiabetic subjects, had higher rates of hypertension prevalence (43 vs. 15%, P < 0.001), awareness (53 vs. 45%, P = 0.11), treatment (87 vs. 47%, P < 0.001), and control (55 vs. 32%, P < 0.001) for the JNC 6 goal (130/85 mmHg). Only 42% of all type 1 diabetic hypertensive subjects met the new JNC 7 goal (130/80 mmHg). Type 1 diabetic subjects had better blood pressure control (72 vs. 32%, P < 0.0001), using 140/90 mmHg as a common measure. The majority of treated subjects were on a single antihypertensive agent (75 vs. 64%).

CONCLUSIONS

Subjects with type 1 diabetes have higher rates of hypertension prevalence, treatment, and control than nondiabetic subjects. However, hypertension remains largely uncontrolled, even if treated in high-risk populations, such as type 1 diabetic subjects and undiagnosed individuals in the general population. Achieving more stringent blood pressure goals will require increased attention and may necessitate the use of multiple antihypertensive agents.

Secondary attack rate of type 1 diabetes in Colorado families

OBJECTIVE

Families of children diagnosed with type 1 diabetes require counseling concerning type 1 diabetes risk in nondiabetic siblings and parents. No U.S. population-specific life-table risk estimates are currently available for parents, and those for siblings (2-6% by age 20 years) are based on family studies completed before 1987.

RESEARCH DESIGN AND METHODS

We analyzed family histories of 1,586 patients in Colorado with type 1 diabetes (83% non-Hispanic white, 10% Hispanic, and 7% other) diagnosed before 16 years of age and interviewed during 1999-2002. Families of probands with type 2, undetermined, or secondary diabetes (n = 53) or those with incomplete data (n = 137) were excluded. The median age at onset of the proband was 7.1 years and the median diabetes duration 3.5 years. Cumulative risk estimates were calculated using survival analysis for 2,081 full siblings and 3,016 biological parents.

RESULTS

In siblings, the overall risk of type 1 diabetes by age 20 years was 4.4%, but it was significantly (P < 0.0001) higher in siblings of probands diagnosed under age 7 years than in those diagnosed later. In parents, the overall risk by age 40 years was 2.6% and higher in fathers (3.6%) than in mothers (1.7%) of probands (P < 0.001). Similar to siblings, the risk was also higher (P = 0.006) in parents of probands diagnosed <7 years of age than in those diagnosed later.

CONCLUSIONS

Current risks of type 1 diabetes in Colorado siblings and parents of type 1 diabetic probands are higher than in the 1982 Pittsburgh study but similar to contemporary European rates. Recurrence risk of type 1 diabetes is significantly higher in first-degree relatives of probands diagnosed at a young age.

Urinary F2-isoprostanes in young healthy children at risk for type 1 diabetes mellitus

Oxidative stress has been linked to many diseases, but little information exists on biomarkers of oxidative stress in healthy children. The purpose of this study was to describe factors that correlate with urinary F2-isoprostanes, an indicator of oxidative stress, and to establish normal concentrations of F2-isoprostanes in children at risk to develop type 1 diabetes mellitus. Creatinine-adjusted urinary F2-isoprostanes were assessed in 342 Denver children under the age of 7 years, from whom we had collected data during 769 clinic visits from August 1997 through January 2001 (mean 2.3 visits per child). Children were identified by newborn screening for HLA-markers, of varying degrees of prediction, for the development of type 1 diabetes. Plasma antioxidants and carotenoids, age at clinic visit, vitamin supplement use, exposure to environmental tobacco smoke, gender, and race were evaluated as correlates to the degree of oxidative stress, using mixed models for longitudinal data. F2-isoprostane levels were highest in infancy and decreased nonlinearly until 7 years. Female gender, HLA-DR3/4 genotype, higher plasma gamma-tocopherol:total lipids ratio, and lower alpha-carotene:total lipids ratio correlated with higher F2-isoprostane levels. Normal values in this healthy population can be used as the basis for future studies of disease mechanisms involving oxidative stress.

Fluctuating transglutaminase autoantibodies are related to histologic features of celiac disease

BACKGROUND & AIMS

Asymptomatic children at risk for celiac disease (CD) and seropositive for immunoglobulin A anti-TG autoantibodies (TGAA) may lack small intestinal mucosal changes characteristic of CD. We have followed a group of children with serial testing for TGAA.

METHODS

Subjects were a group of at-risk children comprised of infants expressing HLA-DR3 on newborn screening, those with type 1A diabetes, or a first-degree relative of someone with type 1 diabetes. All children participating in the prospective study for development of CD underwent serial testing for TGAA. Data from clinical evaluation and small intestinal biopsy were compared to the TGAA levels followed over time.

RESULTS

In 42 children, serial TGAA determinations while on a gluten-containing diet showed levels fluctuating 10-100-fold over 3-12 months. A TGAA index more than 0.5 had a positive predictive value (PPV) for histologic confirmation of CD of 96% (22/23). A TGAA index above the usual cutoff for positivity (0.05) had a PPV of only 76% (28/37).

CONCLUSIONS

In children with TGAA seropositivity, the TGAA level varied over time and a higher titer predicted an abnormal biopsy characteristic of CD. A threshold for biopsy for diagnosis of CD could be set higher for screening-identified cases than for clinically identified cases to decrease the frequency of performing "normal" biopsies.

Differences in LDL oxidizability by glycemic status: the insulin resistance atherosclerosis study

OBJECTIVE

To investigate differences in LDL oxidizability by glycemic status within the Insulin Resistance Atherosclerosis Study cohort.

RESEARCH DESIGN AND METHODS

LDL oxidizability (lag time and oxidation rate) after exposure to copper was compared among 352 subjects with normal glucose tolerance (NGT), impaired glucose tolerance (IGT), newly diagnosed type 2 diabetes, and known type 2 diabetes.

RESULTS

After adjustment for age, clinic, ethnicity, sex, and smoking status, LDL oxidation rates differed by glycemic status (P = 0.001), with a strong trend (P = 0.0001) for reduced LDL oxidation rate with increasing extent and duration of glucose intolerance (2,378 +/- 54, 2,208 +/- 65, 2,145 +/- 71, and 2,115 +/- 48 arbitrary units [mean +/- SE] for NGT, IGT, newly diagnosed type 2 diabetes, and known type 2 diabetes, respectively). Differences in LDL oxidation rate among groups were relatively unaltered by adjustment for lipids and lipoproteins, hypertension, BMI, and waist-to-hip ratio (WHR) and remained significant even after further adjustment for dietary antioxidants and fatty acids, as well as medications. LDL lag times differed marginally by glycemic status (P = 0.058), with similar values for NGT, IGT, and newly diagnosed type 2 diabetes (57-60 min) but higher values for known type 2 diabetes (65 +/- 2). These differences were eliminated by further adjustment for lipids and lipoproteins, hypertension, BMI, and WHR.

CONCLUSIONS

We found that glycemic status influenced LDL oxidizability, with a paradoxical reduction in LDL oxidizability, as indicated by a lower LDL oxidation rate with increased extent and duration of glucose intolerance. This difference was only slightly attenuated by adjustment for relevant demographic, metabolic, dietary, and pharmacological factors that potentially influence LDL oxidation.

Cardiovascular disease mortality in Hispanics and non-Hispanic whites

Despite a worse cardiovascular disease (CVD) risk profile, Hispanics have lower CVD mortality than non-Hispanic Whites in studies based on death certificates. This study examined 310 deaths that occurred between 1984 and 1998 among 1,862 Hispanic and non-Hispanic White participants in the San Luis Valley Diabetes Study, using medical records to classify cause of death. Among persons without diabetes, the age-adjusted all-cause mortality rate was 6.1/1,000 person-years in non-Hispanic Whites and 7.4/1,000 person-years in Hispanics. Among persons with diabetes, it was 24.3/1,000 person-years in non-Hispanic Whites and 21.9/1,000 person-years in Hispanics. Among nondiabetics, the age-adjusted CVD mortality rate was 2.5/1,000 person-years in non-Hispanic Whites and 1.6/1,000 person-years in Hispanics. Among diabetics, it was 12.9/1,000 person-years in non-Hispanic Whites and 8.8/1,000 person-years in Hispanics. Among nondiabetics, the adjusted hazard ratio for CVD death in Hispanics compared with non-Hispanic Whites was 0.65 (95% confidence interval (CI): 0.34, 1.23). The hazard ratio for coronary heart disease death was 0.95 (95% CI: 0.35, 2.59). Among diabetics, the hazard ratio for CVD death, after adjustment for conventional and diabetes risk factors, was 0.44 (95% CI: 0.26, 0.74), and for coronary heart disease death it was 0.43 (95% CI: 0.21, 0.91). A statistically significant decreased risk of CVD death was observed only in male Hispanics with diabetes. Competing mortality or factors that interact with diabetes may explain these differences.

Universal versus targeted screening of infants for sickle cell disease: a cost-effectiveness analysis

OBJECTIVE

To compare the health outcomes, costs, and incremental cost-effectiveness of universal neonatal screening for sickle cell disease (SCD) with screening targeted to African Americans.

STUDY DESIGN

A cost-effectiveness analysis was done by using a Markov simulation model that considered the costs and outcomes associated with the prevention and treatment of sepsis in those with sickle cell anemia and sickle beta(0)-thalassemia. Three strategies were compared: (1) no screening, (2) targeted screening of African Americans, and (3) universal screening for SCD.

RESULTS

In the base case analysis, targeted screening of African Americans compared with no screening cost $6709 per additional year of life saved, and universal screening compared with targeted screening cost $30,760 per additional year of life saved. In a sensitivity analysis, the cost per additional year of life saved with universal screening compared with targeted screening was positively correlated with the delivery rate of targeted screening and was inversely related to the proportion of African Americans in the population.

CONCLUSIONS

Targeted screening of African American newborns for SCD compared with no screening is always cost-effective. Universal screening compared with targeted screening always identifies more infants with disease, prevents more deaths, and is cost-effective given certain delivery rates for targeted screening and proportions of African Americans in the population.

DRB1*04 and DQ alleles: expression of 21-hydroxylase autoantibodies and risk of progression to Addison's disease

Of 957 patients with type 1 diabetes without known Addison's disease 1.6% (n = 15) were positive for 21-hydroxylase autoantibodies. Among DQ8/DQ2 heterozygous patients, the percentage expressing 21-hydroxylase autoantibodies was 5% (10 of 208) vs. less than 0.5% of patients with neither DQ8 nor DQ2. Three of the diabetic patients found to have 21-hydroxylase autoantibodies on screening were subsequently diagnosed with Addison's disease. Overall, the genotype DQ8/DQ2, consisting of DRB1*0404/DQ8 with DRB1*0301/DQ2, was present in 14 of 21 patients with Addison's disease (8 of 12 with diabetes and 6 of 9 without diabetes or antiislet autoantibodies) vs. 0.7% of the general population (109 of 15,547; P < 10(-6)) and 11% of patients with DM without Addison's disease (62 of 578; P < 10(-6)). Among patients with diabetes with DQ8, Addison's disease was strongly associated with the specific DRB1 subtype, DRB1*0404 (8 of 9 patients from 8 families, in contrast to only 109 of 408 DQ8 DM patients with diabetes without Addison's disease having DRB1*0404; P < 0.001). Among 21-hydroxylase autoantibody-positive DQ8 patients, 80% with DRB1*0404 (12 of 15) had Addison's disease, in contrast to 1 of 10 autoantibody-positive patients with DRB1*0401 or DRB1*0402 (P < 0.001). We conclude that patients with DRB1*0404 and 21-hydroxylase autoantibodies are at high risk for Addison's disease. Patients with DRB1*0401 and DRB1*0402 have more limited progression to Addison's disease despite the presence of 21-hydroxylase autoantibodies.

Definition of multiple ICA512/phogrin autoantibody epitopes and detection of intramolecular epitope spreading in relatives of patients with type 1 diabetes

The related tyrosine phosphatase-like proteins, islet cell antigen 512 (ICA512) and phosphatase homologue in granules of insulinoma (phogrin), are major targets of autoantibodies in patients with type 1 diabetes. In the current study, we have examined the overlapping specificities and antigenic epitopes of autoantibodies to ICA512 and phogrin and determined whether intramolecular epitope spreading occurs during the development of diabetic autoimmunity. ICA512 autoantibodies and phogrin autoantibodies were detected in 65-70% (n = 110) of patients with new-onset type 1 diabetes and 60-65% (n = 42) of prediabetic relatives of patients with type 1 diabetes. Of the sera, 10% reacted with ICA512 but not phogrin, whereas only 1% of sera reacted with phogrin but not ICA512. The binding of phogrin autoantibodies in 88 dual (ICA512 and phogrin) autoantibody-positive sera could be completely blocked by excess recombinant ICA512, whereas the blocking of ICA512 autoantibodies with recombinant phogrin was only partial (mean inhibition of 58.9 +/- 3.7%, mean +/- SE). Binding and competition analysis using multiple chimeric ICA512/phogrin constructs demonstrated that a major unique epitope for ICA512 autoantibodies is localized to amino acids 762-887. A conformational epitope associated with the carboxy-terminal 31 amino acids of ICA512 was recognized by one-third of sera, and a minor epitope is located on amino acids 601-762 of ICA512. The major epitopes for phogrin-selective autoantibodies were localized to amino acids 640-922 of phogrin. Sequential serum samples were analyzed in 22 relatives who expressed ICA512/phogrin autoantibodies. Intramolecular epitope spreading was found for 5 of 13 relatives who have progressed to type 1 diabetes. Among nine relatives who have remained nondiabetic, three demonstrated a decrease in the number of epitopes recognized. These studies highlight the complexity of autoantibody recognition of ICA512/phogrin and are consistent with the hypothesis that ICA512/phogrin may be recognized as a consequence of beta-cell destruction.