Assessing the prediction of type 2 diabetes risk using polygenic and clinical risk scores in South Asian study populations

Background

Genome-wide polygenic risk scores (PRS) have shown high specificity and sensitivity in predicting type 2 diabetes (T2D) risk in Europeans. However, the PRS-driven information and its clinical significance in non-Europeans are underrepresented. We examined the predictive efficacy and transferability of PRS models using variant information derived from genome-wide studies of Asian Indians (AIs) (PRSAI) and Europeans (PRSEU) using 13,974 AI individuals.

Methods

Weighted PRS models were constructed and analyzed on 4602 individuals from the Asian Indian Diabetes Heart Study/Sikh Diabetes Study (AIDHS/SDS) as discovery/training and test/validation datasets. The results were further replicated in 9372 South Asian individuals from UK Biobank (UKBB). We also assessed the performance of each PRS model by combining data of the clinical risk score (CRS).

Results

Both genetic models (PRSAI and PRSEU) successfully predicted the T2D risk. However, the PRSAI revealed 13.2% odds ratio (OR) 1.80 [95% confidence interval (CI) 1.63-1.97; p = 1.6 × 10-152] and 12.2% OR 1.38 (95% CI 1.30-1.46; p = 7.1 × 10-237) superior performance in AIDHS/SDS and UKBB validation sets, respectively. Comparing individuals of extreme PRS (ninth decile) with the average PRS (fifth decile), PRSAI showed about two-fold OR 20.73 (95% CI 10.27-41.83; p = 2.7 × 10-17) and 1.4-fold OR 3.19 (95% CI 2.51-4.06; p = 4.8 × 10-21) higher predictability to identify subgroups with higher genetic risk than the PRSEU. Combining PRS and CRS improved the area under the curve from 0.74 to 0.79 in PRSAI and 0.72 to 0.75 in PRSEU.

Conclusion

Our data suggest the need for extending genetic and clinical studies in varied ethnic groups to exploit the full clinical potential of PRS as a risk prediction tool in diverse study populations.

Ethnic differences in ApoC-III concentration and the risk of cardiovascular disease: No evidence for the cardioprotective role of rare/loss of function APOC3 variants in non-Europeans

BACKGROUND

Hypertriglyceridemia is as an independent risk factor for cardiovascular disease (CVD). Apolipoprotein C-III (ApoC-III) is known to regulate triglyceride (TG) metabolism. However, the causal association between ApoC-III and CVD development is unclear. The objectives were to examine the impact of ApoC-III concentration on TG and lipoproteins and investigate the role of known rare loss-of-function APOC3 variants for modulating ApoC-III, TG concentrations and CVD risk in different ethnic groups.

METHODS

Plasma ApoC-III levels were measured in a multiethnic sample of 518 individuals comprising 271 Asian Indians (Sikhs), 87 Caucasians, 80 African Americans, and 80 Hispanics.

RESULTS

ApoC-III levels showed a robust association with TG in Asian Indians (r = 0.5, p = 1.1 × 10^-23), Caucasians (r = 0.4, p = 7.2 × 10^-4), and Hispanics (r = 0.9, p = 2.7x × 10^-28). African Americans had lowest ApoC-III and TG concentrations and highest (44%) prevalence of coronary artery disease (CAD). ApoC-III levels correlated with fasting blood glucose (r = 0.25, p = 6.1 × 10^-5) in Asian Indians and central adiposity in Hispanics (waist: r = 0.22, p = 0.05; waist-hip ratio: r = 0.24, p = 0.04). The carriers of rare variants IVS1-2G-A (rs373975305); A43T (rs147210663) and IVS3 + 1G-T (rs140621530) showed high TG but not low ApoC-III levels in Asian Indians and Caucasians.

CONCLUSION

These results highlight the challenges of generalizing antisense ApoC-III inhibition for treating atherosclerotic disease in dyslipidemia that may benefit only specific sub-populations. The observed ethnic differences in ApoC-III concentrations and CAD risk factors, emphasize in-depth genetic and metabolomics evaluations on diverse ancestries.

APOC3 genetic variation, serum triglycerides, and risk of coronary artery disease in Asian Indians, Europeans, and other ethnic groups

BACKGROUND

Hypertriglyceridemia has emerged as a critical coronary artery disease (CAD) risk factor. Rare loss-of-function (LoF) variants in apolipoprotein C-III have been reported to reduce triglycerides (TG) and are cardioprotective in American Indians and Europeans. However, there is a lack of data in other Europeans and non-Europeans. Also, whether genetically increased plasma TG due to ApoC-III is causally associated with increased CAD risk is still unclear and inconsistent. The objectives of this study were to verify the cardioprotective role of earlier reported six LoF variants of APOC3 in South Asians and other multi-ethnic cohorts and to evaluate the causal association of TG raising common variants for increasing CAD risk.

METHODS

We performed gene-centric and Mendelian randomization analyses and evaluated the role of genetic variation encompassing APOC3 for affecting circulating TG and the risk for developing CAD.

RESULTS

One rare LoF variant (rs138326449) with a 37% reduction in TG was associated with lowered risk for CAD in Europeans (p = 0.007), but we could not confirm this association in Asian Indians (p = 0.641). Our data could not validate the cardioprotective role of other five LoF variants analysed. A common variant rs5128 in the APOC3 was strongly associated with elevated TG levels showing a p-value 2.8 × 10- 424. Measures of plasma ApoC-III in a small subset of Sikhs revealed a 37% increase in ApoC-III concentrations among homozygous mutant carriers than the wild-type carriers of rs5128. A genetically instrumented per 1SD increment of plasma TG level of 15 mg/dL would cause a mild increase (3%) in the risk for CAD (p = 0.042).

CONCLUSIONS

Our results highlight the challenges of inclusion of rare variant information in clinical risk assessment and the generalizability of implementation of ApoC-III inhibition for treating atherosclerotic disease. More studies would be needed to confirm whether genetically raised TG and ApoC-III concentrations would increase CAD risk.

A Bidirectional Mendelian Randomization Study to evaluate the causal role of reduced blood vitamin D levels with type 2 diabetes risk in South Asians and Europeans

Context

Multiple observational studies have reported an inverse relationship between 25-hydroxyvitamin D concentrations (25(OH)D) and type 2 diabetes (T2D). However, the results of short- and long-term interventional trials concerning the relationship between 25(OH)D and T2D risk have been inconsistent.

Objectives and methods

To evaluate the causal role of reduced blood 25(OH)D in T2D, here we have performed a bidirectional Mendelian randomization study using 59,890 individuals (5,862 T2D cases and 54,028 controls) from European and Asian Indian ancestries. We used six known SNPs, including three T2D SNPs and three vitamin D pathway SNPs, as a genetic instrument to evaluate the causality and direction of the association between T2D and circulating 25(OH)D concentration.

Results

Results of the combined meta-analysis of eight participating studies showed that a composite score of three T2D SNPs would significantly increase T2D risk by an odds ratio (OR) of 1.24, p = 1.82 × 10^–32; Z score 11.86, which, however, had no significant association with 25(OH)D status (Beta -0.02nmol/L ± SE 0.01nmol/L; p = 0.83; Z score -0.21). Likewise, the genetically instrumented composite score of 25(OH)D lowering alleles significantly decreased 25(OH)D concentrations (-2.1nmol/L ± SE 0.1nmol/L, p = 7.92 × 10^–78; Z score -18.68) but was not associated with increased risk for T2D (OR 1.00, p = 0.12; Z score 1.54). However, using 25(OH)D synthesis SNP (DHCR7; rs12785878) as an individual genetic instrument, a per allele reduction of 25(OH)D concentration (-4.2nmol/L ± SE 0.3nmol/L) was predicted to increase T2D risk by 5%, p = 0.004; Z score 2.84. This effect, however, was not seen in other 25(OH)D SNPs (GC rs2282679, CYP2R1 rs12794714) when used as an individual instrument.

Conclusion

Our new data on this bidirectional Mendelian randomization study suggests that genetically instrumented T2D risk does not cause changes in 25(OH)D levels. However, genetically regulated 25(OH)D deficiency due to vitamin D synthesis gene (DHCR7) may influence the risk of T2D.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12937-021-00725-1.

Obesity genetics and cardiometabolic health: Potential for risk prediction

The increasing burden of obesity worldwide and its effect on cardiovascular disease (CVD) risk is an opportunity for evaluation of preventive approaches. Both obesity and CVD have a genetic background and polymorphisms within genes which enhance expression of variant proteins that influence CVD in obesity. Genome-based prediction may therefore be a feasible strategy, but the identification of genetically driven risk factors for CVD manifesting as clinically recognized phenotypes is a major challenge. Clusters of such risk factors include hyperglycaemia, hypertension, ectopic liver fat, and inflammation. All involve multiple genetic pathways having complex interactions with variable environmental influences. The factors that make significant contributions to CVD risk include altered carbohydrate homeostasis, ectopic deposition of fat in muscle and liver, and inflammation, with contributions from the gut microbiome. A futuristic model depends on harnessing the predictive power of plausible genetic variants, phenotype reversibility, and effective therapeutic choices based on genotype-phenotype interactions. Inverting disease phenotypes into ideal cardiovascular health metrics could improve genetic and epigenetic assessment, and form the basis of a future model for risk detection and early intervention.

Vitamin D Status, Gender Differences, and Cardiometabolic Health Disparities

BACKGROUND

Vitamin D deficiency is an unrecognized epidemic found in India and also worldwide. Despite the high prevalence of diabetes among Indians, there is a paucity of data showing the relationship between vitamin D status and cardiometabolic disparities. In this study, we have examined the relationship between vitamin D and cardiometabolic traits in a population from India.

METHODS

Circulating 25(OH)D levels were measured in 3,879 participants from the Asian Indian Diabetic Heart Study using ELISA kits.

RESULTS

Vitamin D levels were significantly reduced (p < 0.0001) in both men and women with obesity. However, compared to women, serum vitamin D was consistently lower in men (p < 0.02), irrespective of the presence of obesity and type 2 diabetes. Multivariate regression revealed strong interaction of vitamin D with body mass index that resulted in increased fasting glucose (p = 0.001) and reduced homeostasis model assessment of β-cell function (HOMA-B; p = 0.01) in normoglycemic individuals. However, in gender-stratified analysis, this association was restricted to men for both fasting glucose (p = 2.4 × 10-4) and HOMA-B (p = 0.001).

CONCLUSIONS

Our findings suggest that vitamin D deficiency may significantly enhance the risk of cardiometabolic disease among Asian Indians. Future randomized trials and genetic studies are expected to clarify the underlying mechanisms for gender differences in vitamin D deficiency, and whether vitamin D-driven improvement in testosterone may contribute to beneficial cardiometabolic outcomes in men.

Genome-wide association study of 25(OH) Vitamin D concentrations in Punjabi Sikhs: Results of the Asian Indian diabetic heart study

Vitamin D deficiency is implicated in multiple disease conditions and accumulating evidence supports that the variation in serum vitamin D (25(OH)D) levels, including deficiency, is under strong genetic control. However, the underlying genetic mechanism associated with vitamin 25(OH)D concentrations is poorly understood. We earlier reported a very high prevalence of vitamin D deficiency associated with an increased risk for type 2 diabetes and obesity in a Punjabi Sikh diabetic cohort as part of the Asian Indian diabetic heart study (AIDHS). Here we have performed the first genome-wide association study (GWAS) of serum 25(OH)D on 3538 individuals from this Punjabi Sikh population. Our discovery GWAS comprised of 1387 subjects followed by validation of 24 putative SNPs (P<10(-4)) using an independent replication sample (n=2151) from the same population by direct genotyping. A novel locus at chromosome 20p11.21 represented by rs2207173 with minor allele frequency (MAF) 0.29, [β=-0.13, p=4.47×10(-9)] between FOXA2 and SSTR4 was identified to be associated with 25(OH)D levels. Another suggestive association signal at rs11586313 (MAF 0.54) [β=0.90; p=1.36×10(-6)] was found within the regulatory region of the IVL gene on chromosome 1q21.3. Additionally, our study replicated 3 of 5 known GWAS genes associated with 25(OH)D concentrations including GC (p=0.007) and CYP2R1 (p=0.019) reported in Europeans and the DAB1 (p=0.003), reported in Hispanics. Identification of novel association signals in biologically plausible regions with 25(OH)D metabolism will provide new molecular insights on genetic drivers of vitamin D status and its implications in health disparities.

Association of APOE polymorphisms with diabetes and cardiometabolic risk factors and the role of APOE genotypes in response to anti-diabetic therapy: results from the AIDHS/SDS on a South Asian population

BACKGROUND AND OBJECTIVES

Apolipoprotein E (APOE) gene polymorphisms have been examined extensively in multiple global populations particularly due to their crucial role in lipid metabolism and cardiovascular disease. However, the overall contribution of APOE polymorphisms in type 2 diabetes (T2D) and coronary artery disease (CAD) in South Asians is still under-investigated. The objectives of this investigation were: 1) to evaluate the distribution of APOE polymorphisms in a large diabetic case-control sample from South Asia, 2) to examine the impact of APOE polymorphisms on quantitative risk factors of T2D and CAD, and 3) to explore the contribution of APOE genotypes in the response to anti-diabetic therapy.

SUBJECTS AND METHODS

A total of 3564 individuals (1956 T2D cases and 1608 controls) used in this study were part of the Asian Indian Diabetic Heart Study/Sikh Diabetes Study (AIDHS/SDS). We assessed the association of APOE polymorphisms with T2D, CAD and cardiometabolic traits using logistic and linear regression analysis.

RESULTS AND CONCLUSIONS

No significant differences in the distribution of APOE genotypes were observed between T2D and CAD cases and controls. The APOE4 genotype carriers had moderately higher diastolic blood pressure (BP) (p=0.022), and lower HDL-cholesterol (p=0.026) compared to E4 non-carriers. Overall, the APOE genotype was not a significant predictor of cardiometabolic disease in this population. Further stratification of data from diabetic patients by APOE genotypes and anti-hyperglycemic agents revealed a significant (~23%) decrease in 2-hour glucose (p=0.004) and ~7% decrease in systolic BP (p<0.001) among APOE4 carriers compared to non-carriers on metformin and sulphonylurea (SU) combination therapy, and no such differences were seen in patients on other agents. Our preliminary findings point to the need for evaluating population-specific genetic variation and its interactions with therapeutic effects.

Secondary hypertriglyceridemia in children and adolescents

Secondary dyslipidemia with predominant hypertriglyceridemia may occur as a consequence of both common and rare causes. After accounting for obesity and associated insulin resistance, clinicians should carefully consider other contributing factors and conditions. Genetic background and causative factors prevail during gestation, infancy, and childhood and continue in adults. Elevations in triglyceride (TG) are associated with transfer of TG to high-density lipoprotein (HDL) and low-density lipoprotein (LDL) resulting in lipolysis, HDL degradation, and formation of atherogenic LDL particles. Defining and treating the underlying cause is the first step toward restoring the lipids and lipoproteins to normal, especially in cases with severe hypertriglyceridemia, who are at risk for acute pancreatitis. Disorders involving the liver, kidney, endocrine, and immune systems and medications need to be considered. Rare diseases such as lipodystrophy and glycogen storage disease are particularly challenging, and there have been promising new developments. Treatment depends on the severity; prevention of acute pancreatitis being a priority in severe cases and lifestyle modification being a foundation for general management followed by targeting TG and predictors of coronary artery disease such as LDL cholesterol and non-HDL cholesterol, when they exceed cutpoints.

Early childhood nutrition in an American Indian community: educational strategy for obesity prevention

Prevailing infant and toddler feeding practices in an American Indian community were assessed to explore the feasibility of improvement by implementation of a maternal education program. A survey of prevailing nutritional practice was the basis for design of an instruction program on infant nutrition for mothers during pregnancy. Follow-up assessments provided information on feasibility, and requirements for an effective program. Failure to sustain breast-feeding, low fruit and vegetable intake, low fiber intake, consumption of sweetened beverages, low milk consumption and low vitamin D intake were identified as persisting problems. We conclude that infant and toddler feeding practices are comparable to national trends, but suboptimal and conducive to promoting early obesity and diabetes in a susceptible community. A successful education-based intervention strategy beginning in pregnancy appears feasible if psychosocial, environmental, and economic barriers can be addressed.

Genetic determinants of cardiometabolic risk: a proposed model for phenotype association and interaction

This review provides a translational and unifying summary of metabolic syndrome genetics and highlights evidence that genetic studies are starting to unravel and untangle origins of the complex and challenging cluster of disease phenotypes. The associated genes effectively express in the brain, liver, kidney, arterial endothelium, adipocytes, myocytes, and β cells. Progression of syndrome traits has been associated with ectopic lipid accumulation in the arterial wall, visceral adipocytes, myocytes, and liver. Thus, it follows that the genetics of dyslipidemia, obesity, and nonalcoholic fatty liver disease are central in triggering progression of the syndrome to overt expression of disease traits and have become a key focus of interest for early detection and for designing prevention and treatments. To support the "birds' eye view" approach, we provide a road-map depicting commonality and interrelationships between the traits and their genetic and environmental determinants based on known risk factors, metabolic pathways, pharmacologic targets, treatment responses, gene networks, pleiotropy, and association with circadian rhythm. Although only a small portion of the known heritability is accounted for and there is insufficient support for clinical application of gene-based prediction models, there is direction and encouraging progress in a rapidly moving field that is beginning to show clinical relevance.

Sex differences in HDL ApoC-III in American Indian youth

Background

Since American Indians are predisposed to type 2 diabetes (DM2) and associated cardiovascular risk, Cherokee boys and girls (n = 917) were studied to determine whether BMI Z (body mass index Z score) is associated with the apoC-III (apolipoprotein C-III) content of HDL (high density lipoprotein), a previously reported predictor of DM2.

Methods

An ad hoc cross-sectional analysis was conducted on a previously studied cohort. Participants were grouped by gender-specific age groups (5 to 9, 10 to 14 and 15 to 19 years). ApoA-I (apolipoprotein A-I) and HDL apoC-III were assayed by electroimmunoassay. ApoC-III was measured in whole plasma, and in HDL to determine the molar proportion to apoA-I. General linear models were used to assess association.

Results

The HDL apoC-III to apoA-I molar ratio increased by BMI Z quartile in girls aged 10–14 years (p < 0.05 for linear trend, p < 0.05 for difference in BMI Z quartile IV vs. I to III) and aged 15–19 years (p < 0.05 for trend). In boys the increase by BMI Z occurred only at ages 15–19 years (p < 0.01 for trend and for quartile difference).

Conclusions

ApoC-III showed an obesity-related increase relative to apoA-I during adolescence beginning in girls aged 10 to 14 years and in boys aged 15 to 19 years. The earlier changes in girls may alter HDL’s protective properties on the β-cell and contribute to their increased risk for DM2.

Sex differences in cardiovascular disease risk in adolescents with type 1 diabetes

BACKGROUND

Cardiovascular disease is seen at a younger age and at a higher prevalence in patients with type 1 diabetes than in the general population. It is well described that women with type 1 diabetes have a higher relative risk of cardiovascular disease than men with type 1 diabetes, unlike that seen in the general population. The pathophysiology behind this is unknown.

OBJECTIVE

We performed a cross-sectional study to examine sex differences in cardiovascular disease risk factors in adolescents with type 1 diabetes between ages 13 and 20 years, compared with children of a similar age without type 1 diabetes.

METHODS

All patients underwent a dual energy x-ray absorptiometry scan to measure body composition and a pulse wave test measure of arterial elasticity. Fasting serum lipid levels, apolipoprotein B, and apolipoprotein C-III levels were measured in each patient. Twenty-nine children with type 1 diabetes (10 girls, 19 boys) and 37 healthy children (18 girls, 19 boys) participated.

RESULTS

Although no sex differences for body mass index (P = 0.91) and glycosylated hemoglobin (P = 0.69) were seen, girls with type 1 diabetes had a significantly higher percent trunk fat compared with boys (P = 0.004). No sex differences were found (P > 0.05) for percent trunk fat in adolescents without diabetes. There was no sex difference among any other cardiovascular risk factors in either children with or without diabetes.

CONCLUSIONS

Female adolescents with type 1 diabetes have more centrally distributed fat, which may contribute to their relatively higher cardiovascular disease risk. Attenuation of the central distribution of fat through exercise and dietary modifications may help ameliorate their subsequent cardiovascular disease burden.

Vitamin D Deficiency and Cardio-Metabolic Risk in a North Indian Community with Highly Prevalent Type 2 Diabetes

OBJECTIVE

The purpose of this investigation was to examine serum vitamin D status in a population of Punjabi ancestry from Northern India with a high prevalence of type 2 diabetes (T2D) and evaluate the effects of 25(OH)D levels on cardio-metabolic traits.

RESEARCH DESIGN AND METHODS

We assessed cardiovascular risk factors and 25(OH)D levels in 1,765 participants (887 T2D cases, 878 normoglycemic controls).

RESULTS

76% of individuals were deficient (<50 nmol/L) in vitamin D. A higher percentage of T2D participants(83%) were vitamin D deficient compared to normoglycemic controls (68%)(p<0.0001).The prevalence of vitamin D deficiency increased progressively with body mass index (BMI) categories (p<0.0001): BMI<23 kg/m², 65%; BMI 23-27.5 kg/m², 75%; and BMI>27.5 kg/m², 81%. T2D participants had significantly decreased serum 25(OH)D levels (β=-0.41, p=2.8 × 10^-20). Individuals with low serum 25(OH)D had elevated fasting glucose(β=-0.18, p=0.022), BMI (β=-0.71, p=1.4 × 10^-7) and systolic blood pressure (β=-1.68, p=0.006). A positive association of increased 25(OH)D with HOMA-B (β=0.17, p=8.0×10^-6), and C-peptide (β=0.09, 0.017) was observed. Non-medicated, normoglycemic, non-hypertensive individuals classified as vitamin D deficient (n=289) exhibited a significant increase in fasting glucose (p=0.02) and BMI (p<0.0001) as well as a significant decrease in C-peptide (p<0.0001) and amylin (p<0.0001) compared to vitamin D sufficient controls (n=150).

CONCLUSIONS

Vitamin D deficiency appears to be a significant risk factor for T2D severity and associated cardio-metabolic risk. Early intervention may be considered to improve prevention of T2D related cardiovascular complications.

Type 2 Diabetes Genetics: Beyond GWAS

The global epidemic of type 2 diabetes mellitus (T2D) is one of the most challenging problems of the 21(st) century leading cause of and the fifth death worldwide. Substantial evidence suggests that T2D is a multifactorial disease with a strong genetic component. Recent genome-wide association studies (GWAS) have successfully identified and replicated nearly 75 susceptibility loci associated with T2D and related metabolic traits, mostly in Europeans, and some in African, and South Asian populations. The GWAS serve as a starting point for future genetic and functional studies since the mechanisms of action by which these associated loci influence disease is still unclear and it is difficult to predict potential implication of these findings in clinical settings. Despite extensive replication, no study has unequivocally demonstrated their clinical role in the disease management beyond progression to T2D from impaired glucose tolerance. However, these studies are revealing new molecular pathways underlying diabetes etiology, gene-environment interactions, epigenetic modifications, and gene function. This review highlights evolving progress made in the rapidly moving field of T2D genetics that is starting to unravel the pathophysiology of a complex phenotype and has potential to show clinical relevance in the near future.

Partial defect in the cholesterol side-chain cleavage enzyme P450scc (CYP11A1) resembling nonclassic congenital lipoid adrenal hyperplasia

CONTEXT

The cholesterol side-chain cleavage enzyme (P450scc), encoded by the CYP11A1 gene, converts cholesterol to pregnenolone to initiate steroidogenesis. Genetic defects in P450scc cause a rare autosomal recessive disorder that is clinically indistinguishable from congenital lipoid adrenal hyperplasia (lipoid CAH). Nonclassic lipoid CAH is a recently recognized disorder caused by mutations in the steroidogenic acute regulatory protein (StAR) that retain partial function.

OBJECTIVE

We describe two siblings with hormonal findings suggesting nonclassic lipoid CAH, who had a P450scc mutation that retains partial function.

PATIENTS AND METHODS

A 46,XY male presented with underdeveloped genitalia and partial adrenal insufficiency; his 46,XX sister presented with adrenal insufficiency. Hormonal studies suggested nonclassic lipoid CAH. Sequencing of the StAR gene was normal, but compound heterozygous mutations were found in the CYP11A1 gene. Mutations were recreated in the F2 plasmid expressing a fusion protein of the cholesterol side-chain cleavage system. P450scc activity was measured as Vmax/Km for pregnenolone production in transfected COS-1 cells.

RESULTS

The patients were compound heterozygous for the previously described frameshift mutation 835delA and the novel missense mutation A269V. When expressed in the P450scc moiety of F2, the A269V mutant retained 11% activity of the wild-type F2 protein.

CONCLUSIONS

There is a broad clinical spectrum of P450scc deficiency. Partial loss-of-function CYP11A1 mutation can present with a hormonal phenotype indistinguishable from nonclassic lipoid CAH.

Impact of type 1 diabetes and body weight status on cardiovascular risk factors in adolescent children

Type 1 diabetes (T1D) is a risk factor for cardiovascular disease. However, it is unclear whether increased body weight amplifies that risk in T1D patients. This is a cross-sectional study examining the presence of cardiovascular risk factors in normal and overweight children, both with and without T1D. Sixty-six children (aged 16±2.2 years) were included in one of the following groups: (T1D and normal weight, T1D and overweight, healthy and normal weight, and healthy and overweight). A fasting blood sample was analyzed for lipid profile (triglyceride, cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol), apolipoprotein B (apoB), and apolipoprotein C-III (apoC-III) levels. Body composition was determined by dual energy x-ray absorptiometry and vascular elasticity by HDI/Pulsewave CR-2000 (Hypertension Diagnostics, Eagan, MN). Statistical analyses examined the effect of T1D and body weight status and their interactions on cardiovascular risk parameters. In this study, the authors were unable to demonstrate an additive effect of body weight status and T1D on cardiovascular risk profile. However, subgroup analysis of patients with T1D revealed higher apoC-III levels in overweight patients with T1D (P=.0453) compared with normal-weight diabetic children. Most notably, there was a direct relationship of small artery elasticity to body weight status. This seemingly paradoxical observation supports recent data and warrants further investigation.

Two new unrelated cases of hereditary 1,25-dihydroxyvitamin D-resistant rickets with alopecia resulting from the same novel nonsense mutation in the vitamin D receptor gene

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) an important regulator of bone homeostasis, mediates its actions by binding to the vitamin D receptor (VDR), a nuclear transcription factor. Mutations in the VDR cause the rare genetic disease hereditary vitamin D resistant rickets (HVDRR). In this study, we examined two unrelated young female patients who exhibited severe early onset rickets, hypocalcemia, and hypophosphatemia. Both patients had partial alopecia but with different unusual patterns of scant hair. Sequencing of the VDR gene showed that both patients harbored the same unique nonsense mutation that resulted in a premature stop codon (R50X). Skin fibroblasts from patient #1 were devoid of VDR protein and 1,25(OH)2D3 treatment of these cells failed to induce CYP24A1 gene expression, a marker of 1,25(OH)2D3 action. In conclusion, we identified a novel nonsense mutation in the VDR gene in two patients with HVDRR and alopecia. The mutation truncates the VDR protein and causes 1,25(OH)2D3 resistance.

Vascular health in children and adolescents: effects of obesity and diabetes

The foundations for cardiovascular disease in adults are laid in childhood and accelerated by the presence of comorbid conditions, such as obesity, diabetes, hypertension, and dyslipidemia. Early detection of vascular dysfunction is an important clinical objective to identify those at risk for subsequent cardiovascular morbidity and events, and to initiate behavioral and medical interventions to reduce risk. Typically, cardiovascular screening is recommended for young adults, especially in people with a family history of cardiovascular conditions. Children and adolescents were once considered to be at low risk, but with the growing health concerns related to sedentary lifestyle, poor diet and obesity, cardiovascular screening may be needed earlier so that interventions to improve cardiovascular health can be initiated. This review describes comorbid conditions that increase cardiovascular risk in youth, namely obesity and diabetes, and describes noninvasive methods to objectively detect vascular disease and quantify vascular function and structure through measurements of endothelial function, arterial compliance, and intima-media thickness. Additionally, current strategies directed toward prevention of vascular disease in these populations, including exercise, dietary interventions and pharmacological therapy are described.

Ring chromosome 9 [r(9)(p24q34)]: a report of two cases

We report clinical and molecular cytogenetic studies in two patients with ring chromosome 9. Cytogenetics and fluorescent in situ hybridization (FISH) analysis using the p16 gene probe on 9p21, the ABL gene on 9q34, chromosome 9 alpha satellite-centromeric probes, and TelVision 9p and 9q probes which identify subtelomere-specific sequences on chromosome 9p and 9q, revealed 46,XX,r(9)(p24q34).ish r(9)(305J7-T7-,p16+,ABL+, D9S325-) and 46XY,r(9)(p24q34).ish r(9)(305J7-T7-,p16+,ABL+, D9S325-). Based on FISH analysis at least 115 kb was deleted on terminal 9p, and at least 95 kb from terminal 9q. In comparison with other reports of r(9), deletion 9p, and deletion 9q, both patients had clinical characteristics of ring 9 and additional features of deletion 9q or deletion 9p syndrome. The variability between the two cases with r(9) despite similar breakpoints identified by GTG-banding and FISH may be explained by submicroscopic differences between deletion breakpoints, ring instability, interaction of other genes on the phenotype, and variation in fetal environmental conditions.

Prolongation of growth by treatment of 11-hydroxylase deficiency with depot-leuprolide, growth hormone, and hydrocortisone

A 4-10/12 year-old boy presented with tall stature and advanced secondary sexual characteristics. His bone age was 13 years giving him a height prediction of 147 cm. An initial 11-deoxycortisol level of 13,770 ng/dl and associated hypertension suggested the diagnosis of 11-hydroxylase deficiency, which was confirmed by dexamethasone suppression and genotyping. Treatment strategy was based on the premise that known hypothalamic priming resulting in early pubertal development could be averted by delaying puberty with leuprolide; also that effects of hydrocortisone and leuprolide on attenuating growth could be counteracted by growth hormone. The combined treatment resulted in a final height at age 12 years which was 25.4 cm greater than predicted, and bone density above average. We conclude that delaying puberty until an appropriate age, offsetting growth suppression, and improving bone mineralization can be effectively achieved using glucocorticoids, leuprolide and growth hormone in patients with 11-hydroxylase deficiency.

Ethnic differences in fasting glucose, insulin resistance and lipid profiles in obese adolescents

Children and adolescents with obesity are increasingly referred to the pediatric endocrinology clinic at OU Children's Hospital for evaluation and initiation of preventive measures. During the summer of 2004 we conducted a retrospective review of cases to determine the prevalence of fasting insulin resistance and dyslipidemia; to study associations and differences due to ethnic background; and compare values with similar patients seen at four Indian Health Service clinics. We observed the highest prevalence of dyslipidemia in Caucasian youth. The prevalence of high fasting glucose and mean glucose values were higher in the obese Native American youth than in African Americans or Caucasians. The elevated glucose levels in young Native Americans may be associated with their increased risk for type 2 diabetes compared to other races; but Caucasians are more prone to dyslipidemia. Effective methods are needed to detect, prevent and treat diabetes and cardiovascular risk in children and adolescents.

Body mass index and high-density lipoproteins in Cherokee Indian children and adolescents

Native Americans are predisposed to insulin resistance and associated cardiovascular risk. Therefore, we studied whether BMI (body mass index) in a population of Cherokee children and adolescents is associated with HDL-C (HDL cholesterol), and the HDL particles Lp (lipoprotein) A-I and LpA-I:A-II. Subjects were grouped by BMI Z score quartiles within three gender-specific age brackets (5-9, 10-14, and 15-19 y) to examine for trends in lipoprotein and HOMA-IR (homeostasis index insulin resistance) values associated with adiposity and age. HDL-C decreased by BMI Z score quartiles in all three age groups for both genders. HDL-C, LpA-I, and LpA-I:A-II decreased with age in boys but not girls. Log HOMA-IR increased by BMI Z score quartiles in all three age groups for both genders. Linear regression modeling showed BMI Z score, triglyceride, and age to be associated with HDL-C, whereas HOMA-IR was associated with LpA-I:A-II but not with HDL-C or LpA-I. When waist circumference was substituted for BMI Z score in the same models, it was associated with HDL-C and both lipoprotein particles. In conclusion, adiposity is more associated with HDL-C lowering than with declines in the lipoprotein particles. HOMA-IR is less associated with HDL-C but may selectively influence LpA-I:A-II. Greater decreases in HDL-C, LpA-I, and LpA-I:A-II with age in boys is attributed to gender-specific hormonal changes. The early onset of HDL lowering in these Native American children and adolescents, particularly boys, warrants intervention strategies to prevent obesity and associated cardiovascular risk.

ApoC-III bound to apoB-containing lipoproteins increase with insulin resistance in Cherokee Indian youth

Because Native Americans are predisposed to obesity and type 2 diabetes associated with coronary artery disease, we assessed whether apoC-III bound to apoB-containing (LpB:C-III) and apoA-containing (LpA:C-III) lipoproteins, total apoC-III, apoB, and plasma lipids are associated with insulin resistance, body mass index (BMI), and waist circumference in Cherokee children and adolescents aged 5 to 19 years (n = 975). A cross-sectional analysis was done to determine associations of the lipoproteins with the homeostasis index (HOMA-IR) and BMI. When the data were grouped by quartiles for HOMA-IR and separated by three 5-year age groups (5-9, 10-14, and 15-19 years), the trend for LpB:C-III, triglyceride, and BMI z score to increase was significant for all age groups and both genders (P < .001). The trend to increase LpB:C-III with age was greater in boys (P < .0001) than in girls (P < .05) who tended to plateau after the age of 10 years. In contrast, the ratio of LpA:C-III to LpB:C-III decreased and the decrease was greater in boys (P < .0001) than girls (P < .01). Body mass index z score and waist circumference were correlated with LpB:C-III, triglyceride, apoB, and non-high-density lipoprotein cholesterol within each gender (P < .001). In multiple regression models, LpB:C-III, the dependent variable, was associated with HOMA-IR for both genders. We conclude that increases in LpB:C-III in childhood and adolescence are associated with insulin resistance and obesity supporting the need for prevention programs.

Type 2 diabetes and impaired fasting glucose in American Indians aged 5-40 years: the Cherokee diabetes study

PURPOSE

To estimate the prevalence of type 2 diabetes and impaired fasting glucose (IFG) and to study several potential risk factors for type 2 diabetes among Oklahoma Cherokees aged 5 to 40 years.

METHODS

A random sample of 2205 members of the Cherokee Nation of Oklahoma aged 5 to 40 years was recruited. Demographic, clinical, and laboratory data were collected. Type 2 diabetes and IFG were determined using the 1997 American Diabetes Association (ADA) criteria. Relationships between type 2 diabetes and potential risk factors were examined by univariate and multivariate regression methods.

RESULTS

According to ADA criteria, the age-adjusted prevalence proportions of type 2 diabetes were 4.3% in females and 4.8% in males. Among the 89 individuals who had type 2 diabetes, 31 were newly diagnosed. Thirty-two (1.5%, 18 females and 14 males) were found to have IFG. The prevalence of type 2 diabetes and IFG increased with age, number of parents with diabetes, obesity, degree of Indian heritage, high triglyceride value, and low HDL cholesterol.

CONCLUSIONS

The increasing prevalence of type 2 diabetes in young American Indians is alarming. The findings must be disseminated to the Indian communities and their health care providers. Preventive measures and early detection programs must be designed and implemented for children and adolescents in this population.

Ring chromosome 4 in a patient with early onset type 2 diabetes, deafness, and developmental delay

To date, most ring formations of chromosome 4 lose distal 4p and usually include the Wolf-Hirschhorn syndrome region [WHS]. We describe a case with r(4) in a girl who presented without features of WHS; she had mild developmental delay, deafness, short stature, obesity, and the onset of type 2 diabetes in adolescence, a distinctive phenotype. Although 4p was significantly deleted on Giemsa banding, the 4p junction was distal to the WHS and FGFR3 but proximal to the D4S3360 marker. The 4q breakpoint was close to the telomere. The phenotype appears different from previous patients with 4p- or r(4), which have had more extensive 4p deletion.

Childhood obesity: epidemiology, comorbid conditions, psychological ramifications, and clinical recommendations

The prevalence of childhood obesity in the United States has increased dramatically in recent years, doubling in the last 20 years, and is expected to result in a major public health crisis. This epidemic has left no race, socioeconomic status, or age unaffected. Children in Oklahoma are no exception; according to the Centers for Disease Control and Prevention, Morbidity and Mortality Weekly Report, 25% of Oklahoma's adolescents are at risk for overweight or are overweight. In order to address this problem, efforts are underway nationally to institute preventive measures for childhood obesity and its comorbid conditions.

Proteinuric nephropathy in acquired and congenital generalized lipodystrophy: baseline characteristics and course during recombinant leptin therapy

Generalized lipodystrophy is characterized by adipose tissue absence, hypoleptinemia, hypertriglyceridemia, insulin resistance, diabetes, hepatomegaly, and nonalcoholic steatohepatitis. In the course of recruiting patients for treatment with recombinant leptin, we were struck by the frequency and severity of proteinuria. We evaluated 25 patients with generalized lipodystrophy. Eighteen were treated with recombinant leptin, and we have followed 15 on leptin for 4-36 months. We followed renal parameters at baseline and during follow-up visits. Renal biopsies were performed as clinically indicated. At baseline, 22 of 25 patients (88%) had elevated urine albumin excretion (>30 mg/24 h), 15 (60%) had macroalbuminuria (>300 mg/24 h), and five (20%) had nephrotic-range proteinuria (>3500 mg/24 h). Twenty-three (92%) had elevated creatinine clearance (>125 ml/min.1.73 m(2)). Eleven of 15 patients (73%) treated with recombinant leptin exhibited reduction in proteinuria, associated with reduction of hyperfiltration. Four patients who did not improve are discussed individually. Renal biopsy findings were remarkable for focal segmental glomerulosclerosis in four patients, membranoproliferative glomerulonephritis in two patients, and diabetic nephropathy in one patient. In conclusion, generalized lipodystrophy is associated with proteinuria and unique renal pathologies, including focal segmental glomerulosclerosis and membranoproliferative glomerulonephritis. The majority treated with recombinant leptin demonstrated reduction in proteinuria and hyperfiltration.

Expanding metabolic screening of newborns: can the health care industry do better than public health?

In Oklahoma since the early 1990s, all newborns have been screened for four metabolic conditions: phenylketonuria, hypothyroidism, galactosemia and hemoglobinopathies. In 2002, 38 affected babies were diagnosed and one expects they are saved from the complications of late diagnosis such as mental retardation or death from sepsis. With advances in genetics and improved biochemical assays, 86% of states now screen for more disorders than Oklahoma, up to 37 in Mississippi. Six recent patient vignettes illustrate the mortality and morbidity of conditions that are screened for elsewhere but not in Oklahoma. In 2001, the Oklahoma Genetics Advisory Council recommended adding three disorders and the State Health Department forecasts that implementation may be complete in 2007. For now, when a patient asks, "Will my baby be screened for as many metabolic conditions as possible?", two answers represent either the public health or the private health care view. The public health answer is, "The state requires screening for four conditions." The health care system answer is, "We can work with you to get 44 conditions tested for, but it will cost money, may not be reimbursed, and has not been proven effective when done on an individual basis." This dilemma, not unique to newborn screening, might be resolved if professional and public opinion strongly supported early expansion.

Fatal malignant hyperthermia-like syndrome with rhabdomyolysis complicating the presentation of diabetes mellitus in adolescent males

OBJECTIVE

This report describes a new fatal syndrome observed in adolescent males at the initial presentation of diabetes mellitus. The features include hyperglycemic hyperosmolar coma complicated by a malignant hyperthermia-like picture with fever, rhabdomyolysis, and severe cardiovascular instability.

DESIGN

Case series.

SETTING

Pediatric intensive care units of 3 tertiary care facilities in the United States.

PATIENTS

Six adolescent males, 5/6 obese with acanthosis nigricans, 4/6 black.

RESULTS

Four of 6 patients died. Four of 6 patients did not have significant ketosis. Six of 6 patients had increased temperature after the administration of insulin.

CONCLUSIONS

The underlying etiology of this syndrome remains unclear. Possibilities include an underlying metabolic disorder such as a fatty acid oxidation defect, an unrecognized infection, exposure to an unknown toxin, or a genetic predisposition to malignant hyperthermia. Evaluation for all these possibilities and empiric treatment with dantrolene should be considered for this type of patient until this syndrome is better characterized.

Association of acanthosis nigricans with hyperinsulinemia compared with other selected risk factors for type 2 diabetes in Cherokee Indians: the Cherokee Diabetes Study

OBJECTIVE

To report prevalence rates of acanthosis nigricans (AN) and hyperinsulinemia and the association of AN with hyperinsulinemia compared with other known or suspected risk factors for type 2 diabetes in young American Indians.

RESEARCH DESIGN AND METHODS

A random sample of Cherokee Nation members aged 5-40 years was invited to participate in the Cherokee Diabetes Study, a cross-sectional study of type 2 diabetes and its risk factors in a young American Indian population. Data were collected by personal interview, medical history, physical examination (including anthropometric and blood pressure measurements and examination of the neck for AN), and laboratory analyses of blood specimens. Levels of insulin, lipids, and glucose were measured on fasting blood specimens. Diabetes status was determined according to the American Diabetes Association criteria.

RESULTS

A total of 2,205 participants were examined. Overall prevalence rates for AN and hyperinsulinemia were 34.2 and 47.2%, respectively. In general, the rates for both increased with age and degree of Indian heritage and were higher in female subjects, overweight/obese individuals, those with type 2 diabetes, and those with a parental history of type 2 diabetes. In addition, both had significantly higher age- and sex-adjusted means for selected known or suspected risk factors for type 2 diabetes. AN remained significantly associated with hyperinsulinemia (P = 0.0001) in multivariate analysis.

CONCLUSIONS

AN is independently associated with hyperinsulinemia and therefore may be useful as an early indicator of high risk for diabetes.

Body mass index (BMI) in Turner Syndrome before and during growth hormone (GH) therapy

OBJECTIVE

To study whether body mass index (BMI) is different in girls with Turner syndrome (TS) compared to normal girls, and whether BMI in TS is affected by growth hormone (GH) treatment.

DESIGN

A retrospective cross-sectional study.

SUBJECTS

2468 girls with TS enrolled in the National Cooperative Group Study (NCGS), a collaborative surveillance study for assessing GH-treated children.

MEASUREMENTS

BMI and BMI standard deviation score (BMI SDS) at baseline and during GH treatment were computed from height and weight data.

RESULTS

BMI in TS patients increases with age as expected. However, BMI SDS increased starting at about age 9 y. A similar pattern of increase in BMI SDS was observed after each year of GH treatment for up to 4 y, but GH treatment did not change the magnitude of increase. BMI and BMI SDS curves before and during GH treatment were essentially superimposable.

CONCLUSION

These findings suggest that mechanisms specific for TS are responsible for the age-related increase in BMI SDS. This increase was unaffected by GH treatment.

Effect of newborn screening for congenital adrenal hyperplasia

OBJECTIVE

To compare the incidence of diagnosis and morbidity in newborns who were screened with newborns who were not screened for congenital adrenal hyperplasia (CAH).

DESIGN

A retrospective cohort study.

SETTING

Arkansas, Oklahoma, and Texas.

PATIENTS

An unscreened population in Arkansas and Oklahoma (n = 400118) was compared with a screened population in Texas (n = 1613378) during a 5-year period. Simultaneous data were collected on the incidence of diagnosis and associated morbidity in patients with CAH.

MAIN OUTCOME MEASURES

Diagnosis of CAH, age (in days) at diagnosis, and frequency and length of initial hospitalization.

RESULTS

The incidence of diagnosis of classic CAH per 100000 newborns in the unscreened cohort (5.75) and in the screened cohort (6.26) was similar (relative risk, 0.92; 95% confidence interval, 0.58-1.44). The unscreened group had 0.73 fewer male newborns with salt-wasting CAH diagnosed per 100000 newborns (relative risk, 0.73; 95% confidence interval, 0.35-1.56). The median age at diagnosis was 26 days for male newborns with salt-wasting CAH in the unscreened cohort vs 12 days in the screened cohort (z = 2.49; P = .01). Male newborns with simple-virilizing CAH and newborns with nonclassic CAH were detected only in the screened cohort.

CONCLUSIONS

There was not a statistically significant (P = .73) increase in the diagnosis of salt-wasting CAH in the screened cohort. Male newborns benefited as a result of significantly (P = .01) earlier diagnosis, reduced morbidity, and shorter lengths of hospitalization. Large collaborative studies or meta-analyses are needed to determine the life-saving benefits of screening.

Lipoprotein changes in relation to body mass index in Native American adolescents

In view of their known high incidence of noninsulin dependent diabetes (NIDDM), we sought to determine whether Native American (Plains Indian) children and adolescents show evidence of risk factors for both NIDDM and cardiovascular disease. Children and adolescents between the ages of 4 and 19 y were recruited, and field days were organized for data collection, which included height, weight [to compute body mass index (BMI)], waist and hip circumference, family histories, quantum of Native American ancestry, and blood sampling for fasting lipids, apolipoproteins, insulin, and glucose. BMI increased with age in boys and girls and tended to be higher than in Caucasian children. The difference was significant in 5-9-y-old (p < 0.05) and 10-14-y-old (p < 0.05) boys and 10-14-y-old girls (p < 0.001). Ten- to 14-y-old girls in the highest quartile for BMI had higher triglyceride levels (p < 0.05) and lower HDL cholesterol (p < 0.001) when compared with those in the lower quartiles. In contrast, 15-19 y olds in the highest quartile for BMI had higher cholesterol, LDL cholesterol, and apolipoprotein B (p < 0.001). The mean fasting insulin levels were not related to BMI. The data suggest that, within this Plains Indian population, obesity associated with elevated lipid levels tends to begin at an early age in Native American children. Insulin levels do not appear to be related to BMI, a putative index of adiposity, in this population of children known to be prone to NIDDM in adult life.

FH Tulsa-1 and -2: two unique alleles for familial hypercholesterolemia presenting in an affected two-year-old African-American male

A two-year-old African American boy presented with cutaneous xanthomata and extreme hypercholesterolemia. Subsequent studies revealed that the LDL-cholesterol was 1,001 mg/dl and apoB 507 mg/dl. LDL-receptor activity was almost undetectable, which is compatible with the finding of two newly described defective alleles on exon 4 of the LDL-receptor gene coding for part of the ligand-binding domain. One allele contained a 21 base-pair insertion from codon 200 to 207 whereas the other had a point mutation at codon 207. The rarity of genes for FH reported in individuals of African ancestry is discussed.

Lipids and apolipoproteins in growth hormone-deficient children during treatment

The role of growth hormone (GH) in regulating the transport of plasma lipoproteins has not been clearly defined, but past studies suggest that GH may influence cholesterol levels. This protocol was designed to evaluate possible changes in lipid and apolipoprotein status in GH-deficient children and children with neurosecretory dysfunction (NS) before GH therapy and at intervals after GH therapy was started. Twenty children with classic GH deficiency were evaluated, and 28% were hyperlipidemic at the onset of the study. Seven children were evaluated in the NS group, and only one (14%) showed an elevated total cholesterol (TC) greater than 200 mg/dL. The mean TC for all the GH-deficient children was elevated above the normal range, but not for the NS group. The mean apolipoprotein (apo) C-III level and its heparin-precipitated fraction (HP) were also elevated in the GH-deficient group, but only the apo C-III HP was elevated in the NS group. A standard replacement dose of recombinant methionyl GH was used, and therapy had no significant effect on TC or triglyceride (TG) levels. Apo C-III HP, a marker of hypertriglyceridemia, increased after the start of therapy, but no other lipoprotein levels changed significantly in the GH-deficient group. No changes were seen with treatment in the NS group. The longitudinal design of this study allowed demonstration of the later changes in the apolipoproteins and the presence of a distinct subset of patients with both GH deficiency and hypercholesterolemia. This study supports the role of GH in modulating lipid metabolism.

Thyroxine and triiodothyronine autoantibodies in Hashimoto's thyroiditis with severe hormone-resistant hypothyroidism

Severe hypothyroidism in an 8 year-old girl was associated with a paradoxically high free thyroxine (T4), a high TSH level and antimicrosomal antibodies suggestive of Hashimoto's thyroiditis. Low radiolabelled T3 binding to resin in the standard T3 resin uptake test suggested thyroid hormone binding which was subsequently found to be due to antibodies to T4. T4 by equilibrium dialysis was very low confirming that conventional free T4 and total T4 assays overestimated the true values. Subsequent normalization of free T4 by dialysis coincided with a decline in the T4 autoantibody titer allowing a change in treatment from Cytomel (triiodothyronine) to Synthroid (L-thyroxine) while maintaining therapeutic efficacy.

Hyperlipidemia in children

Advances toward improving cardiovascular health of tomorrow's adults lie both in acknowledging that the pathogenesis of atherosclerosis begins in childhood and in considering the influence of environmental factors on genetic endowment of risk. Based on current understanding of lipoprotein transport processes, an array of genetic disorders with various degrees of atherogenicity can be classified according to the predominant lipoprotein density class, as represented by a standard lipid profile, and then further defined by assaying apolipoproteins and their receptors, lipoprotein transport enzymes, or the respective variant genes. Alternatively, a simple and potentially cost-effective representation of multifactorial influences on lipid transport is provided by an assessment of apolipoprotein particle composition using serial immunologic precipitation of apolipoproteins while on their intact plasma lipoproteins. A comprehensive intervention strategy can be based on identification of inherited risk and the effects of nongenetic factors, which include dietary excess, inactivity, disease states, and medications.

Dominantly inherited childhood gigantism resembling Sotos' syndrome

Excessive growth in infancy and onset of puberty at age four was observed in a boy with features resembling Sotos syndrome. Early development of secondary sexual characteristics and advanced osseous maturation were observed. The family history was significant; excessive weight gain tended to occur in female family members in association with rapid growth in infancy and childhood. A delayed insulin response to glucose was observed in both mother and sister, and diabetes developed during his mother's gestation. These observations suggest that undetermined factors associated with excessive growth may be inherited as a dominant trait with variable expression.

Child and Adolescent Athletes With Diabetes

In brief: The common desire to participate in sports can be harnessed to encourage children and adolescents with type 1 diabetes to participate actively in controlling their disease. This is partly because the diabetic who successfully learns to control blood glucose during exercise by wise regulation of diet and insulin is rewarded with enhanced athletic performance. Age, duration of the diabetes, insulin dosage, hypoglycemia, seasonality, training, duration of training periods, and calorie intake must be considered in prescribing specific exercise regimens for diabetic youngsters. To participate in endurance sports, persons with diabetes must manage the effects of exogenous insulin on their normal triphasic metabolic fuel supply derived from muscle, liver, and adipose tissue. If educational guidelines are followed and potential risks due to complications are taken into account, the benefits of regular exercise early in the course of the disease outweigh potential disadvantages.

Plasma lipids and apolipoproteins in a 13-year-old boy with diabetic ketoacidosis and extreme hyperlipidemia

A 13-year-old boy with untreated diabetes presented in severe ketoacidosis (DKA) for the first time with an initial triglyceride (TG) level of 14,461 mg/dl. Serial blood samples were drawn to determine the interrelationships of changes in lipids and apolipoproteins during treatment with insulin and intravenous fluids. The TG level declined to 122 mg/dl in 7 days concomitant with a lowering of apolipoproteins C-II, C-III, E, D, and F. Further observations suggested that the TG-rich lipoproteins underwent degradation associated with a decline in the levels of apolipoproteins associated with very low density lipoprotein (VLDL) in contrast to an increase in high density lipoprotein-cholesterol (HDL-C), ApoA-I and ApoA-II. ApoB and low density lipoprotein cholesterol (LDL-C) were increased transiently. Subsequent therapy with continuous subcutaneous insulin infusion (CSII) were effective in maintaining glucose homeostasis and normolipidemia for 6 months.

Increased levels of HDL-cholesterol and apolipoprotein A-I after intensified insulin therapy for diabetes

Sixteen subjects with insulin-dependent diabetes mellitus were studied to determine whether changes in plasma lipids and apolipoproteins follow intensified control using preprandial doses of regular insulin with an additional dose of NPH insulin before bedtime. The mean total dialy dose of insulin was increased from 1.03 +/- 0.09 to 1.17 +/- 0.44 units/kg throughout the six-month period. Levels of HDL-cholesterol and apolipoprotein A-I increased without significant changes in hemoglobin A1 (HbA1), triglyceride, or cholesterol. These findings suggest that increases in HDL-cholesterol and apolipoprotein A-I were a result of the intensified insulin delivery.

Studies of lipids, lipoproteins, and apolipoproteins in Menkes' disease

Three patients with Menkes' disease, an inherited disorder of copper transport, were studied to determine whether the copper deficiency was associated with a lipoprotein disorder. Hypocuprinemia was documented in all three cases. Two patients had severe copper and ceruloplasmin deficiencies, whereas the third patient had a less severe deficiency. Hypertriglyceridemia was observed in the first patient, and elevations in triglyceride, cholesterol, apolipoprotein B (ApoB), and apolipoprotein C-III (ApoC-III) occurred predominantly in the very low density lipoprotein fraction (VLDL). This patient had normal lipoprotein lipase activity but mild glucose intolerance. The second patient had a borderline high cholesterol level with normal plasma triglycerides and apolipoproteins, whereas the third patient appeared to have normal total cholesterol but slightly higher triglycerides with elevated plasma apolipoprotein E (ApoE). No striking differences were observed in the chemical composition of all lipoprotein subfractions between patients and controls except that the neutral lipid content of VLDL was higher in patients than in controls. The ApoB was initially normal in molecular weight but degraded faster than the controls during storage. The appearance of the major low density lipoprotein (LDL) fraction of the first two patients was opaque white, in contrast to clear yellow in the third patient and in the age- and diet-matched controls. This abnormal appearance of LDL in these patients was associated with low plasma levels of beta-carotene and ceruloplasmin. These findings suggest that decreased serum copper levels may be associated with lipid and lipoprotein abnormalities and may enhance lipid peroxidation of LDL accounting for the color change.(ABSTRACT TRUNCATED AT 250 WORDS)

Hyperlipidemia in acute lymphoblastic leukemia

Studies were conducted on lipemic serum obtained from a 26 month old male to determine possible mechanisms for the association of a Type V hyperlipidemic phenotype with advanced lymphoblastic leukemia (ALL). Antibodies to apolipoproteins and endogenous heparin were not detected as previously reported. Fatty acid analysis of the triglyceride esters revealed a high proportion of stearic-acid (18:0) which was associated with a slower in vitro degradation of very low density lipoproteins (VLDL) by human milk lipoprotein lipase (LPL). This suggests that a cause of the hyperlipidemia could be abnormal composition of triglycerides which render the VLDL a poor substrate for lipoprotein lipase. Hyperlipidemia in leukemia may be more prevalent than previously realized since nine other cases of newly diagnosed ALL have been studied who had moderate hypertriglyceridemia associated with elevated ApoB and low ApoA-I levels, but normal triglyceride composition. These findings suggest that the abnormal triglyceride composition is a late feature of the hyperlipidemia in leukemia, as observed in the case studied.

Familial central diabetes insipidus: vasopressin and nicotine stimulated neurophysin deficiency with subnormal oxytocin and estrogen stimulated neurophysin

Five members of a family with dominantly inherited diabetes insipidus were diagnosed and treated with deamino-d-arginine vasopressin (DDAVP), a vasopressin analogue given intranasally. All subjects demonstrated subnormal levels of arginine vasopressin (AVP) by radioimmunoassay in response to cigarette smoke inhalation, a standardized nicotine stimulation test. Levels of oxytocin (OT) were found to be normal and unstimulated after cigarette inhalation in two subjects, but when two affected male siblings ingested Ovulen, OT and ESN were stimulated to subnormal levels. After twelve months of DDAVP treatment, the low AVP response to nicotine was preserved whereas the carrier protein, nicotine stimulated neurophysin (NSN) remained undetectable.