SNP in the genome-wide association study hotspot on chromosome 9p21 confers susceptibility to diabetic nephropathy in type 1 diabetes

AIMS/HYPOTHESIS: Parental type 2 diabetes mellitus increases the risk of diabetic nephropathy in offspring with type 1 diabetes mellitus. Several single nucleotide polymorphisms (SNPs) that predispose to type 2 diabetes mellitus have recently been identified. It is, however, not known whether such SNPs also confer susceptibility to diabetic nephropathy in patients with type 1 diabetes mellitus. METHODS: We genotyped nine SNPs associated with type 2 diabetes mellitus in genome-wide association studies in the Finnish population, and tested for their association with diabetic nephropathy as well as with severe retinopathy and cardiovascular disease in 2,963 patients with type 1 diabetes mellitus. Replication of significant SNPs was sought in 2,980 patients from three other cohorts. RESULTS: In the discovery cohort, rs10811661 near gene CDKN2A/B was associated with diabetic nephropathy. The association remained after robust Bonferroni correction for the total number of tests performed in this study (OR 1.33 [95% CI 1.14, 1.56], p?=?0.00045, p (36tests)?=?0.016). In the meta-analysis, the combined result for diabetic nephropathy was significant, with a fixed effects p value of 0.011 (OR 1.15 [95% CI 1.02, 1.29]). The association was particularly strong when patients with end-stage renal disease were compared with controls (OR 1.35 [95% CI 1.13, 1.60], p?=?0.00038). The same SNP was also associated with severe retinopathy (OR 1.37 [95% CI 1.10, 1.69] p?=?0.0040), but the association did not remain after Bonferroni correction (p (36tests)?=?0.14). None of the other selected SNPs was associated with nephropathy, severe retinopathy or cardiovascular disease. CONCLUSIONS/INTERPRETATION: A SNP predisposing to type 2 diabetes mellitus, rs10811661 near CDKN2A/B, is associated with diabetic nephropathy in patients with type 1 diabetes mellitus.

Association Testing of Previously Reported Variants in a Large Case-Control Meta-analysis of Diabetic Nephropathy

We formed the GEnetics of Nephropathy–an International Effort (GENIE) consortium to examine previously reported genetic associations with diabetic nephropathy (DN) in type 1 diabetes. GENIE consists of 6,366 similarly ascertained participants of European ancestry with type 1 diabetes, with and without DN, from the All Ireland-Warren 3-Genetics of Kidneys in Diabetes U.K. and Republic of Ireland (U.K.-R.O.I.) collection and the Finnish Diabetic Nephropathy Study (FinnDiane), combined with reanalyzed data from the Genetics of Kidneys in Diabetes U.S. Study (U.S. GoKinD). We found little evidence for the association of the EPO promoter polymorphism, rs161740, with the combined phenotype of proliferative retinopathy and end-stage renal disease in U.K.-R.O.I. (odds ratio [OR] 1.14, P = 0.19) or FinnDiane (OR 1.06, P = 0.60). However, a fixed-effects meta-analysis that included the previously reported cohorts retained a genome-wide significant association with that phenotype (OR 1.31, P = 2 × 10-9). An expanded investigation of the ELMO1 locus and genetic regions reported to be associated with DN in the U.S. GoKinD yielded only nominal statistical significance for these loci. Finally, top candidates identified in a recent meta-analysis failed to reach genome-wide significance. In conclusion, we were unable to replicate most of the previously reported genetic associations for DN, and significance for the EPO promoter association was attenuated.

Breast-feeding and childhood-onset type 1 diabetes:A pooled analysis of individual participant data from 43 observational studies

OBJECTIVE: To investigate if there is a reduced risk of type 1 diabetes in children breastfed or exclusively breastfed by performing a pooled analysis with adjustment for recognized confounders.
RESEARCH DESIGN AND METHODS: Relevant studies were identified from literature searches using MEDLINE, Web of Science, and EMBASE. Authors of relevant studies were asked to provide individual participant data or conduct prespecified analyses. Meta-analysis techniques were used to combine odds ratios (ORs) and investigate heterogeneity between studies.
RESULTS: Data were available from 43 studies including 9,874 patients with type 1 diabetes. Overall, there was a reduction in the risk of diabetes after exclusive breast-feeding for >2 weeks (20 studies; OR = 0.75, 95% CI 0.64-0.88), the association after exclusive breast-feeding for >3 months was weaker (30 studies; OR = 0.87, 95% CI 0.75-1.00), and no association was observed after (nonexclusive) breast-feeding for >2 weeks (28 studies; OR = 0.93, 95% CI 0.81-1.07) or >3 months (29 studies; OR = 0.88, 95% CI 0.78-1.00). These associations were all subject to marked heterogeneity (I(2) = 58, 76, 54, and 68%, respectively). In studies with lower risk of bias, the reduced risk after exclusive breast-feeding for >2 weeks remained (12 studies; OR = 0.86, 95% CI 0.75-0.99), and heterogeneity was reduced (I(2) = 0%). Adjustments for potential confounders altered these estimates very little.
CONCLUSIONS: The pooled analysis suggests weak protective associations between exclusive breast-feeding and type 1 diabetes risk. However, these findings are difficult to interpret because of the marked variation in effect and possible biases (particularly recall bias) inherent in the included studies.

UROTENSIN II FROM THE RIVER LAMPREY (LAMPETRA-FLUVIATILIS), THE SEA LAMPREY (PETROMYZON-MARINUS), AND THE PADDLEFISH (POLYODON SPATHULA)

Urotensin II was isolated from extracts of the whole brain of the river lamprey (Lampetra fluviatilis) and the sea lamprey (Petromyzon marinus). The primary structure of the peptide from both species is the same (Asn-Asn-Phe-Ser-Asp-Cys-Phe-Trp-Lys-Tyr-Cys-Val) and this amino acid sequence is identical to that of urotensin II from the dogfish and skate. Consistent with previous morphological studies indicating that the Agnatha lack a caudal neurosecretory system, urotensin II was not detected in an extract of P. marinus spinal cord. The data suggest that the urotensin II may have functioned in the earliest vertebrates as a neurotransmitter/neuromodulator in the central nervous system rather than as a neurohormone of the caudal neurosecretory system. Urotensin II was also isolated from an extract of the spinal cord of a chondrostean fish, the paddlefish (Polyodon spathula). The primary structure of the paddlefish urotensin II (Gly-Ser-Thr-Ser-Glu-Cys-Phe-Trp-Lys-Tyr-Cys-Val) is the same as that of another chondrostean, the sturgeon (Acipenser ruthenus). The study provides further evidence for a widespread distribution of urotensin II in vertebrate species and suggests that the primary structure of the peptide is better conserved in these phylogenetically ancient fish than in teleosts. (C) 1995 Academic Press, Inc.

A PEPTIDE FROM THE CAUDAL NEUROSECRETORY-SYSTEM OF THE DOGFISH SCYLIORHINUS-CANICULA THAT IS STRUCTURALLY RELATED TO UROTENSIN-I

Using reversed-phase HPLC in combination with a radioimmunoassay for ovine corticotropin-releasing hormone (CRH), a peptide with CRH-like immunoreactivity was isolated in pure form from an extract of the caudal spinal cord region of the spotted dogfish, Scyliorhinus canicula. The primary structure of the peptide was established as Pro-Ala-Glu-Thr-Pro-Asn-Ser-Leu-Asp-Leu(10)-Thr-Phe-His-Leu-Leu-Arg-Glu-Met-Ile-Glu(20)-Ile-Ala-Lys-His-Glu-Asn-Gln-Gln-Met-Gln(30)-Ala-Asp-Ser-Asn-Arg-Arg-Ile-Met-Asp-Thr(40)-Ile . NH2. This amino acid sequence shows moderate structural similarity to Catostomus urotensin I (51%) and to human CRH (56%). The data provide, therefore, chemical evidence to support the conclusions of earlier immunohistochemical studies that the diffuse caudal neurosecretory system of elasmobranchs produces a peptide that is immunochemically related to teleost urotensin I peptides. However, the primary structure of urotensin I has been poorly conserved during evolution. (C) 1995 Academic Press, Inc.

Deficiencies of folate and vitamin B-6 exert distinct effects on homocysteine, serine, and methionine kinetics

Folate and vitamin B-6 act in generating methyl groups for homocysteine remethylation, but the kinetic effects of folate or vitamin B-6 deficiency are not known. We used an intravenous primed, constant infusion of stable isotope-labeled serine, methionine, and leucine to investigate one-carbon metabolism in healthy control (n = 5), folate-deficient (n = 4), and vitamin B-6-deficient (n = 5) human subjects. The plasma homocysteine concentration in folate-deficient subjects [15.9 +/-2.1 (SD) mu mol/l] was approximately two times that of control (7.4 +/-1.7 mmol/l) and vitamin B-6-deficient (7.7 +/-2.1 mmol/l) subjects. The rate of methionine synthesis by homocysteine remethylation was depressed (P = 0.027) in folate deficiency but not in vitamin B-6 deficiency. For all subjects, the homocysteine remethylation rate was not significantly associated with plasma homocysteine concentration (r = -0.44, P = 0.12). The fractional synthesis rate of homocysteine from methionine was positively correlated with plasma homocysteine concentration (r = 0.60, P = 0.031), and a model incorporating both homocysteine remethylation and synthesis rates closely predicted plasma homocysteine levels (r = 0.85, P = 0.0015). Rates of homocysteine remethylation and serine synthesis were inversely correlated (r = -0.89, P < 0.001). These studies demonstrate distinctly different metabolic consequences of vitamin B-6 and folate deficiencies.

The role of lipids and protein kinase Cs in the pathogenesis of diabetic retinopathy

Diabetic retinopathy is one of the most common complications of diabetes and is a major cause of new blindness in the working-age population of developed countries. While the exact pathogenic basis of this condition remains ill defined, it is clear that hyperglycaemia is a critical factor in its aetiology. Protein kinase C (PKC) activation is one of the sequelae of hyperglycaemia and it is thought to play an important role in the development of diabetic complications. This review questions the currently held dogma that PKC stimulation in diabetes is solely mediated through the overproduction of palmitate and oleate enriched diacylglycerols. Blood glucose concentrations are closely tracked by changes in the levels of free fatty acids and these, in addition to oxidative stress, may account for the aberrant activation of PKCs in diabetes. Little is known about why PKCs fail to downregulate in diabetes and efforts should be directed towards acquiring such information. Considerable evidence implicates the PKCbeta isoform in the pathogenesis of diabetic retinopathy, but other isoforms may also be of relevance. In addition to PKCs, it is evident that novel diacyglycerol-activated non-kinase receptors could also play a role in the development of diabetic complications. Therapeutic agents have been developed to inhibit specific PKC isoforms and PKCbeta antagonists are currently undergoing clinical trials to test their toxicity and efficacy in suppressing diabetic complications. The likely impact of these drugs in the treatment of diabetic patients is considered.

Association analysis of proopiomelanocortin (POMC) haplotypes in type 1 diabetes in a UK population

Aim

To assess the association of POMC haplotype-tagged single nucleotide polymorphisms (htSNPs) with the development of type 1 diabetes (T1D) in a Caucasian population.

Methods

All exons, intron 1, and approximately 6-kb upstream and 3-kb downstream of the POMC gene were bidirectionally resequenced to identify DNA polymorphisms in 30 individuals. Allele frequencies were determined (60 chromosomes) and efficient htSNPs were selected using the htSNP2 programme. Genotyping was performed in 390 cases, 339 controls and 245 T1D parent-offspring trios, using Taqman, Sequenom and direct-sequencing technologies.

Results

Thirteen polymorphisms (two novel) with a minor allele frequency greater than 1% were identified. Six POMC htSNPs (rs3754863 G>A, ss161151662 A>G, rs3754860 C>T, rs1009388 G>C, rs3769671 A>C, rs1042571 G>A) were identified. Allele and haplotype frequencies were similar between case and control groups (P>0.60 by permutation test), and assessment of allele transmission distortion from informative parents to affected offspring also failed to find any association. Stratification of these analyses for age-at-onset and HLA-DR risk group (DR3/DR4) revealed no significant associations. A haplotype block of 9.86-kb from rs3754863 to rs1042571 was identified, encompassing the POMC gene. Comparison of haplotype frequencies identified the GGCGAG haplotype as protective against T1D in 12.9% of cases vs. 18.3% of controls: ?2=8.18, Pc=0.03 by permutation test.

Conclusion

The POMC SNP haplotype GGCGAG may have a protective effect against T1D in the UK population. However, this finding needs to be replicated, and the cellular and molecular processes influenced by this POMC haplotype determined to fully appreciate its impact.

Trends in childhood type 1 diabetes incidence in Europe during 1989-2008: evidence of non-uniformity over time in rates of increase

AIMS/HYPOTHESIS:

The aim of the study was to describe 20-year incidence trends for childhood type 1 diabetes in 23 EURODIAB centres and compare rates of increase in the first (1989-1998) and second (1999-2008) halves of the period.

METHODS:

All registers operate in geographically defined regions and are based on a clinical diagnosis. Completeness of registration is assessed by capture-recapture methodology. Twenty-three centres in 19 countries registered 49,969 new cases of type 1 diabetes in individuals diagnosed before their 15th birthday during the period studied.

RESULTS:

Ascertainment exceeded 90% in most registers. During the 20-year period, all but one register showed statistically significant changes in incidence, with rates universally increasing. When estimated separately for the first and second halves of the period, the median rates of increase were similar: 3.4% per annum and 3.3% per annum, respectively. However, rates of increase differed significantly between the first half and the second half for nine of the 21 registers with adequate coverage of both periods; five registers showed significantly higher rates of increase in the first half, and four significantly higher rates in the second half.

CONCLUSIONS/INTERPRETATION:

The incidence rate of childhood type 1 diabetes continues to rise across Europe by an average of approximately 3-4% per annum, but the increase is not necessarily uniform, showing periods of less rapid and more rapid increase in incidence in some registers. This pattern of change suggests that important risk exposures differ over time in different European countries. Further time trend analysis and comparison of the patterns in defined regions is warranted.

The structures of four bombesins and their cloned precursor-encoding cDNAs from acid-solvated skin secretion of the European yellow-bellied toad, Bombina variegata

Four different bombesins (bombesin, His(6)-bombesin, Phe(13)-bombesin and Asp(2)-, Phe(4)-SAP-bombesin) have been identified by a systematic sequencing study of peptides in reverse phase HPLC fractions of the skin secretion of the European yellow-bellied toad, Bombina variegata, that had been solvated in 0.1% (v/v) aqueous trifluoroacetic acid (TFA) and stored frozen at -20°C for 12 years. By using a 3'- and 5'-RACE PCR strategy, the corresponding biosynthetic precursor-encoding cDNAs of all four peptides were cloned from a cDNA library made from the same long-term frozen, acid-solvated skin secretion sample following thawing and lyophilization. Canonical bombesin and His(6)-bombesin are classical bombesin sub-family members, whereas Phe(13)-bombesin and Asp(2)-, Phe(4)-SAP-bombesin, belong to the litorin/ranatensin sub-family of bombesin-like peptides (BLPs). Assignment of these peptides to respective sub-families, was based upon both their primary structural similarities and their comparative pharmacological activities. An interesting observation in this study, was that the nucleotide sequences of the open-reading frames of cloned cDNAs encoding bombesin and its His(6)-substituted analog, were identical except for a single base that was responsible for the change observed at the position 6 residue in the mature peptide from Asn to His. In contrast, the precursor cDNA nucleotide sequences encoding the Phe(13)-bombesins, exhibited 53 base differences. The pharmacological activities of synthetic replicates of each bombesin were compared using two different mammalian smooth muscle preparations and all four peptides were found to be active. However, there were significant differences in their relative potencies.

The geriatric minimum data set for clinical trials (GMDS)

To overcome the weak evidence base coming from often poor and insufficient clinical research in older people, a minimum data set to achieve harmonisation is highly advisable. This will lead to uniform nomenclature and to the standardisation of the assessment tools. Our primary objective was to develop a Geriatric Minimum Data Set (GMDS) for clinical research.