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Mark I McCarthy

Publications and source records attributed to Mark I McCarthy.

At least 55 records · Page 3Linked to original sources
PubMed2004

Variation at the insulin gene VNTR (variable number tandem repeat) polymorphism and early growth: studies in a large Finnish birth cohort.

Variation at the insulin gene (INS-)VNTR (variable number of tandem repeats) minisatellite polymorphism has been reported to be associated with both early growth and adult metabolic phenotypes. However, the samples studied have been small and the relationship between INS-VNTR variation and parameters of early growth inconsistent, with four previous studies producing conflicting results. We have studied the relationship between INS-VNTR class (measured by genotyping the nearby -23HphI variant with which it is in tight linkage disequilibrium) and early growth in 5,646 members of the Northern Finnish Birth Cohort of 1966. Comparing class III homozygotes with other genotypes using multivariate linear regression analysis, we found no significant associations with any early growth measure (birth weight, birth length, ponderal index, and head circumference at 1 year), even after stratifying subjects by growth trajectory during infancy and/or birth order. For example, among infants with limited postnatal growth realignment (n = 2,470), class III/III infants were no heavier at birth (difference [+/-SE] in the means [fully adjusted], 58 +/- 51 g; P = 0.26) than class I/- infants. No significant associations were detected following reanalysis with an additive model (for example, for birth weight, beta = 20 g [95% CI -3 to 44], P = 0.09). Studies of this large population-based cohort have failed to generate convincing evidence that INS-VNTR variation influences early growth.

Birth Order↗
PubMed2003

A meta-analysis of four European genome screens (GIFT Consortium) shows evidence for a novel region on chromosome 17p11.2-q22 linked to type 2 diabetes.

Positional cloning is expected to identify novel susceptibility genes underlying complex traits, but replication of genome-wide linkage scan findings has proven erratic. To improve our ability to detect and prioritize chromosomal regions containing type 2 diabetes susceptibility genes, the GIFT consortium has implemented a meta-analysis of four scans conducted in European samples. These included the Botnia I and Botnia II scans, with respectively 58 and 353 pedigrees from Finland and Sweden, the Warren 2 scan performed in 573 multiplex sibships from the UK, and a scan of 143 families from France. The meta-analysis was implemented using the genome-search analysis method (GSMA), an exploratory data analysis technique which is robust across study designs. The analysis provided evidence for linkage of type 2 diabetes to six regions, with the strongest evidence on chromosome 17p11.2-q22 (P=0.0016), followed by 2p22.1-p13.2 (P=0.027), 1p13.1-q22 (P=0.028), 12q21.1-q24.12 (P=0.029), 6q21-q24.1 (P=0.033) and 16p12.3-q11.2 (P=0.033). Linkage analysis of the pooled raw genotype data generated maximum LOD scores in the same regions as identified by GSMA. Altogether, our results have indicated that GSMA is a valuable tool to identify chromosomal regions of interest and that accumulating evidence for linkage from small peaks detected across several samples may be more important than getting a high peak in a single sample. This meta-analysis has led to identification of a novel region on chromosome 17 linked to type 2 diabetes; this region has not been highlighted in any published scan to date but on the basis of these data justifies further exploration.

Chromosome Mapping↗
PubMed2003

Estimation and testing of parent-of-origin effects for quantitative traits.

Recent progress in developing family-based association methods has extended their use to the analysis of quantitative traits in the offspring and to the estimation, for dichotomous traits, of the relative contribution of genetic and environmental mechanisms for parent-of-origin effects. However, many traits of interest are not naturally measured on a binary scale yet are suspected or known to be influenced by imprinted genes, and there is consequent interest in seeking evidence for parent-of-origin effects at these loci. Here we show how simple linear models can be used to estimate these parent-of-origin effects for a broad class of phenotypes; in particular, normally distributed quantitative traits are easily dealt with.

Female↗
PubMed2003

Growing evidence for diabetes susceptibility genes from genome scan data.

Genome-wide scans for linkage have provided one of the dominant approaches adopted by researchers in their efforts to identify genes responsible for the inherited component of type 2 diabetes susceptibility. Around 20 genome scans have now been completed, in a wide variety of populations. Integration of data from these diverse scans has proven far from trivial, but the contours of genome-wide linkage topography are steadily emerging from the fog of data. Identification of the calpain-10 gene as the probable basis for the chromosome 2q linkage seen in Mexican Americans has provided validation of this positional cloning approach. This report provides an update on recent type 2 diabetes genome scan data, focusing on several chromosomal regions where the evidence for linkage has considerably strengthened in the past year. The current and future value of genome-wide linkage information in the search for type 2 diabetes susceptibility effects is also discussed.

Diabetes Mellitus, Type 2↗
PubMed2003

Insulin resistance and beta-cell dysfunction in normoglycaemic European women with a history of gestational diabetes.

OBJECTIVE: Women with previous gestational diabetes (GDM) are at increased risk of subsequent type 2 diabetes. To characterize early metabolic abnormalities associated with this increased risk, we studied normoglycaemic women with a history of GDM. PATIENTS AND MEASUREMENTS: We performed an insulin-modified, frequently sampled intravenous glucose tolerance test (FSIVGTT) in 34 normoglycaemic European women with previous GDM and 44 European control women, deriving measures of insulin sensitivity, glucose effectiveness, glucose disappearance rate and acute insulin response to glucose. RESULTS: Post-GDM women were more obese than controls [body mass index (BMI), geometric mean (95% confidence interval); 25.3 kg/m2 (23.8-27.1 kg/m2) vs. 23.1 kg/m2 (21.9-24.3 kg/m2), P = 0.03]. Evidence of insulin resistance was provided by their lower insulin sensitivity as measured by FSIVGTT [0.6 x 10-4/min/pmol/l (0.3-1.2 x 10-4/min/pmol/l) vs. 1.5 x 10-4/min/pmol/l (1.2-1.8 x 10-4/min/pmol/l), P = 0.01] and by homeostatic model assessment [72% (49-107%) vs. 153% (113-206%), P = 0.004]; and by their higher fasting triglycerides [1.0 mmol/l (0.7-1.5 mmol/l) vs. 0.7 mmol/l (0.6-0.8 mmol/l), P = 0.001]. Though there was no difference between groups in fasting NEFA levels, acute NEFA suppression was diminished in the post-GDM group (P = 0.01). Concomitant beta-cell dysfunction in the post-GDM women was revealed by their lower disposition index [0.05/min (0.02-0.10/min) vs. 0.11/min (0.09-0.14/min), P = 0.02] compared to controls. The differences in insulin sensitivity, but not those of beta-cell function, were partly, though not completely, attributable to differences in regional and total adiposity. CONCLUSIONS: European normoglycaemic women with previous GDM display both glucoregulatory and antilipolytic insulin resistance, reduced beta-cell function and dyslipidaemia. These metabolic abnormalities are likely to contribute to their increased risk of future type 2 diabetes.

Adult↗
PubMed2003

eVOC: a controlled vocabulary for unifying gene expression data.

Expression data contribute significantly to the biological value of the sequenced human genome, providing extensive information about gene structure and the pattern of gene expression. ESTs, together with SAGE libraries and microarray experiment information, provide a broad and rich view of the transcriptome. However, it is difficult to perform large-scale expression mining of the data generated by these diverse experimental approaches. Not only is the data stored in disparate locations, but there is frequent ambiguity in the meaning of terms used to describe the source of the material used in the experiment. Untangling semantic differences between the data provided by different resources is therefore largely reliant on the domain knowledge of a human expert. We present here eVOC, a system which associates labelled target cDNAs for microarray experiments, or cDNA libraries and their associated transcripts with controlled terms in a set of hierarchical vocabularies. eVOC consists of four orthogonal controlled vocabularies suitable for describing the domains of human gene expression data including Anatomical System, Cell Type, Pathology and Developmental Stage. We have curated and annotated 7016 cDNA libraries represented in dbEST, as well as 104 SAGE libraries,with expression information,and provide this as an integrated, public resource that allows the linking of transcripts and libraries with expression terms. Both the vocabularies and the vocabulary-annotated libraries can be retrieved from http://www.sanbi.ac.za/evoc/. Several groups are involved in developing this resource with the aim of unifying transcript expression information.

Animals↗
PubMed2003

Hormonal profile of women with self-reported symptoms of oligomenorrhea and/or hirsutism: Northern Finland birth cohort 1966 study.

The hormonal profiles of nested female patients (n = 500) with self-reported symptoms typical of polycystic ovary syndrome (PCOS), oligomenorrhea, and/or hirsutism and their randomly selected controls (n = 1026) at the age of 31 yr were analyzed in a general population-based Northern Finland birth cohort 1966 to find out whether the symptomatic women also have the endocrine characteristics of PCOS and could be detected in a general population using simple questions. Higher medians of serum testosterone (T) (2.10 vs. 1.90 nmol/liter, P < 0.001), LH (5.40 vs. 4.85 U/liter, P = 0.005), insulin (53.8 vs. 51.66 pmol/liter, P = 0.040), and free androgen index (FAI) (4.01 vs. 3.03, P < 0.001) and lower glucose/insulin ratio (91.1 x 10(8) vs. 94.9 x 10(8), P = 0.048) and SHBG (52.4 vs. 60.7 nmol/liter, P < 0.001) were observed among the cases, but no difference was observed in cortisol and glucose levels between the cases and controls. Of all the women in the cohort, 10.2% reported only oligomenorrhea and had biochemical findings similar to the whole case group. Those who reported only hirsutism (10.4%) were in between the case and control groups according to biochemical findings. The subjects who reported both oligomenorrhea and hirsutism (3.4%) had the highest T, LH, FAI, insulin, and glucose and the lowest SHBG and glucose/insulin ratio, compared with the case group and the groups with either symptom only indicating a dose-response manner in typical endocrine profile of PCOS by adding up symptoms. The levels of T and FAI were higher and SHBG lower in groups with overweight or obesity both at 14 and 31 yr, compared with groups with normal weight at 14 yr and overweight or obesity at 31 yr. In the group with normal weight at 14 and 31 yr and the group with overweight or obesity at 14 yr but normal weight at 31 yr, the levels of T and FAI were lowest and SHBG highest. T and FAI were higher and SHBG lower among the cases than the controls in groups stratified by weight development from adolescence to adulthood. In conclusion, this longitudinal study of a large, stable population indicates that women with self-reported symptoms of hirsutism and/or oligomenorrhea show endocrine characteristics of PCOS and can be detected in a general population using simple questions. These symptoms are markers of the underlying metabolic alterations possibly associated with increased health risks in later life.

Adult↗
PubMed2003

Prevalence of polycystic ovaries in women with androgenic alopecia.

OBJECTIVE: Although androgenic alopecia is recognised to be a symptom of polycystic ovary syndrome (PCOS), it is not known whether polycystic ovaries (PCO) and associated endocrine abnormalities are present in patients who present with alopecia as a primary complaint. We therefore set out to determine the strength of the association between androgenic alopecia and PCO. We examined the prevalence of ultrasound-based polycystic ovarian morphology and associated clinical and biochemical features in a large multiethnic group of women whose presenting complaint was of alopecia, and in a control group. SUBJECTS AND METHODS: We studied 89 women of mixed ethnic origin with androgenic alopecia and compared them to 73 control women. A detailed history was taken, anthropometry was performed and assessment of body-hair distribution was made. The presence of PCO was established by pelvic ultrasound scan. Serum gonadotrophins, testosterone, androstenedione, dihydrotestosterone and sex hormone binding globulin concentrations were measured. RESULTS: Women with alopecia had a higher prevalence of PCO and hirsutism than the control population (PCO: 67% vs 27%, P<0.00001; hirsutism: 21% vs 4%, P=0.003). Women with alopecia (with or without PCO) had higher testosterone, androstenedione and free androgen index than controls, even though few had frankly abnormal androgens. CONCLUSIONS: These findings confirm an association between androgenic alopecia and PCO, and other symptoms of hyperandrogenaemia. Thus most women who present with androgenic alopecia as their primary complaint also have PCO and have indices of abnormal androgen production. Since PCO is a well known risk factor for development of type 2 diabetes, this association has important implications for long-term management.

Adult↗
PubMed2003

Large-scale association studies of variants in genes encoding the pancreatic beta-cell KATP channel subunits Kir6.2 (KCNJ11) and SUR1 (ABCC8) confirm that the KCNJ11 E23K variant is associated with type 2 diabetes.

The genes ABCC8 and KCNJ11, which encode the subunits sulfonylurea receptor 1 (SUR1) and inwardly rectifying potassium channel (Kir6.2) of the beta-cell ATP-sensitive potassium (K(ATP)) channel, control insulin secretion. Common polymorphisms in these genes (ABCC8 exon 16-3t/c, exon 18 T/C, KCNJ11 E23K) have been variably associated with type 2 diabetes, but no large ( approximately 2,000 subjects) case-control studies have been performed. We evaluated the role of these three variants by studying 2,486 U.K. subjects: 854 with type 2 diabetes, 1,182 population control subjects, and 150 parent-offspring type 2 diabetic trios. The E23K allele was associated with diabetes in the case-control study (odds ratio [OR] 1.18 [95% CI 1.04-1.34], P = 0.01) but did not show familial association with diabetes. Neither the exon 16 nor the exon 18 ABCC8 variants were associated with diabetes (1.04 [0.91-1.18], P = 0.57; 0.93 [0.71-1.23], P = 0.63, respectively). Meta-analysis of all case-control data showed that the E23K allele was associated with type 2 diabetes (K allele OR 1.23 [1.12-1.36], P = 0.000015; KK genotype 1.65 [1.34-2.02], P = 0.000002); but the ABCC8 variants were not associated. Our results confirm that E23K increases risk of type 2 diabetes and show that large-scale association studies are important for the identification of diabetes susceptibility alleles.

ATP-Binding Cassette Transporters↗
PubMed2003

Genetic variation in the small heterodimer partner gene and young-onset type 2 diabetes, obesity, and birth weight in U.K. subjects.

The orphan receptor small heterodimer partner (SHP, NR0B2) modulates the transcription activity of the MODY1 gene HNF4a. Mutations in SHP were found in 7% of Japanese obese young-onset type 2 diabetic patients and were associated with moderate obesity and increased birth weight. We investigated SHP in 1927 U.K. subjects, examining relationships with type 2 diabetes, obesity, and birth weight. Sequencing of the coding region of SHP in 122 obese, young-onset type 2 diabetic patients detected the polymorphism G171A. The polymorphism was not associated with diabetes in case control or familial association studies. The A allele (frequency 0.07) was not associated with obesity in type 2 diabetic subjects (n = 348), their parents (n = 272), or young nondiabetic adults (n = 925). However, the rare (<1%) AA homozygotes had a raised BMI in each cohort; this was significant when all cohorts were combined (Z score = 0.67 AA vs. -0.05 G/x, P = 0.02). There was no association with corrected birth weight in 382 normal babies, but the only AA baby was 4,069 g. Our study suggests that genetic variation in SHP is unlikely to be common in the predisposition to diabetes, obesity, or increased birth weight in U.K. Caucasians.

Adolescent↗
PubMed2003

Association and haplotype analysis of the insulin-degrading enzyme (IDE) gene, a strong positional and biological candidate for type 2 diabetes susceptibility.

The gene for insulin-degrading enzyme (IDE) represents a strong positional and biological candidate for type 2 diabetes susceptibility. IDE maps to chromosome 10q23.3, a region linked to diabetes in several populations; the rat homolog has been directly implicated in diabetes susceptibility; and known functions of IDE support an important role in glucose homeostasis. We sought evidence for association between IDE variation and diabetes by mutation screening, defining local haplotype structure, and genotyping variants delineating common haplotypic diversity. An initial case-control analysis (628 diabetic probands from multiplex sibships and 604 control subjects) found no haplotypic associations, although one variant (IDE2, -179T-->C) showed modest association with diabetes (odds ratio [OR]1.25, P = 0.03). Linkage partitioning analyses failed to support this association, but provided borderline evidence for a different variant (IDE10, IVS20-405A-->G) (P = 0.06). Neither variant was associated with diabetes when replication was sought in 377 early onset diabetic subjects and 825 control subjects, though combined analysis of all typed cohorts indicated a nominally significant effect at IDE2 (OR 1.21 [1.04-1.40], P = 0.013). In the absence of convincing support for this association from linkage partitioning or analyses of continuous measures of glycemia, we conclude that analysis of over 2,400 samples provides no compelling evidence that variation in IDE contributes to diabetes susceptibility in humans.

Blood Glucose↗
PubMed2003

Young-onset type 2 diabetes families are the major contributors to genetic loci in the Diabetes UK Warren 2 genome scan and identify putative novel loci on chromosomes 8q21, 21q22, and 22q11.

A young onset of type 2 diabetes is likely to result, in part, from greater genetic susceptibility. Young-onset families may therefore represent a group in which genes are more easily detectable by linkage. To test this hypothesis, we conducted age at diagnosis (AAD) stratified linkage analyses in the Diabetes UK Warren 2 sibpairs. In the previously published unstratified analysis, evidence for linkage (logarithm of odds [LOD] >1.18) was found at seven loci. The LOD scores at these seven loci were higher in the 245 families with AAD <55 years (L55) compared with the 328 families with AAD >55 years (G55). Five of these seven loci (1q24-25, 5q13, 8p21-22, 8q24.2, and 10q23.2) had LOD scores >1.18 in the L55 subset but only one (8p21-22) did in the G55 subset. Two additional loci (8q21.13 and 21q22.2) showed evidence for linkage in the L55 subset alone. Another locus (22q11) showed evidence for linkage in a subset of families with AAD <45 years. Using a locus-counting approach, the L55 subset had significantly more loci (P approximately 0.01) than expected under the null hypothesis of no linkage across the LOD score range 0.59-3.0. In contrast, the G55 subset contained no more susceptibility loci than that expected by chance. In conclusion, young-onset families provide both disproportionate evidence for linkage to known loci and evidence for additional novel loci. Our data confirm our hypothesis that families segregating young-onset type 2 diabetes represent a more powerful resource for defining susceptibility genes by linkage.

Age of Onset↗
PubMed2002

Evaluating the results of genomewide linkage scans of complex traits by locus counting.

The evaluation of results from primary genomewide linkage scans of complex human traits remains an area of importance and considerable debate. Apart from the usual assessment of statistical significance by use of asymptotic and empirical calculations, an additional means of evaluation--based on counting the number of distinct regions showing evidence of linkage--is possible. We have explored the characteristics of such a locus-counting method over a range of experimental conditions typically encountered during genomewide scans for complex trait loci. Under the null hypothesis, factors that have an impact on the informativeness of the data--such as map density, availability of parental data, and completeness of genotyping--are seen to markedly influence the number of regions of excess allele sharing and the empirically derived genomewide significance of the associated LOD score thresholds. In some circumstances, the expected number of regions is less than one-quarter of that predicted under the assumption of a dense map and complete extraction of inheritance information. We have applied this method to a previously analyzed data set--the Warren 2 genome scan for type 2-diabetes susceptibility--and demonstrate that more regions showing evidence for linkage were observed in the primary genome scan than would be expected by chance, across the whole range of LOD scores, even though no single linkage result achieved empirical genomewide statistical significance. Locus counting may be useful in assessing the results from genome scans for complex traits in general, especially because relatively few scans generate evidence for linkage reaching genomewide significance by dense-map criteria. By taking account of the effects of reduced data informativeness on the expected number of regions showing evidence for linkage, a more meaningful, and less conservative, evaluation of the results from such linkage studies is possible.

Computer Simulation↗
PubMed2002

Elevation of soluble E-selectin levels following gestational diabetes is restricted to women with persistent abnormalities of glucose regulation.

OBJECTIVE: Increased levels of the soluble adhesion molecule sE-selectin have been reported in normoglycaemic women with previous gestational diabetes but not in other groups at increased risk of future type 2 diabetes. To explore the basis for these discrepant findings, we studied the relationship between sE-selectin and glucose regulation in a large group of women with previous gestational diabetes. DESIGN: Comparison of sE-selectin levels between a study cohort ascertained on the basis of recent gestational diabetes and suitable control subjects. PATIENTS: One hundred and forty women with recent gestational diabetes (104 European, 20 South Asian and 16 Afro-Caribbean) and 125 normoglycaemic control women (90 European, 19 South Asian and 16 Afro-Caribbean). MEASUREMENTS: sE-selectin, fasting lipids, insulin and current glucose regulation status. RESULTS: There was no overall difference in sE-selectin levels between women with a history of gestational diabetes and control women among the 3 ethnic groups. European post-GDM women with abnormal glucose regulation postpartum (n = 30) had higher sE-selectin than control women (67 (54-91) ng/ml vs. 57 (43-75) ng/ml, P = 0.049). There was no difference in sE-selectin between normoglycaemic European women with a history of gestational diabetes (n = 74) and control women, even though the former displayed metabolic abnormalities predictive of diabetes. In those European post-GDM women with normal glucose regulation postpartum, sE-selectin levels were negatively correlated with time since delivery (r = -0.25, P = 0.04), suggesting that the previously described elevation of sE-selectin following GDM pregnancies slowly resolves postpartum. There was no correlation between sE-selectin levels and features of insulin resistance. CONCLUSIONS: In contrast to previous findings, this larger study does not support a role for sE-selectin as a marker, independent of prevailing glucose levels, of early metabolic abnormalities or future diabetes risk in women with previous gestational diabetes.

Adult↗
PubMed2002

Genetic approaches to the molecular understanding of type 2 diabetes.

The appreciation that individual susceptibility to type 2 diabetes (T2D) and related components of the dysmetabolic syndrome has a strong inherited component provides a coherent framework within which to develop a molecular understanding of the pathogenesis of T2D. This review focuses on the main approaches currently adopted by researchers seeking to identify the inherited basis of T2D and the present state of our knowledge. One central theme that emerges is that progress in defining the genetic basis of the common, multifactorial forms of T2D is hindered by etiological heterogeneity: T2D is likely to represent the final common pathway of diverse interacting primary disturbances. Such heterogeneity equally compromises efforts to understand the basis for T2D by use of other approaches, such as cellular biochemistry and classical physiology. Analyses that seek to ally sophisticated physiological characterization with measures of genomic variation are likely to provide powerful tools for redressing the loss of power associated with such heterogeneity.

Diabetes Mellitus, Type 2↗
PubMed2002

Variation within the type 2 diabetes susceptibility gene calpain-10 and polycystic ovary syndrome.

Variation within the calpain-10 gene (CAPN10) has been proposed to account for linkage to type 2 diabetes on chromosome 2q in Mexican-Americans, and associations with diabetes have been reported in several other populations. Given the epidemiological, physiological, and genetic overlap between type 2 diabetes and polycystic ovary syndrome (PCOS), CAPN10 represents a strong candidate gene for a role in PCOS susceptibility. Using both family based and case-control association resources (146 parent-offspring trios; 185 additional PCOS cases; 525 control subjects, all of European ancestry), we sought association between CAPN10 variation and PCOS, focusing on four single nucleotide polymorphism (SNP) variants (SNP-44, SNP-43; SNP-19; SNP-63). On single-locus transmission disequilibrium analysis in the 146 trios, there was nominal evidence (P = 0.03) of excess transmission of the more common allele at SNP-63. This association was not, however, replicated in the case-control analysis. No other significant associations were observed at the single-locus or haplotype level in either the transmission-disequilibrium or case-control analyses. The relative risk for the high-risk diabetes susceptibility 112/121 genotype (SNPs 43-19-63) was 0.84 (95% confidence intervals, 0.40-1.71). No associations were seen with intermediate traits of relevance to diabetes and PCOS pathogenesis. We have found no evidence from these analyses that CAPN10 gene variation influences susceptibility to PCOS.

Adult↗