Maturity-onset of the young (MODY) is a clinically heterogeneous form of diabetes characterized by an autosomal-dominant mode of inheritance, an onset before the age of 25 years, and a primary defect ...in the pancreatic beta-cell function. Approximately 30% of MODY families remain genetically unexplained (MODY-X). Here, we aimed to use whole-exome sequencing (WES) in a four-generation MODY-X family to identify a new susceptibility gene for MODY.
WES (Agilent-SureSelect capture/Illumina-GAIIx sequencing) was performed in three affected and one non-affected relatives in the MODY-X family. We then performed a high-throughput multiplex genotyping (Illumina-GoldenGate assay) of the putative causal mutations in the whole family and in 406 controls. A linkage analysis was also carried out.
By focusing on variants of interest (i.e. gains of stop codon, frameshift, non-synonymous and splice-site variants not reported in dbSNP130) present in the three affected relatives and not present in the control, we found 69 mutations. However, as WES was not uniform between samples, a total of 324 mutations had to be assessed in the whole family and in controls. Only one mutation (p.Glu227Lys in KCNJ11) co-segregated with diabetes in the family (with a LOD-score of 3.68). No KCNJ11 mutation was found in 25 other MODY-X unrelated subjects.
Beyond neonatal diabetes mellitus (NDM), KCNJ11 is also a MODY gene ('MODY13'), confirming the wide spectrum of diabetes related phenotypes due to mutations in NDM genes (i.e. KCNJ11, ABCC8 and INS). Therefore, the molecular diagnosis of MODY should include KCNJ11 as affected carriers can be ideally treated with oral sulfonylureas.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Molecular typing based on 12 loci containing variable numbers of tandem repeats of mycobacterial interspersed repetitive units (MIRU-VNTRs) has been adopted in combination with spoligotyping as the ...basis for large-scale, high-throughput genotyping of Mycobacterium tuberculosis. However, even the combination of these two methods is still less discriminatory than IS6110 fingerprinting. Here, we define an optimized set of MIRU-VNTR loci with a significantly higher discriminatory power. The resolution and the stability/robustness of 29 loci were analyzed, using a total of 824 tubercle bacillus isolates, including representatives of the main lineages identified worldwide so far. Five loci were excluded for lack of robustness and/or stability in serial isolates or isolates from epidemiologically linked patients. The use of the 24 remaining loci increased the number of types by 40%--and by 23% in combination with spoligotyping--among isolates from cosmopolitan origins, compared to those obtained with the original set of 12 loci. Consequently, the clustering rate was decreased by fourfold--by threefold in combination with spoligotyping--under the same conditions. A discriminatory subset of 15 loci with the highest evolutionary rates was then defined that concentrated 96% of the total resolution obtained with the full 24-locus set. Its predictive value for evaluating M. tuberculosis transmission was found to be equal to that of IS6110 restriction fragment length polymorphism typing, as shown in a companion population-based study. This 15-locus system is therefore proposed as the new standard for routine epidemiological discrimination of M. tuberculosis isolates and the 24-locus system as a high-resolution tool for phylogenetic studies.
Prevalence of Melanocortin-4 Receptor Deficiency in Europeans and Their Age-Dependent Penetrance in Multigenerational Pedigrees
Fanny Stutzmann 1 ,
Karen Tan 2 ,
Vincent Vatin 1 ,
Christian Dina 1 ,
...Béatrice Jouret 3 ,
Jean Tichet 4 ,
Beverley Balkau 5 ,
Natascha Potoczna 6 ,
Fritz Horber 6 ,
Stephen O'Rahilly 2 ,
I. Sadaf Farooqi 2 ,
Philippe Froguel 1 7 and
David Meyre 1
1 Centre National de la Recherche Scientifique-8090, Institute of Biology, Pasteur Institute, Lille, France
2 University of Cambridge Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge,
U.K
3 Institut National de la Santé et de la Recherche Médicale U563, Children's Hospital, Toulouse, France
4 Institut inter Régional pour la Santé, La Riche, France
5 Institut National de la Santé et de la Recherche Médicale U780-IFR69, Villejuif, Université Paris-Sud, Orsay, France
6 Klinik Lindberg, Winterthur, and University of Berne, Berne, Switzerland
7 Department of Genomic Medicine, Hammersmith Hospital, Imperial College London, London, U.K
Corresponding author: Philippe Froguel, p.froguel{at}imperial.ac.uk
Abstract
OBJECTIVE— Melanocortin-4 receptor (MC4R) deficiency is the most frequent genetic cause of obesity. However, there is uncertainty regarding
the degree of penetrance of this condition, and the putative impact of the environment on the development of obesity in MC4R mutation carriers is unknown.
RESEARCH DESIGN AND METHODS— We determined the MC4R sequence in 2,257 obese individuals and 2,677 nonobese control subjects of European origin and established the likely functional
impact of all variants detected. We then included relatives of probands carriers and studied 25 pedigrees, including 97 carriers
and 94 noncarriers from three generations.
RESULTS— Of the MC4R nonsynonymous mutations found in obese subjects, 68% resulted in a loss of function in vitro. They were found in 1.72% of
obese versus 0.15% of nonobesed subjects ( P = 6.9 × 10 −10 ). Among the families, abnormal eating behavior was more frequent in both MC4R-deficient children and adults than in noncarriers.
Although BMI was inversely associated with educational status in noncarrier adults, no such relationship was seen in MC4R mutation carriers. We observed a generational effect, with a penetrance of 40% in MC4R-deficient adults aged >52 years, 60%
in 18- to 52-year-old adults, and 79% in children. The longitudinal study of adult carriers showed an increasing age-dependent
penetrance (37% at 20 years versus 60% at >40 years).
CONCLUSIONS— We have established a robust estimate of age-related penetrance for MC4R deficiency and demonstrated a generational effect
on penetrance, which may relate to the development of an “obesogenic” environment. It remains to be seen whether appropriate
manipulation of environmental factors may contribute to preventing the development of obesity even in those strongly genetically
predisposed to it.
Footnotes
Published ahead of print at http://diabetes.diabetesjournals.org on 16 June 2008.
Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work
is not altered. See http://creativecommons.org/licenses/by-nc-nd/3.0/ for details.
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore
be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Accepted June 5, 2008.
Received February 3, 2008.
DIABETES
Sim1 haploinsufficiency in mice induces hyperphagic obesity and developmental abnormalities of the brain. In humans, abnormalities in chromosome 6q16, a region that includes SIM1, were reported in ...obese children with a Prader-Willi-like syndrome; however, SIM1 involvement in obesity has never been conclusively demonstrated. Here, SIM1 was sequenced in 44 children with Prader-Willi-like syndrome features, 198 children with severe early-onset obesity, 568 morbidly obese adults, and 383 controls. We identified 4 rare variants (p.I128T, p.Q152E, p.R581G, and p.T714A) in 4 children with Prader-Willi-like syndrome features (including severe obesity) and 4 other rare variants (p.T46R, p.E62K, p.H323Y, and p.D740H) in 7 morbidly obese adults. By assessing the carriers' relatives, we found a significant contribution of SIM1 rare variants to intra-family risk for obesity. We then assessed functional effects of the 8 substitutions on SIM1 transcriptional activities in stable cell lines using luciferase gene reporter assays. Three mutations showed strong loss-of-function effects (p.T46R, p.H323Y, and p.T714A) and were associated with high intra-family risk for obesity, while the variants with mild or no effects on SIM1 activity were not associated with obesity within families. Our genetic and functional studies demonstrate a firm link between SIM1 loss of function and severe obesity associated with, or independent of, Prader-Willi-like features.
Prevention of obesity should start as early as possible after birth. We aimed to build clinically useful equations estimating the risk of later obesity in newborns, as a first step towards focused ...early prevention against the global obesity epidemic.
We analyzed the lifetime Northern Finland Birth Cohort 1986 (NFBC1986) (N = 4,032) to draw predictive equations for childhood and adolescent obesity from traditional risk factors (parental BMI, birth weight, maternal gestational weight gain, behaviour and social indicators), and a genetic score built from 39 BMI/obesity-associated polymorphisms. We performed validation analyses in a retrospective cohort of 1,503 Italian children and in a prospective cohort of 1,032 U.S. children.
In the NFBC1986, the cumulative accuracy of traditional risk factors predicting childhood obesity, adolescent obesity, and childhood obesity persistent into adolescence was good: AUROC = 0·780·74-0.82, 0·750·71-0·79 and 0·850·80-0·90 respectively (all p<0·001). Adding the genetic score produced discrimination improvements ≤1%. The NFBC1986 equation for childhood obesity remained acceptably accurate when applied to the Italian and the U.S. cohort (AUROC = 0·700·63-0·77 and 0·730·67-0·80 respectively) and the two additional equations for childhood obesity newly drawn from the Italian and the U.S. datasets showed good accuracy in respective cohorts (AUROC = 0·740·69-0·79 and 0·790·73-0·84) (all p<0·001). The three equations for childhood obesity were converted into simple Excel risk calculators for potential clinical use.
This study provides the first example of handy tools for predicting childhood obesity in newborns by means of easily recorded information, while it shows that currently known genetic variants have very little usefulness for such prediction.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
An optimized set of 24 mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) loci, including a discriminatory subset of 15 loci, has recently been defined for the ...typing of Mycobacterium tuberculosis. Here, we evaluated the performances of this MIRU-VNTR typing system in combination with spoligotyping for the detection of transmission chains in a population-based study comprising 91% of culture-confirmed tuberculosis patients reported in 2003 in Hamburg, Germany. Of the 154 isolates investigated, more than 90% had high IS6110 copy numbers (>=6). IS6110 restriction fragment length polymorphism (RFLP) typing resulted in 13 clusters, 5 of which had a confirmed epidemiological link. All five, as well as six of the eight IS6110 clusters with no identified epidemiological link, were perfectly matched by MIRU-VNTR typing with the 24 loci. Two IS6110 clusters were split by differences into 6 to 12 MIRU-VNTR loci, clearly supporting the absence of a link, as judged by contact tracing data. In contrast, only one MIRU-VNTR cluster, grouping what were probably epidemiologically unlinked isolates, was split by IS6110 RFLP. However, these isolates were also distinguished by spoligotyping. Both the optimized 24-locus and 15-locus sets thus showed a comparable to slightly better predictive value, especially when combined with spoligotyping, than the current gold standard IS6110 RFLP for the study of tuberculosis transmission in Hamburg. Because the epidemiological characteristics of this setting are similar to those of many developed countries, these results support the wide applicability of this real-time genotyping approach for population-based studies of M. tuberculosis transmission.
A Genome-Wide Scan for Childhood Obesity–Associated Traits in French Families Shows Significant Linkage on Chromosome 6q22.31-q23.2
David Meyre 1 ,
Cécile Lecoeur 2 ,
Jérôme Delplanque 1 ,
Stephan ...Francke 1 ,
Vincent Vatin 1 ,
Emmanuelle Durand 1 ,
Jacques Weill 1 3 ,
Christian Dina 1 and
Philippe Froguel 1 2
1 Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 8090, Institute of Biology of Lille, Pasteur
Institute, Lille, France
2 Hammersmith Genome Centre and Genomic Medicine, Imperial College, London, U.K
3 Department of Pediatrics, Jeanne de Flandres Hospital, Lille, France
Address correspondence and reprint requests to Philippe Froguel, CNRS UMR 8090, Institute of Biology, Institute Pasteur of
Lille, 1, rue du Pr. Calmette, B.P.447 59021 Lille Cedex, France. E-mail: froguel{at}mail-good.pasteur-lille.fr
Abstract
We conducted a genome-wide search for childhood obesity–associated traits, including BMI ≥95th percentile (PCT95), 97th percentile
(PCT97), and 99th percentile (PCT99) as well as age of adiposity rebound (AAR), which corresponds to the beginning of the
second rise in childhood adiposity. A set of 431 microsatellite markers was genotyped in 506 subjects from 115 multiplex French
Caucasian families, with at least one child with a BMI ≥95th percentile. Among these 115 pedigrees, 97 had at least two sibs
with a BMI ≥95th percentile. Fine-mapping was performed in the seven most positive loci. Nonparametric multipoint analyses
revealed six regions of significant or suggestive linkage on chromosomes 2q33.2-q36.3, 6q22.31-q23.2, and 17p13 for PCT95,
PCT97, or PCT99 and 15q12-q15.1, 16q22.1-q24.1, and 19p13.3-p13.11 for AAR. The strongest evidence of linkage was detected
on chromosome 6q22.31 for PCT97 (maximum likelihood score: 4.06) at the marker D6S287. This logarithm of odds score meets
genome-wide significance tested through simulation (empirical genome-wide P = 0.01 0.0027–0.0254). Six independent ge-nome scans in adults have reported quantitative trait loci on 6q linked to energy
or glucose homeostasis-associated phenotypes. Possible candidate genes in this region include SIM1 , MCHR2 , and PC-1 .
AAR, age of adiposity rebound
LOD, logarithm of odds
MLB, maximum likelihood binomial
MLS, maximum likelihood score
Footnotes
Accepted November 20, 2003.
Received September 5, 2003.
DIABETES
Genetic Analysis of ADIPOR1 and ADIPOR2 Candidate Polymorphisms for Type 2 Diabetes in the Caucasian Population
Martine Vaxillaire 1 ,
Aurélie Dechaume 1 ,
Valérie Vasseur-Delannoy 1 ,
Saida Lahmidi ...1 ,
Vincent Vatin 1 ,
Frédéric Leprêtre 1 ,
Philippe Boutin 1 ,
Serge Hercberg 2 ,
Guillaume Charpentier 3 ,
Christian Dina 1 and
Philippe Froguel 1 4
1 Centre National de la Recherche Scientifique (CNRS) UMR 8090, Institute of Biology and Pasteur Institute, Lille, France
2 Scientific and Technical Institute of Nutrition and Food (ISTNA-CNAM), Institut National de la Santé et de la Recherche Médicale
(INSERM) U557, INRA U1125, Paris, France
3 Department of Endocrinology and Diabetology, Centre Hospitalier Sud Francilien, Corbeil-Essonnes, France
4 Section of Genomic Medicine, Imperial College Genome Centre, Hammersmith Campus, Imperial College London, London, U.K
Address correspondence and reprint requests to Dr. Martine Vaxillaire, CNRS 8090, Institut de Biologie, Institut Pasteur de
Lille, 1 rue du Professeur Calmette, BP 245, 59019 Lille, France. E-mail: martine.vaxillaire{at}pasteur-lille.fr
Abstract
Adiponectin is a metabolic link between adipose tissue and insulin action, mediating part of obesity-associated insulin resistance
and type 2 diabetes. Two adiponectin receptors have been identified, and we investigated whether sequence variations in adiponectin
receptor 1 ( ADIPOR1 ) and adiponectin receptor 2 ( ADIPOR2 ) genes could contribute to the genetic risk for type 2 diabetes in a case-control study of 1,498 Caucasian subjects. We sequenced
the putative functional regions of the two genes in 48 subjects and selected single nucleotide polymorphisms (SNPs) from the
public database. Five SNPs in ADIPOR1 and 12 in ADIPOR2 were tested for association with type 2 diabetes. No SNP of ADIPOR1 showed association in any of the samples from the French population. In contrast, three SNPs of ADIPOR2 showed nominal evidence for association with type 2 diabetes before correction for multiple testing (odds ratio OR 1.29–1.37,
P = 0.034–0.014); only rs767870, located in intron 6, was replicated in an additional diabetes dataset ( n = 636, OR 1.29, P = 0.020) with significant allelic association from the overall meta-analysis of 2,876 subjects (adjusted OR 1.25 95% CI
1.07–1.45, P = 0.0051). In conclusion, our data suggest a modest contribution of ADIPOR2 variants in diabetes risk in the French population.
AdipoR1, adiponectin receptor 1
AdipoR2, adiponectin receptor 2
HWE, Hardy-Weinberg equilibrium
LD, linkage disequilibrium
MAF, minor allele frequency
SNP, single nucleotide polymorphism
UTR, untranslated region
Footnotes
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore
be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
F.L. is currently affiliated with INSERM EA2683, Centre Hospitalier Universitaire de Lille, Lille, France.
Additional information for this article can be found in an online appendix at http://diabetes.diabetesjournals.org .
Accepted December 13, 2005.
Received May 25, 2005.
DIABETES
Ectonucleotide Pyrophosphatase Phosphodiesterase 1 (ENPP1) downregulates insulin signaling by inhibiting the insulin receptor's tyrosine‐kinase. K121Q and other ENPP1 single‐nucleotide polymorphisms ...(SNPs), IVS20delT‐11 and A/G+1044TGA, have been previously associated with obesity in French children, and the risk haplotype QdelTG has also been associated with this condition in both French and German children. Our aim was to perform a case‐control replication study in order to assess the possible association of childhood obesity and overweight with the above‐mentioned ENPP1 SNPs, and with the QdelTG haplotype, in the Italian population. A total of 865 healthy Italian children were studied: 453 normal‐weight, 243 overweight and 169 obese subjects. Genotyping was performed by Taq‐Man or Light‐Cycler Technology. The Q variant of K121Q showed a negative association with overweight‐obesity under both additive (odds ratio (OR) = 0.74, 95% confidence interval (CI) = 0.57–0.97, P = 0.030) and recessive (OR = 0.32, 95% CI = 0.10–0.97, P = 0.035) modes of inheritance. The Z‐score of BMI showed a significant decreasing trend from children K/K homozygous to K/Q heterozygous, and to Q/Q homozygous (0.45 vs. 0.28 vs. −0.19; P = 0.009), according to the additive model. The two other SNPs and the QdelTG haplotype did not exhibit any association with overweight/obesity. This is the first child‐based study showing a protective role of the 121Q variant of ENPP1 against overweight/obesity.
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