ZusammenfassungDie Varianz des Körpergewichtes wird durch erbliche Faktoren mitbestimmt. Molekulargenetische Studien konnten jedoch bisher nur einen kleinen Teil der Variabilität des BMI erklären. Monogene Formen der Adipositas sind sehr selten. Dabei kann der Wegfall eines einzigen Genprodukts zu extremer Adipositas führen. Ein komplexes Zusammenspiel vieler Genvarianten trägt zum BMI bei (polygene Adipositas). Dabei ist der Beitrag jeder einzelnen Variante zum Körpergewicht eher gering. In einer groß angelegten Meta-Analyse konnten kürzlich 97 polygene Varianten identifiziert werden, die mit Adipositas assoziiert sind. Neben den genomischen Varianten spielen auch epigenetische Mechanismen bei der Gewichtsregulation eine Rolle. Die epigenetische Ausstattung eines Menschen kann sich im Laufe des Lebens verändern. Sie kann als Schnittstelle zwischen genetischen und umweltbedingten Einflüssen angesehen werden. Es ist vorstellbar, dass in der Zukunft genetische und epigenetische Marker eingesetzt werden können, um eine Prädisposition zur Adipositas zu erkennen und ggf. auch die Therapie zu verbessern.

Noradrenergic neurotransmission influences executive functions, attentional performance, and general alertness, involving neuronal networks affected in attention deficit/hyperactivity disorder (ADHD). The norepinephrine transporter facilitates the reuptake of norepinephrine and dopamine in the prefrontal cortex and represents the main target of atomoxetine, an effective drug in the treatment of ADHD. Due to its influence on catecholaminergic signaling, variants of the coding gene (SLC6A2) have been widely investigated in ADHD. Several previous studies report an association between single nucleotide polymorphisms located in SLC6A2 and ADHD; however, the findings are inconsistent. The variant A-3081T (rs28386840) has been shown to have major influence on the expression levels of SLC6A2 due to sequence alteration at a repressor binding site, with the T-allele being associated with ADHD. We tested this potential association of A-3081T in a German family-based ADHD sample of 235 children from 162 families, which has a power >99% based on the previously reported odds ratios. There was no evidence for an overtransmission of the risk allele T (transmission rate: 48.5%, P = 0.55). We conclude that A-3081T is not a major risk variant in our ADHD sample, though SLC6A2 remains an interesting candidate gene in ADHD, especially for the inattentive subtype.

Attention-deficit/hyperactivity disorder (ADHD) is a common, highly heritable neurodevelopmental syndrome characterized by hyperactivity, inattention and increased impulsivity. To detect micro-deletions and micro-duplications that may have a role in the pathogenesis of ADHD, we carried out a genome-wide screen for copy number variations (CNVs) in a cohort of 99 children and adolescents with severe ADHD. Using high-resolution array comparative genomic hybridization (aCGH), a total of 17 potentially syndrome-associated CNVs were identified. The aberrations comprise 4 deletions and 13 duplications with approximate sizes ranging from 110 kb to 3 Mb. Two CNVs occurred de novo and nine were inherited from a parent with ADHD, whereas five are transmitted by an unaffected parent. Candidates include genes expressing acetylcholine-metabolizing butyrylcholinesterase (BCHE), contained in a de novo chromosome 3q26.1 deletion, and a brain-specific pleckstrin homology domain-containing protein (PLEKHB1), with an established function in primary sensory neurons, in two siblings carrying a 11q13.4 duplication inherited from their affected mother. Other genes potentially influencing ADHD-related psychopathology and involved in aberrations inherited from affected parents are the genes for the mitochondrial NADH dehydrogenase 1 α subcomplex assembly factor 2 (NDUFAF2), the brain-specific phosphodiesterase 4D isoform 6 (PDE4D6) and the neuronal glucose transporter 3 (SLC2A3). The gene encoding neuropeptide Y (NPY) was included in a ∼3 Mb duplication on chromosome 7p15.2-15.3, and investigation of additional family members showed a nominally significant association of this 7p15 duplication with increased NPY plasma concentrations (empirical family-based association test, P=0.023). Lower activation of the left ventral striatum and left posterior insula during anticipation of large rewards or losses elicited by functional magnetic resonance imaging links gene dose-dependent increases in NPY to reward and emotion processing in duplication carriers. These findings implicate CNVs of behaviour-related genes in the pathogenesis of ADHD and are consistent with the notion that both frequent and rare variants influence the development of this common multifactorial syndrome.

The role of the obese gene in human obesity is presently unclear. Evidence for linkage of markers flanking the gene to obesity has been found in some but not all studies. We investigated transmission disequilibrium between two highly polymorphic microsatellite markers (D7S504 and D7S1875) flanking the human obese gene (OB) and extreme obesity in a study group of German children and adolescents. Due to the early onset and severity of obesity in the ob/ob mouse we hypothesized that especially children and adolescents with extreme obesity are enriched for possible mutations in the human OB. The analysis of 88 trios (index probands and both parents) for transmission disequilibrium of a haplotype which has previously been determined to be linked to extreme obesity (Reed et al., 1996) revealed a one-sided transmission disequilibrium test (TDT) p-value of 0.039. Post hoc analyses revealed one-sided TDT p-values of 0.015 for the 214 bp allele of D7S1875 (corrected p-value = 0.03) and 0.215 for the 145 bp allele of D7S504 (corrected p-value = 0.43). These findings substantiate the evidence for linkage of extreme obesity to OB.

Previous genome-wide linkage studies applied the affected sib-pair design; one investigated extended pedigrees of a genetic isolate. Here, results of a genome-wide high-density linkage scan of attention-deficit/hyperactivity disorder (ADHD) using an array-based genotyping of ∼50 K single nucleotide polymorphism (SNPs) markers are presented. We investigated eight extended pedigrees of German origin that were non-related, not part of a genetic isolate and ascertained on the basis of clinical referral. Two parametric analyses maximizing LOD scores (MOD) and a non-parametric analysis for both a broad and a narrow phenotype approach were conducted. Novel linkage loci across all families were detected at 2q35, 5q13.1, 6q22-23 and 14q12, within individual families at 18q11.2-12.3. Further linkage regions at 7q21.11, 9q22 and 16q24.1 in all families, and at 1q25.1, 1q25.3, 9q31.1-33.1, 9q33, 12p13.33, 15q11.2-13.3 and 16p12.3-12.2 in individual families replicate previous findings. High-resolution linkage mapping points to several novel candidate genes characterized by dense expression in the brain and potential impact on disorder-relevant synaptic transmission. Our study provides further evidence for common gene effects throughout different populations despite the complex multifactorial etiology of ADHD.

Altered neurotransmission has been suggested to be a crucial factor in the pathophysiology of attention-deficit/hyperactivity disorder ADHD. Subsequently genes encoding for synaptic proteins have been investigated in candidate gene studies. These proteins mediate the release of neurotransmitters into the synaptic cleft in the process of signal transduction by forming a transient complex, enabling the junction of vesicle and synaptic membrane. One of the core proteins of this complex is the synaptosomal-associated protein 25 (SNAP25). It is one of the most validated candidate genes in ADHD according to meta-analyses. However, differing results were observed in previous studies, some of which were not able to observe association with ADHD. In this study we aimed to investigate association of genetic variants of SNAP25 located in the putative promoter region of SNAP25 and a SNP in intron 8, previously reported to associated with ADHD. A family based design was applied to detect preferential transmission of genetic variants. In our German ADHD sample no preferential transmission of either variant could be observed. Further investigation considering sub-sample analysis regarding response to D-amphetamine could enlight the role of SNAP25 in ADHD.

Effects of a Protein Optimized Diet Combined with Moderate Resistance Training on the Postoperative Course in Older Patients with Hip Fracture

Alterations in the serotonergic pathway have been implicated in the pathogenesis of attention-deficit/hyperactivity disorder (ADHD). The aim of this study was to investigate seven genetic variants in three genes (serotonin transporter (5-HTT), serotonin receptor 1B (5-HTR1B) and serotonin receptor 2A (5-HTR2A)), which have previously been shown to be associated with ADHD. The polymorphisms under investigation were the 5-HTTLPR, the VNTR in intron 2 and the 3'UTR SNP in 5-HTT, the 5-HTR1B variations 861G > C and 102T > C, and the 5-HTR2A variations His452Tyr and 1438G > A. We genotyped these variants in a sample of 102 families with 229 children with ADHD according to DSM-IV criteria. Among the affected children, 69% fulfilled criteria for the combined type, 27% for the predominantly inattentive type, and 4% for the predominantly hyperactive-impulsive type. Associations were tested by the pedigree transmission disequilibrium test (PDT). All investigated polymorphisms in serotonergic candidate genes showed no association to ADHD in our sample. Earlier studies of these polymorphisms had also shown inconsistent results, with some studies reporting significant associations and others demonstrating no association. This discordance between studies may reflect variation in patient ascertainment criteria, genetic heterogeneity, too low statistical power for the expected effects or false positive results in the initial reports. We cannot rule out the possibility that other variations in the investigated genes contribute to the etiology of ADHD.

Attention deficit/hyperactivity disorder (ADHD) is a highly heritable common neurodevelopmental disorder with onset in childhood. A coding SNP (rs6265, Val66Met) of the brain-derived neurotrophic factor gene (BDNF) has recently been associated with ADHD. More specifically, paternal over-transmission of the common Val66 allele to affected children had been observed. We aimed to confirm these findings in a large, sufficiently powered, and well characterized German ADHD family sample. The Val66Met polymorphism of BDNF was genotyped in 294 families comprising one or more affected sibs (468 children). Contrary to previous reports, we did not observe over-transmission of the common Val66 allele, from either parent to affected children. We did not find support for an involvement of the Val66 allele of the Val66Met polymorphism of BDNF in the pathogenesis of ADHD in our sample.

Effects of a Protein Optimized Diet Combined with Moderate Resistance Training on the Postoperative Course in Older Patients with Hip Fracture

CONTEXT:Autosomal dominant inheritance of mutations in the melanocortin-4 receptor gene (MC4R) is currently regarded as the most relevant genetic cause for extreme obesity and affects 2-4% of extremely obese individuals.OBJECTIVE:Our objective was to assess the relevance of MC4R mutations in a German population-based sample.DESIGN AND SETTING:We conducted a mutation screen of the MC4R gene by capillary electrophoresis-based single-strand conformation polymorphism analysis and denaturing HPLC.PARTICIPANTS:Subjects included 4068 individuals of a German population-based study group [Kooperative Gesundheitsforschung im Raum Augsburg, Survey 4 (KORA-S4); i.e. Cooperative Health Research in the Region of Augsburg] and 1003 German obese adults (body mass index >or= 30 kg/m(2)).MAIN OUTCOME MEASURES:Samples with aberrant capillary electrophoresis-based single-strand conformation polymorphism analysis/denaturing HPLC patterns were resequenced. Functional studies including agonistic receptor stimulation (Nle-D-Phe-alpha-, alpha-, and beta-MSH) and cell surface expression assays were performed.RESULTS:Sixteen (six novel) coding nonsynonymous mutations were detected in 27 heterozygous individuals of KORA-S4. Four of the mutation alleles led to impaired receptor function in vitro; however, none of these six heterozygous mutation carriers was obese (body mass index >or= 30 kg/m(2)). In the obese adults, six coding nonsynonymous and a nonsense mutation were detected in 13 individuals. Only the nonsense mutation allele entailed impaired receptor function.CONCLUSIONS:Our study depicts prevalence, spectrum, and functional characterization of MC4R mutations in the German population-based sample KORA-S4. In this epidemiological study group, individuals heterozygous for nonsynonymous MC4R mutation alleles entailing impaired function were not obese. Furthermore, nonsynonymous MC4R mutations causing impaired receptor function were rare in German obese adults (two in 1003 = 0.2%).

CONTEXT:The melanocortin 4 receptor (MC4R) is an essential regulator of energy intake and body weight. Recently, the V103I polymorphism of MC4R has been shown to be negatively associated with body mass index. This suggests that serum lipids and blood pressure in individuals carrying the 103I allele might be influenced as well.OBJECTIVE:The objective of this study was to determine whether the most common polymorphism of the MC4R, V103I, affects serum lipid levels and/or blood pressure.DESIGN, SETTING, AND PARTICIPANTS:The study participants were 1173 consecutive patients undergoing cardiac catheterization; they were genotyped for the rs2229616 G-->A substitution at codon 103 (V103I polymorphism) of the MC4R gene. Patients had strictly fasted for at least 12 h before blood samples were drawn. The average age of the patients was 60.9 yr; 72% were males.MAIN OUTCOME MEASURES:The main outcome measures were body mass index, serum lipids, aortic and systolic blood pressure, and MC4R polymorphism V103I.RESULTS:Heterozygous carriers of the 103I allele had significantly lower triglyceride levels than individuals homozygous for the wild-type allele (127 vs. 168 mg/dl mean total triglyceride; P = 0.001 or 0.009 after Bonferroni adjustment for seven tests). No homozygous carriers of the 103I allele were present in the study population.CONCLUSIONS:Our study suggests an influence of MC4R activity on triglyceride levels in cardiovascular patients.

Effects of a Protein Optimized Diet Combined with Moderate Resistance Training on the Postoperative Course in Older Patients with Hip Fracture

OBJECTIVE The importance of the melanin-concentrating hormone (MCH) system for regulation of energy homeostasis and body weight has been demonstrated in rodents. We analysed the human MCH receptor 1 gene (MCHR1) with respect to human obesity. DESIGN This consisted of genomic screening of 13.4 kb encompassing the MCHR1 in extremely obese German children and adolescents and association analyses for two coding single nucleotide polymorphisms (SNPs). To confirm initial positive association results, additional association studies and transmission disequilibrium tests in further German, Danish, French and American samples were conducted. Selected SNPs were investigated using functional in vitro studies and reporter gene assays. METHODS Single-stranded conformation polymorphism analysis, re-sequencing, PCR-restriction fragment length polymorphism analyses, tetra-primer amplification refractory mutation systems, matrix-assisted laser desorption/ionization time of flight mass spectrometry and reporter gene assays were carried out as well as measuring inositol phosphate formation, inhibition of cAMP formation and activation of p42/44 MAP kinase. RESULTS We identified 11 infrequent variations and two SNPs in the MCHR1 coding sequence and 18 SNPs (eight novel) in the flanking sequence. Association and transmission disequilibrium with obesity were detected for several SNPs in independent study groups of German obese children and adolescents and controls. In two German samples, encompassing 4056 and 295 individuals, trends towards association with obesity were detected. Findings in a second epidemiological German sample and in Danish, French and American samples were negative. Functional in vitro studies as well as reporter gene assays revealed no significant results. CONCLUSION Our initial association of MCHR1 alleles/haplotype detected might be related to juvenile-onset obesity, conditional on a particular genetic and/or environmental background. Alternatively, we could not exclude the possibility that the initially detected association represented a false positive finding.

Background: The prevalence of childhood obesity is steadily increasing. Weight regulation and food intake are subject to complex regulatory mechanisms. The leptinergic-melanocortinergic system is known to be of major importance. Aim of the study: Identification of mutations in the melanocortin 4 receptor gene (MC4R) and of phenotypic effects of detected mutations in German obese children and adolescents. Family specific and cardiovascular risk factors were also analysed. Patients: Consecutive ascertainment of 90 obese children and adolescents with a medium BMI SDS of + 2.6, age range 3 to 16 years. Methods: Mutation screen within the MC4R was carried out by denaturing high performance liquid chromatography (dHPLC) and re-sequencing of samples with aberrant dHPLC patterns. Eating behaviour and obesity-associated diseases within the families were evaluated by semi-structured interviews. Metabolic evaluation included: oral glucose tolerance test (OGTT, WHO criteria) for calculation of insulin resistance (Homeostasis Model Assessment, HOMA) and insulin sensitivity index (ISI), lipid panel for lipid status, blood pressure measurement and abdominal ultrasound. Results: Three patients were heterozygous MC4R mutation carriers (Thr112Met, Ala175Thr and Gly181Asp). Gly181Asp leads to a complete loss of function; whereas Thr112Met and Ala175Thr lead to a reduced receptor function. The patients with heterozygous MC4R mutations had BMIs, cholesterol levels and waist to hip ratios (W/H) that did not differ from the rest of our study group. The overall occurrence of hypertriglyceridemia (34%) and hypercholesterinemia (22%) was correlated with the W/H-ratio. The overall incidence of impaired glucose tolerance was 12%. In those with a normal glucose tolerance 68% already had an increased HOMA (mean 3.12; reference value < 1.9) and decreased ISI (mean 4.3; reference value > 7.2). The patients with MC4R mutations had a normal glucose tolerance with similar HOMA and ISI values compared to the rest of the patients. Hypertension was found in 24% of all cases and blood pressure was correlated with BMI (r+ 0.8). None of the patients with MC4R mutations were hypertensive. Leptin levels did not discriminate between patients with MC4R mutations and the other patients. Five patients harboured one of the MC4R polymorphisms (Val103Ile, Ile251Leu). These were phenotypically indistinguishable from the individuals without MC4R variants. Conclusion: We detected MC4R mutations (Thr112Met, Ala175Thr and GIy181Asp) in 3.3% and MC4R polymorphisms (Val103Ile, Ile251Leu) in 5.5% of the analysed obese children and adolescents, respectively. The patients with MC4R mutations did not show a higher metabolic risk compared to obese children and adolescents without mutations. However the total study group is prone to an increased risk for developing metabolic and cardiovascular diseases.

Three groups have previously performed genome scans in attention-deficit/hyperactivity disorder (ADHD); linkage to chromosome 5p13 was detected in all of the respective studies. In the current study, we performed a whole-genome scan with 102 German families with two or more offspring who currently fulfilled the diagnostic criteria for ADHD. Including subsequent fine mapping on chromosome 5p, a total of 523 markers were genotyped. The highest nonparametric multipoint LOD score of 2.59 (empirical genome-wide significance 0.1) was obtained for chromosome 5p at 17 cM (according to the Marshfield map). Subsequent analyses revealed (a) a higher LOD score of 3.37 at 39 cM for a quantitative severity score based on symptoms of inattention than for hyperactivity/impulsivity (LOD score of 1.11 at 59 cM), and (b) an HLOD of 4.75 (empirical genome-wide significance 0.001) based on a parametric model assuming dominant inheritance. The locus of the solute carrier 6A3 (SLC6A3; dopamine transporter 1; DAT1) localizes to 5p15.33; the gene has repeatedly been implicated in the etiology of ADHD. However, in our sample the DAT1 VNTR did not show association with ADHD. We additionally identified nominal evidence for linkage to chromosomes 6q, 7p, 9q, 11 q, 12q and 17p, which had also been identified in previous scans. Despite differences in ethnicity, ascertainment and phenotyping schemes, linkage results in ADHD appear remarkably consistent.

Attention-deficit/hyperactivity disorder (ADHD) is the most common behavioral disorder in childhood with substantial heritability. Pharmacological and molecular genetic studies as well as characterization of animal models have implicated serotonergic dysfunction in the pathophysiology of ADHD. Here, we investigated the effect of polymorphic variants in the gene of the tryptophan hydroxylase-2 ( TPH2 ), the rate-limiting enzyme of serotonin (5-HT) synthesis in the brain, in children and adolescents with ADHD. We analyzed three single nucleotide polymorphisms (SNPs) in and downstream of the transcriptional control region of the TPH2 gene in 103 families with 225 affected children. Allelic association in families with more than one affected child was assessed using the pedigree disequilibrium test. Preferential transmissions were detected for the two SNPs in TPH2 's regulatory region (rs4570625, P =0.049; rs11178997, P =0.034), but not for the third SNP in intron 2 (rs4565946, P =0.3517). Haplotype analysis revealed a strong trend of association between the regulatory region SNPs (rs4570625, rs11178997) and ADHD ( P =0.064). Our results link potentially functional TPH2 variations to the pathophysiology of ADHD, and further support the relevance of 5-HT in disorders related to altered motor activity and cognitive processes.