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Biomedical subjects

A Hinney

Publications and source records attributed to A Hinney.

At least 55 records · Page 3Linked to original sources
PubMed1999

Missense variants in the human peroxisome proliferator-activated receptor-gamma2 gene in lean and obese subjects.

The peroxisome proliferator-activated receptor-gamma2 (PPARgamma2) is almost uniquely expressed in adipose tissue and is of major importance for fat cell differentiation and lipid metabolism. This study was undertaken to assess whether two missense variants in the PPARgamma2 gene are associated with early-onset obesity. A previously described polymorphism encoding for an amino acid exchange in codon 12 (Pro12Ala) was detected with allele frequencies of 0.13 in 296 markedly obese children and adolescents and 0.14 in 130 lean individuals. A Pro115Gln variant, which had been linked to obesity in Germans in a previous association study, was not detected in any of our obese or lean subjects, who are also of German origin. We conclude from our data that these two variants in the PPARgamma2 gene are unlikely to contribute to the high prevalence of early-onset obesity.

Adolescent↗
PubMed1998

Transmission disequilibrium and sequence variants at the leptin receptor gene in extremely obese German children and adolescents.

Genetic determinants of the degree of obesity and body fat distribution have been demonstrated by family studies. The heritability has been estimated to be in the range 0.2-0.7. Mutation leading to obesity in humans has been described for only two genes, one of them the leptin gene. The leptin gene codes for a cytokine secreted by fat cells that binds to the leptin receptor (Lep-R), which exerts some of its biological functions by expression in the brain. Hence, the Lep-R gene appears to be a promising candidate for the determination of obesity in humans. We isolated genomic DNA clones from the Lep-R gene region and identified a new polymorphic microsatellite marker (OBR-CA) within 80 kb of the translation start of Lep-R. We genotyped this and a second, intragenic microsatellite marker (D1S2852) in 130 nuclear families consisting of extremely obese children and adolescents and both parents. Using the most frequent parental allele of both markers, our analysis revealed a significant transmission disequilibrium for the 266-bp allele of D1S2852 (corrected P-value=0.042). No significant result was obtained with the most frequent allele of OBR-CA (corrected P-value=1.0). However, two rare alleles showed transmission disequilibrium and were subsequently used for constructing a haplotype with the 266-bp allele. This haplotype had a transmission rate of 80% (nominal P-value=0.02). In order to identify the underlying mutation, we sequenced all coding exons of Lep-R and the partially overlapping gene encoding the obese receptor gene-related protein (ob-rgrp) in individuals carrying this haplotype. We found one new mutation (Ser675Thr) in the Lep-R gene in one proband and several other mutations known to be not associated with obesity in other study groups. As this new mutation cannot explain our positive linkage result, the transmission disequilibrium of the 266-bp allele and the high transmission rate of the identified haplotype point towards a mutation in close proximity to marker D1S2852.

Adolescent↗
PubMed1998

Screening for mutations in the neuropeptide Y Y5 receptor gene in cohorts belonging to different weight extremes.

OBJECTIVE: The neuropeptide Y (NPY) Y5 receptor is presumed to be involved in the regulation of food intake. DESIGN: To investigate the possible role of this receptor in weight regulation, the whole coding region of the NPY Y5 receptor gene was screened for mutations using temperature gradient gel electrophoresis (TGGE). Detected mutations were screened in extended cohorts. STUDY COHORTS AND METHODS: Cohorts of 87 extremely obese children and adolescents, 15 underweight subjects and 25 patients with anorexia nervosa (AN) were initially screened by TGGE. Extended samples of these cohorts (160 obese children and adolescents; mean body mass index (BMI) 33.5 +/- 6.4 kg/m2, 128 underweight subjects; mean BMI 18.4 +/- 1.0 kg/m2 and 58 patients with AN; mean BMI 14.6 +/- 1.7 kg/m2) were screened to determine the frequencies of a detected mutation and a detected polymorphism in the NPY Y5 receptor gene. In addition, a previously described polymorphism in the first intron of the NPY Y1 receptor gene was analysed. RESULTS: The coding region of the NPY Y5 receptor gene encompasses one exon. A single mutation, which results in a non-conservative amino acid substitution in the first extracellular domain of the receptor (Glu-4-Ala), and one silent polymorphism (Gly-426-Gly-Gly) at nucleotide position 1278 (G-->A) were detected by TGGE. Both tests for association and linkage to the NPY Y1 and NPY Y5 receptor polymorphisms were negative among all cohorts. The Glu-4-Ala mutation was found only in a single patient with AN and her mother. CONCLUSION: The results do not support a major role of the NPY Y5 receptor gene in the variability of body weight in children and adolescents.

Adolescent↗
PubMed1998

Analysis of the uncoupling protein-1 (UCP1) gene in obese and lean subjects: identification of four amino acid variants.

Uncoupling protein-1 (UCP1) is uniquely expressed in brown adipose tissue (BAT) and of major importance for the tissues thermogenic capacity. This study was undertaken to detect variants in the UCP1 gene by single strand conformational polymorphism (SSCP) analysis and subsequent sequencing, and determine their potential association with obesity. Four variants predicting for amino acid substitutions were detected, of which Arg40Trp (exon 1) and Lys257Arg (exon 5) were rare mutations. In contrast, the allele frequency of a polymorphism in exon 2 predicting for an Ala64Thr substitution was 8.2% in a cohort of 293 obese children and adolescents compared to 4.1% in 134 lean individuals, while the allele frequency of a Met229Leu variant (exon 5) was not markedly different between the obese (10.4%) and lean (12.0%) study groups. Although one of the identified polymorphisms tends to have a higher frequency in obese than in lean subjects, variants of the UCP1 gene do not seem to contribute significantly to the development of early-onset obesity in the German population.

Adolescent↗
PubMed1998

No evidence for involvement of the leptin gene in anorexia nervosa, bulimia nervosa, underweight or early onset extreme obesity: identification of two novel mutations in the coding sequence and a novel polymorphism in the leptin gene linked upstream region.

Mutations in the leptin gene can result in profound obesity in both rodents and humans. In humans, serum leptin levels correlate with body mass index (BMI: kg m(-2)). However, in patients with anorexia nervosa (AN) leptin levels are lower than in BMI-matched healthy controls. We had previously argued that genes involved in weight regulation should be considered as candidate genes for AN. To investigate this hypothesis we screened the coding region of the leptin gene and part of the leptin gene linked upstream region (LEGLUR) in 49 patients with AN and 315 children and adolescents with extreme obesity. Two novel mutations in the coding region (Ser-91-Ser; Glu-126-Gln), each found in a single proband, and a novel polymorphism in the LEGLUR (position -1387 G/A; frequency of both alleles approximately 0.50) were identified. Tests for association of LEGLUR polymorphism alleles were negative by comparing allele frequencies between 115 AN patients, 71 bulimia nervosa patients, 315 extremely obese children and adolescents, 141 healthy underweights and 50 controls that were not selected for body weight. Tests for transmission disequilibrium were also negative. Hence, an influence of variations in the leptin gene on eating disorders or extreme early onset obesity could not be detected.

Adolescent↗
PubMed1998

Screening for variability in the ciliary neurotrophic factor (CNTF) gene: no evidence for association with human obesity.

Systemic administration of the neurocytokine ciliary neurotrophic factor (CNTF) normalizes the obese phenotype of ob/ob and db/db mice. CNTF exerts its multiple effects through a receptor complex whose sequence, localization in hypothalamic nuclei and mode of signal transduction share remarkable similarities with the leptin receptor. In the human CNTF gene, a mutation in the first intron creates a new splice acceptor site, with the resulting mRNA coding for an aberrant protein (Takahashi et al., 1994). Given the potential of CNTF to influence energy homeostasis, this study was undertaken to determine whether variability in the CNTF gene is associated with human obesity. The previously described mutation was found in 30.3% of obese children and adolescents, 7 of which were homozygous (allele frequency 0.163). 29.5% of lean subjects carried the mutation, none of which were homozygous (allele frequency 0.148; corrected p = 1 compared to obese). No further mutations were detected by single strand conformational polymorphism (SSCP) analysis. In conclusion, variants in the CNTF gene are unlikely to be associated with the development of early-onset obesity.

Adolescent↗
PubMed1998

Systematic mutation screening of the pro-opiomelanocortin gene: identification of several genetic variants including three different insertions, one nonsense and two missense point mutations in probands of different weight extremes.

Pro-opiomelanocortin (POMC) is the precursor of melanocortins (adrenocorticotropin: ACTH, beta-endorphin, beta-lipotropin: beta-LPH, corticotropin like intermediate peptide, alpha-, beta- and gamma-melanocyte-stimulating hormone: alpha-, beta- and gamma-MSH) some of which act in the brain to reduce food intake and are potential mediators of leptin action. Recently, three different mutations in the POMC gene (POMC) were identified in two unrelated children that lead to early-onset extreme obesity, adrenal insufficiency, and red hair pigmentation. In the present study we systematically screened the coding region of POMC in 96 extremely obese children and adolescents, 60 healthy underweight individuals and 46 patients with anorexia nervosa (AN) and identified several variants. a) A 9 and an 18 base pair insertion (9bp and 18bp: AGC AGC GGC and AGC AGC GGC AGC AGC GGC, respectively, between codon 73 and 74; 1,2). These in-frame variants lead to the insertion of three or six amino acids (Ser-Ser-Gly; Ser-Ser-Gly-Ser-Ser-Gly) carboxy-terminal to gamma-MSH. Frequencies of the 9bp insertion allele varied between 3 and 5% among the different study groups (Pearson's chi2 P>0.5). b) Both an out-of-frame 6 bp insertion (within codon 176: GGG CCC) leading to the insertion of two amino acids (Arg-Ala) and a premature stop-codon (G-7316-T: Glu-180-Stop) within the gamma-LPH sequence were maternally inherited in an obese female proband. This proband inherited another missense mutation from her father (Glu-188-Gly). c) A missense mutation (G-7016-A; Asp-80-Asn) was observed in a single patient with AN who also harboured the 9bp insertion on a paternally derived haplotype. d) The allelic co-occurence of two silent mutations (C-6982-T and C-7285-T) was detected in two obese subjects. e) Two further silent mutations (C-3832-T; C-7111-G) were detected in an underweight and an obese subject, respectively. We conclude that the POMC gene harbors several different polymorphisms and mutations, none of which can readily be associated with the phenotypes under study.

Adolescent↗
PubMed1998

Systematic mutation screening of the estrogen receptor beta gene in probands of different weight extremes: identification of several genetic variants.

Estrogens are known to have an inhibitory effect on food intake in rodents and primates. Decreased estrogen levels that are found for instance in menopausal woman and in ovarectomized rodents result in body weight gain. Estrogen can act both in the periphery and in the central nervous system via at least two different estrogen receptors (alpha and beta). We systematically screened the coding region and part of the 5' and 3'regions of the estrogen receptor beta gene (ER beta) in 96 extremely obese children and adolescents, 50 patients with anorexia nervosa (AN), 28 patients with bulimia nervosa (BN), and 25 healthy underweight individuals. We detected five different sequence variants in the ER beta: a) A 21 bp deletion (codons 238 to 244) was detected in two obese probands and an underweight individual. b) An 846G-->A transition leading to a nonconservative amino acid substitution (G-250-S) was found in two obese male probands. Both a) and b) were located within the flexible hinge region between DNA and ligand binding domain. c) For a 1082G-->A polymorphism we found suggestive evidence for an association between the more common 1082G-allele and anorexia nervosa (nominal p=0.04). d) One silent mutation (1421T-->C) was found solely in two obese probands. e) A common variant is located in the 3' nontranslated region at position 1730(A-->G). We did not detect association of this polymorphism to any of the analyzed phenotypes. We conclude that the ER beta harbors several different mutations and polymorphisms, none of which can readily be associated with the phenotypes under study.

Adolescent↗
PubMed1997

The 5-HT transporter gene-linked polymorphic region (5-HTTLPR) in evolutionary perspective: alternative biallelic variation in rhesus monkeys. Rapid communication.

By conferring allele-specific transcriptional activity on the 5-HT transporter gene promoter in humans, the 5-HT transporter gene-linked polymorphic region (5-HTTLPR) influences a constellation of personality traits related to anxiety and increases the risk for neurodevelopmental, neurodegenerative, and psychiatric disorders. Here we have analyzed the presence and variability of the 5-HTTLPR in several species of primates including humans, and other mammals. PCR, Southern blot, and sequence analyses of the 5-HT transporter gene's 5'-flanking region in different mammalian species confirmed the presence of the 5-HTTLPR in platyrrhini and catarrhini (hominoids, cercopithecoids) but not in prosimian primates and other mammals. Since the 5-HTTLPR is unique to humans and simian primates, a progenitor 5-HTTLPR sequence may have been introduced into the genome some 40 Mio, years ago. In humans the majority of alleles are composed of either 14 or 16 repeat elements, while alleles with 18 or 20 repeat elements are rare. In contrast, great apes including orang-utan, gorilla, and chimpanzee display a high prevalence of alleles with 18 and 20 repeat elements. In hominoids all alleles originate from variation at a single locus (polymorphic locus 1). In the 5-HTTLPR of rhesus monkeys (rh5-HTTLPR) we found an alternative locus for length variation (polymorphic locus 2) generated by a 21 bp insertion/deletion event. The existence of a distinct biallelic variation of the 5-HTTLPR in rhesus monkeys but similar allele and genotype frequencies in this species and humans supports the notion that there may be a relationship between functional 5-HT transporter expression, anxiety-related traits, and the complexity of socialization in human and non-human primate populations.

Alleles↗
PubMed1997

Evaluation of a Cys23Ser mutation within the human 5-HT2C receptor gene: no evidence for an association of the mutant allele with obesity or underweight in children, adolescents and young adults.

Serotonin is a neurotransmitter involved in a large number of psychophysiological processes including the regulation of mood, arousal, aggression, sleep, learning, nociceptions, nerve growth and importantly, appetitive functions. Alterations of 5-HT receptor activity have been shown to occur in many psychiatric diseases including depression, anxiety, eating disorders, schizophrenia etc. Hence, genetic variation in genes coding for serotonin receptor proteins might well be involved in the genetic predisposition to these diseases and therefore are of great pharmacogenetic relevance. Knockout mice deficient of a functional 5-HT2C receptor have implicated a potential role of this receptor subtype in the serotonergic control of appetite. A Cys23Ser mutation in the human 5-HT2C receptor gene discovered recently prompted us to investigate this mutation with regard to the development of human obesity. We have evaluated this mutation in 241 obese children and adolescents (mean BMI > or = 97th percentile), 80 normal weight children (BMI 5th-85th percentile) and 92 underweight probands (BMI < or = 15th percentile) for a possible association with obesity. The frequencies of the mutant allele in all three weight groups (obese subjects: 0.1597; normal weight: 0.168; underweight: 0.1575) were very similar. Association as well as linkage studies were negative. Therefore it is unlikely that this receptor mutation plays a direct role in the development of human obesity.

Adolescent↗
PubMed1997

Serotonin transporter gene-linked polymorphic region: allele distributions in relationship to body weight and in anorexia nervosa.

Several lines of evidence implicate a role for the serotonergic system in body weight regulation and eating disorders. The magnitude and duration of postsynaptic responses to serotonin (5-HT) is directed by the transport into and release from the presynaptic neuron. Recently, a common polymorphism of a repetitive element in the region of the serotonin transporter (5-HTT) gene-linked polymorphic region (5-HTTLPR) was identified that results in a system of two common alleles. The activity of the 5-HTT, as measured in in vitro assays and in human lymphoblastoid cell lines, is dependent on the respective genotype. We thus hypothesized that this polymorphism is relevant for weight regulation in general and is possibly involved in the etiology of anorexia nervosa (AN). Allele frequencies and genotypes were determined in a total of 385 unrelated obese children, adolescents and adults, 112 underweight subjects and 96 patients with AN. Furthermore, both parents of 98 obese children and adolescents and of 55 patients with AN, respectively, were genotyped, thus allowing to test for both association and linkage. The comparison of allele frequencies between obese and underweight probands provided no evidence for a major role of the 5-HTTLPR in weight regulation. Patients with AN had allele frequencies not significantly different to those observed for obese and underweight individuals.

Adolescent↗
PubMed1997

Beta 3-adrenergic-receptor allele distributions in children, adolescents and young adults with obesity, underweight or anorexia nervosa.

OBJECTIVE: The missense mutation (64Trp to 64Arg) in the beta 3-adrenergic-receptor has previously been described to confer a genetic predisposition to the development of obesity. DESIGN: To test the hypothesis we evaluated allele frequencies in children, adolescents and young adults who belonged to different weight groups that were delineated with percentiles for the body mass index (BMI; kg/m2). SUBJECTS: 99 underweight probands (BMI < or = 15th percentile). 80 normal weight probands (BMI: 5th-85th percentile). 238 obese children and adolescents (BMI > or = 97th percentile). 84 patients with anorexia nervosa (AN). MEASUREMENTS: The cohorts were screened by polymerase chain reaction with subsequent restriction fragment length polymorphism (PCR-RFLP) analysis. Data were statistically analysed for association. In addition to these case control studies, the transmission disequilibrium test (TDT) was applied to 80 families of obese probands and to 52 families of patients with AN. RESULTS: Both the tests for association and linkage were negative. The Trp64Arg allele frequencies in the three weight groups (obesity: 0.071; normal weight: 0.081; underweight: 0.056) and the AN patients (0.054) were similar. Extremely obese individuals showed no excess of the Trp64Arg allele. No homozygotes for the Trp64Arg allele were detected. CONCLUSION: Heterozygosity for the Trp64Arg allele is not of major importance in regulation of body weight in individuals younger than 35 y. Additionally, the extreme obese subgroup is not enriched for the polymorphism.

Adolescent↗
PubMed1997

Further support for linkage of extreme obesity to the obese gene in a study group of obese children and adolescents.

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.

Adolescent↗
PubMed1995

Detection of two hypervariable (ATTTT)n loci in the human genome.

Object of this investigation was the isolation of a single-locus probe from a multi-locus fingerprint. Individual specific multi-locus fingerprints in man were generated by using the oligonucleotide probe (ATTTT)5. An isolated (ATTTT)5-positive DNA fragment was analyzed using polymerase chain reaction (PCR) cycle-sequencing and nonradioactive direct-blotting electrophoresis. A digoxigenated oligonucleotide synthesized according to this sequence was used as a single-locus probe. Two hypervariable loci were detected on Southern blots. Formal genetic investigations for the two loci were performed in order to estimate the allele frequencies. Locus 1 shows an individual-specific banding pattern with an autosomal-codominant inheritance and can be used for forensic investigations. Locus 2 also represents a polymorphic pattern, but the inheritance is not according to the Mendelian rules. Probably we have detected a highly mutagenic locus in the human genome.

Base Sequence↗
PubMed1994

TGGE and HIEF: a comparison of two methods in the detection of carriers of the Z mutation in the alpha-1-antitrypsin gene.

Alpha-1-antitrypsin (alpha-1-AT) deficiency can lead to juvenile liver cirrhosis and lung emphysema in adulthood. The deficiency Z allele is caused by a base transition. Temperature gradient gel electrophoresis (TGGE) and hybrid isoelectric focusing (HIEF) were used to detect carriers of the Z mutation of the alpha-1-AT gene. The resulting data were compared. To verify carriers at the sequence level, a manual nonradioactive sequencing strategy was established. Among our sample of carriers of the Z mutation, two were not detected by HIEF that could be identified by TGGE. DNA of all TGGE identified individuals harboring the Z mutation of the alpha-1-AT gene were sequenced nonradioactively. All carriers harbored a G to A transition at position 11.940. This mutation is described to cause the altered protein.

Alleles↗
PubMed1994

Selection of unrelated bone marrow donors by PCR-SSP typing and subsequent nonradioactive sequence-based typing for HLA DRB1/3/4/5, DQB1, and DPB1 alleles.

HLA incompatibility between bone marrow recipients and unrelated donors is one of the main obstacles in bone marrow transplantation. HLA class I and generic class II DR and DQ typing is generally performed by serology. Precise subtyping of HLA class II genes, however, can only be achieved by molecular genetic methods. Here, the final selection of serologically pretyped unrelated bone marrow donors by confirmatory PCR-SSP (PCR-sequence-specific primers) typing and subsequent nucleic acid sequence analysis of the second exon of DRB1, DRB3, DRB4, DRB5, DQB1, and DPB1 alleles is presented. Serologically identical potential marrow donors and their corresponding recipients were analyzed for HLA-DRB identity by PCR-SSP analysis. After solid-phase single-strand separation, direct sequencing of the allele- or group-specific DRB amplified products was performed by applying fluorophorlabelled sequencing primers. Electrophoretically separated sequencing products were detected by means of an automated DNA sequencer. Group-specific amplification and sequencing of DQB1 alleles was carried out for all potential bone marrow donors and recipients, while only the final donor-recipient pair was analyzed for DPB1 alleles. Thus, the presented amplification strategy in combination with direct sequencing of PCR products allows matching of bone marrow transplant pairs with the highest degree of reliability for the assessment of HLA class II identity.

Base Sequence↗