Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Deficiency of protein Gs (Gs; OMIM no.103580), the stimulatory regulator of adenylyl cyclase, is associated with resistance to PTH and other hormones, sc calcifications, short stature, and skeletal defects (Albright's hereditary osteodystrophy). It is caused by heterozygous loss of function mutations in GNAS 1, the gene encoding the alpha-subunit of Gs. Obesity is a classical feature of patients with Gs deficiency, but the mechanism leading to fat accumulation has not been elucidated. We measured glycerol flux, using a nonradioactive tracer dilution approach, to analyze the lipolytic response to epinephrine in 6 patients with Gs deficiency and PTH resistance and compared it to six age-matched normal controls and nine massively obese children. Basal glycerol production was reduced by 50%, and lipolytic response to epinephrine was reduced by 67%, in Gs-deficient children, as compared with controls. The degree of impairment of lipolysis was similar in Gs-deficient children who were only moderately overweight and in morbidly obese children. These findings extend the spectrum of hormonal resistance in Gs deficiency. Besides beta-adrenergic receptors, Gs protein itself should be examined as a possible step involved in the decreased lipolysis observed in common obesity.
 ...
PMID:Resistance to the lipolytic action of epinephrine: a new feature of protein Gs deficiency. 1056 60

Genetic analysis of the GNAS gene was performed in a patient with idiopathic renin-dependent hypertension, PTH resistance, and Albright's hereditary osteodystrophy-like characteristics such as a round face, short stature, obesity, and mental retardation (IQ, 49). Mutational analysis showed no mutations in exons 1-13 or in any exon-intron boundary. However, methylation-status analysis revealed a bialleic methylation defect in GNAS exon 1A, indicating that a GNAS-imprinting defect is the cause of her PTH resistance, as commonly observed in pseudohypoparathyroidism type IB. The imprinting defect, however, could not explain her renin-dependent hypertension and Albright's hereditary osteodystrophy-like phenotype. There are many types of X-linked mental retardation. Syndromic X-linked mental retardation, such as X-linked alpha-thalassemia mental retardation syndrome and Rett syndrome, is reportedly associated with abnormal imprinting. To further investigate this unexplained phenotype, we tested whether this patient showed skewed X-inactivation (SXI) presumably as a result of postinactivation selection against cells with a mutated gene on the active X-chromosome. Completely SXI was observed in the DNA from her leukocytes, urinary sediment, and renal tissue. A mutation of the X-chromosome might be correlated with this phenotype because of a close association between completely SXI and X-chromosomal mutation.
 ...
PMID:Completely skewed X-inactivation in a mentally retarded young female with pseudohypoparathyroidism type IB and juvenile renin-dependent hypertension. 1284 41

Albright hereditary osteodystrophy (AHO) is characterized by a symptom complex including short stature, brachymetacarpia, obesity, round facies, cutaneous osteomas, and mental retardation. AHO is caused by mutations in the GNAS-gene localized on chromosome 20 encoding for Gsalpha protein, a signal transducer of endocrine pathways. Therefore, AHO is often associated with endocrinopathy such as pseudohypoparathyroidism or hypothyroidism. A nine-month-old boy presented with typical features of this syndrome. The diagnosis was confirmed by biochemical and molecular analyses. An unusual feature was calcinosis cutis at such an early age, which led to extensive differential diagnostic procedures.
 ...
PMID:[Calcinosis cutis in Albright hereditary osteodystrophy: pseudohypoparathyroidism type Ia]. 1627 Feb 3

Albright hereditary osteodystrophy (AHO) is a genetic disorder caused by heterozygous inactivating mutations in GNAS, the gene that encodes the alpha-chain of Gs (G alpha s). This syndrome is associated with short stature, obesity, brachydactyly, and subcutaneous ossifications. Patients with GNAS mutations on maternally-inherited alleles are resistant to multiple G-protein-coupled hormones, including parathyroid hormone (PTH), thyroid-stimulating hormone (TSH), luteinizing hormone/follicle-stimulating hormone (LH/FSH), and glucagon. This variant of AHO, termed pseudohypoparathyroidism (PHP) type 1a, is due to tissue-specific paternal imprinting of G alpha s. We investigated whether patients with PHP type 1a exhibited evidence of resistance to growth hormone releasing hormone (GHRH) (1), another hormone requiring G alpha s function. In addition, G alpha s transcripts are imprinted in the pituitary somatotrophs responsible for growth hormone (GH) secretion which could thereby influence GHRH-dependent stimulation of somatotrophs. We therefore hypothesized that patients with PHP type 1a may be GH deficient which could contribute to the obesity and short stature in this condition. We found that GH deficiency is common in PHP type 1a (69%) with a prevalence that is much greater than in the general population (0.03%). We propose that GH status be evaluated in all patients with this condition. Treatment with recombinant GH could lead to improvements in height in children, as well as other physical (eg, obesity, hyperlipidemia, osteoporosis, reduced renal function) and psychological (fatigue and diminished sense of well-being) parameters in GH-deficient PHP type 1a patients of all ages.
 ...
PMID:Short stature, obesity, and growth hormone deficiency in pseudohypoparathyroidism type 1a. 1667 31

The heterotrimeric G protein alpha-subunit G(s)alpha is ubiquitously expressed and mediates receptor-stimulated intracellular cAMP generation. Its gene Gnas is a complex imprinted gene which uses alternative promoters and first exons to generate other gene products, including the G(s)alpha isoform XL alpha s and the chromogranin-like protein NESP55, which are specifically expressed from the paternal and maternal alleles, respectively. G(s)alpha itself is imprinted in a tissue-specific manner, being biallelically expressed in most tissues but paternally silenced in a few tissues. Gene targeting of specific Gnas transcripts demonstrates that heterozygous mutation of G(s)alpha on the maternal (but not the paternal) allele leads to early lethality, perinatal subcutaneous edema, severe obesity, and multihormone resistance, while the paternal mutation leads to only mild obesity and insulin resistance. These parent-of-origin differences are the consequence of tissue-specific G(s)alpha imprinting. XL alpha s deficiency leads to a perinatal suckling defect and a lean phenotype with increased insulin sensitivity. The opposite metabolic effects of G(s)alpha and XL alpha s deficiency are associated with decreased and increased sympathetic nervous system activity, respectively. NESP55 deficiency has no metabolic consequences. Other gene targeting experiments have shown Gnas to have 2 independent imprinting domains controlled by 2 different imprinting control regions. Tissue-specific G(s)alpha knockout models have identified important roles for G(s)alpha signaling pathways in skeletal development, renal function, and glucose and lipid metabolism. Our present knowledge gleaned from various Gnas gene targeting models are discussed in relation to the pathogenesis of human disorders with mutation or abnormal imprinting of the human orthologue GNAS.
 ...
PMID:Studies of the regulation and function of the Gs alpha gene Gnas using gene targeting technology. 1758 69

Pseudopseudohypoparathyroidism (PPHP) is caused by the paternally-derived mutation in the coding region of GNAS gene. The phenotype of PPHP is produced by the sum of both decreased Gsalpha protein in biallelically expressed tissues and other proteins or non-coding RNAs by mutated paternal-allele specific expression. It has been believed that the haploinsufficiency of Gsalpha in non-imprinted tissues is responsible for the Albright hereditary dystrophy (AHO) phenotype. Recently it was reported that obesity is a more prominent feature in pseudohypoparathyroidism type I a than in PPHP. This result implicates paternal imprinting in the development of obesity in pseudohypoparathyroidism type I a. In this review, recent advances in clinical and experimental knowledge in genomic imprinting of GNAS gene were summarized.
 ...
PMID:[Pseudopseudohypoparathyroidism and genomic imprinting]. 1766 Jun 20

Pseudohypoparathyroidism type Ia (PHP-Ia), one of 4 types of PHP, is a genetic disease characterized by clinical hypoparathyroidism caused by parathyroid hormone (PTH) resistance. In addition, patients with PHP-Ia show resistance to other hormones as well as Albright's hereditary osteodystrophy (AHO), a constellation of features including short stature, obesity, brachydactyly, ectopic ossifications, and/or mental retardation. Hypocalcemia is one of the hallmarks of PHP-Ia, but several PHP-Ia patients have been described to have normocalcemia. We encountered a 10-year-old girl with typical Albright's hereditary osteodystrophy with round face, short stature, brachydactyly, and obesity. Biochemical examination showed normocalcemia and increased PTH levels. Ellsworth-Howard test did not show any responses of urinary cAMP and phosphate. Based on these findings, she was diagnosed as having PHP-Ia with normocalcemia. Sequencing analysis of the GNAS gene identified a heterozygous missense mutation in exon 13 (R385H), which was previously reported in a PHP-Ia patient. The exact reason for her normocalcemia is not determined, but we must recognize heterogeneous biochemical findings even in PHP-Ia.
 ...
PMID:A pseudohypoparathyroidism type Ia patient with normocalcemia. 1825 May 41

In mice, heterozygous knockout of the stimulatory G protein Gas results in obesity which suggests a key role of Gas in body weight regulation. We have recently identified a functional G(-1211)A promoter polymorphism in the human GNAS gene encoding Gas, the GG genotype being associated with increased promoter activity and lipolysis in vitro and increased weight loss capacity in vivo. The present study aimed to independently confirm these results. We genotyped 87 subjects who underwent a 7-day modified fast for the GNAS polymorphism and recorded weight, hunger, and mood. While both mood and hunger were not dependent on genotype, GNAS genotypes were significantly associated with weight loss (GG: -5.0 +/- 1.5 kg, n = 28; AG: -4.2 +/- 1.1 kg, n = 50; AA: -3.2 +/- 1.2, n = 9; p = 0.0003). The present study reconfirms our earlier reported findings and suggests that GNAS genotypes also influence weight loss during short-term fasting. related to a low vascular density (CD31 expression) in CDC.
 ...
PMID:A functional GNAS promoter polymorphism is associated with altered weight loss during short-term fasting. 1907 98

Albright hereditary osteodystrophy (AHO), also known as Martin-Albright syndrome (MAS), is a rare autosomal dominantly transmitted disease characterized by short stature, obesity, mental retardation, a round facies, and brachymetacarpia and -tarsia, as well as cutaneous calcification. The disease is caused by mutations in the GNAS gene localized on chromosome 20q13.2 encoding for an adenyl-cyclase-stimulating protein (Gsalpha). A 58-year-old patient presented with small stature since childhood, moderate mental retardation, round facies and soft tissue masses on the thighs. A biopsy of the latter showed subcutaneous ossification. Laboratory results showed hypocalcemia, as well as increased plasma levels of PTH and calcitonin. The clinical diagnosis was confirmed by detection of reduced activity of Gsalpha. In patients with cutaneous calcification and disturbed calcium metabolism, AHO is an important differential diagnostic consideration.
 ...
PMID:First diagnosis of Martin-Albright syndrome in a 58-year-old patient. 1913 95

Genomic imprinting is an epigenetic phenomenon affecting a small number of genes, which leads to differential expression from the two parental alleles. Imprinted genes are known to regulate fetal growth and a 'kinship' or 'parental conflict' model predicts that paternally and maternally expressed imprinted genes promote and inhibit fetal growth, respectively. In this review we examine the role of imprinted genes in postnatal growth and metabolism, with an emphasis on the GNAS/Gnas locus. GNAS is a complex imprinted locus with multiple oppositely imprinted gene products, including the G-protein alpha-subunit G(s)alpha that is expressed primarily from the maternal allele in some tissues and the G(s)alpha isoform XLalphas that is expressed only from the paternal allele. Maternal, but not paternal, G(s)alpha mutations lead to obesity in Albright hereditary osteodystrophy. Mouse studies show that this phenomenon is due to G(s)alpha imprinting in the central nervous system leading to a specific defect in the ability of central melanocortins to stimulate sympathetic nervous system activity and energy expenditure. In contrast mutation of paternally expressed XLalphas leads to opposite metabolic effects in mice. Although these findings conform to the 'kinship' model, the effects of other imprinted genes on body weight regulation do not conform to this model.
 ...
PMID:The role of GNAS and other imprinted genes in the development of obesity. 1984 12


1 2 3 4 Next >>