G protein gene variants in schizophrenia

Abstract Background Various studies demonstrating enhanced vulnerability to apoptosis may contribute to the pathobiology of schizophrenia. Objective Thus, G proteins may provide an intriguing link between the signal transduction, and apoptotic hypotheses of schizophrenia. In the light of these findings, we investigated whether G protein gene polymorphisms (GNAS1-T393C and GNB3-C825T) accounted for an increased risk of schizophrenia. Methods The present analyses were based on 100 subjects diagnosed with schizophrenia, and on 100 unrelated healthy controls. The genotyping of GNAS1-T393C, and GNB3-C825T gene polymorphisms were performed using the polymerase chain reaction- restriction fragment length polymorphism (PCR-RFLP). Results: We demonstrated the positive association of GNB3-C825T gene variants with schizophrenia risk (p: 0.023). In our study, more prevalent CC genotype frequencies were detected in GNB3 in patients compared with the frequencies in the controls. The individuals with GNB3-C825T CC genotype had 2 fold increased risk for schizophrenia (p: 0.011, c2: 6.39, OR:2.14, 95% CI: 1.18-3.90). Discussion Our study results suggested that GNB3-C825T polymorphism might be associated with schizophrenia.

Study of major genetic factors involved in pituitary tumorigenesis and their impact on clinical and biological characteristics of sporadic somatotropinomas and non-functioning pituitary adenomas

Genetic and functional aberrations of guanine nucleotide-binding protein, alpha stimulating (GNAS), aryl hydrocarbon receptor interacting protein (AIP), and pituitary tumor transforming gene (PTTG) are among the most prominent events in pituitary tumorigenesis. A cohort of Brazilian patients with somatotropinomas (n=41) and non-functioning pituitary adenomas (NFPA, n=21) from a single tertiary-referral center were evaluated for GNAS and AIP mutations and gene expression of AIP and PTTG. Results were compared to the clinical and biological (Ki67 and p53 expression) characteristics of tumors and their response to therapy, if applicable. Genetic analysis revealed that 27% of somatotropinomas and 4.8% of NFPA harbored GNAS mutations (P=0.05). However, no differences were observed in clinical characteristics, tumor extension, response to somatostatin analog therapy, hormonal/surgical remission rates, Ki67 index, and p53 expression between mutated and non-mutated somatotropinomas patients. PTTG overexpression (RQ mean=10.6, min=4.39, max=11.9) and AIP underexpression (RQ mean=0.56, min=0.46-max=0.92) were found in virtually all cases without a statistically significant relationship with clinical and biological tumor features. No patients exhibited somatic or germline pathogenic AIP mutations. In conclusion, mutations in GNAS and abnormal PTTG and AIP expression had no impact on tumor features and treatment outcomes in this cohort. Our data support some previous studies and point to the need for further investigations, probably involving epigenetic and transcriptome analysis, to improve our understanding of pituitary tumor behavior.

Displasia fibrosa ósea / Fibrous dysplasia of bone

La displasia fibrosa ósea es un trastorno no hereditario del desarrollo esquelético caracterizado por una proliferación anormal de fibroblastos y diferenciación deficiente de osteoblastos que conduce a un reemplazo del tejido óseo esponjoso por tejido conectivo fibroso. Es producida por una mutación somática activadora del gen GNAS1 que induce una activación y proliferación de células mesenquimales indiferenciadas con formación de tejido fibroso y trabéculas óseas anómalas. Existen formas monostóticas, poliostóticas y craneofaciales con diversos grados de dolor, deformidades y fracturas óseas, aunque muchos casos son asintomáticos. En ocasiones se producen quistes óseos aneurismáticos, hemorragias, compromisos neurológicos y raramente osteosarcomas. Algunos casos se asocian a síndrome de McCune-Albright, síndrome de Mazabraud y a osteomalacia por hipofosfatemia por pérdida tubular renal inducida por el FGF23 producido por el tejido displásico. Los hallazgos en las radiografías convencionales son característicos, aunque variables y de carácter evolutivo. La gammagrafía ósea es la técnica de imagen con mayor sensibilidad para determinar la extensión de la enfermedad. El diagnóstico diferencial incluye múltiples lesiones óseas de características similares y en raras ocasiones se requiere biopsia ósea o estudio genético para confirmarlo. No existe un consenso unánime acerca del abordaje terapéutico de estos pacientes, razón por la cual es necesario un enfoque multidisciplinario. La conducta puede ser expectante o quirúrgica según el tipo de lesiones y es importante el manejo del dolor y de las endocrinopatías asociadas. La mayor experiencia publicada se refiere al uso de bifosfonatos y, más recientemente, denosumab. Los tratamientos actuales son insuficientes para modificar el curso de la enfermedad y es necesario el desarrollo de nuevas moléculas que actúen específicamente en el gen GNAS1 o sobre las células mesenquimales afectadas. (AU)

Fibrous dysplasia of bone is a noninherited developmental anomaly of bone characterized by abnormal proliferation of fibroblasts and differentiation of osteoblasts that cause a replacement of trabeculous bone by fibrous connective tissue. It is caused by a somatic mutation in the GNAS1 gene, which induces an undifferentiated mesenquimal cells activation and proliferation with formation of fibrous tissue and abnormal osseous trabeculae. There are monostotic, polyostotic and craniofacial variants with different grades of bone pain, deformities and fractures, although many cases remain asymptomatic. Aneurysmal bone cysts, bleeding, neurological compromise and infrequently osteosarcoma are possible complications. Some cases are associated to McCune-Albright syndrome, Mazabraud syndrome or hypophosphatemia and osteomalacia due to to renal tubular loss induced by FGF23 produced by dysplastic tissue. The findings on conventional radiography are characteristic although variable and evlolve with time. Bone scintigraphy is the most sensitive technique to evaluate the extent of disease. Differential diagnosis include several osseous lesions of similar appearance and, in some cases, bone biopsy or genetic testing may be necessary. Today, there is no consensus regarding the therapeutic approach for these patients and it is necessary a multidisciplinary medical team. Watchful waiting or surgical interventions can be indicated, depending on the type of bone lesions. Bone pain and associated endocrinopathies management are very important. Most published experience refers to the use of bisphosphonates and, more recently, denosumab. Current treatments are insufficient to modify the natural curse of the disease and therefore, new molecules with specific action on GNAS1 gene or affected mesenchymal cells are necessary. (AU)

Analysis of clinical features and related genes variation in 41 girls with McCune-Albright syndrome / 中华内分泌代谢杂志

Objective To investigate the clinical characteristics and molecular pathological mechanism of McCune-Albright syndrome ( MAS) in order to provide a guidance for the precision medicine of MAS. Method The clinical data and genetic findings of 41 patients with MAS were analyzed retrospectively. Results (1) MAS girls had the phenotype of peripheral precocious puberty with premature sexual development and high estradiol, low LH and FSH, and the increased volume of uterus and ovary. ( 2 ) In 41 MAS cases, there were 17 cases with GNAS1 gene mutation, and the total positive rate was 41. 5%, of which the classic triad was 66. 7%, two signs 56. 3%, and 12. 5% in only one classic sign. GNAS1 gene mutation was found in 78. 6% of patients with polyostotic fibrous dysplasia of bone, while only 55. 0% in patients with cafe au lait skin spots. Children with precocious puberty and fibrous dysplasia of bone is an important basis for clinical diagnosis of MAS, but cafe au lait skin spots does not seem to be the specifical manifestation of MAS. Conclusion Clinically MAS was lack of typical clinical manifestations, and the most important clinical weight factor for the diagnosis of MAS was peripheral precocious puberty with fibrous dysplasia of bone. GNAS1 gene screening may be helpful to improve the clinical accurate diagnosis of MAS.

A Case of GNAS1 Mutation in Pseudohypoparathyroidism Type Ia

Pseudohypoparathyroidism (PHP) is a group of genetic disorders in which the kidneys fail to respond to parathyroid hormone. Genetic defects in the GNAS complex locus lead to reduced Gsalpha (alpha-subunit of the heterotrimeric stimulatory G protein) activity in PHP type Ia patients. These patients exhibit characteristics of Albright hereditary osteodystrophy (AHO) and hypocalcemia, increased parathyroid hormone, and resistance to other Gsalpha protein-coupled hormones. AHO has a wide range of manifestations such as short stature, obesity, round face, subcutaneous ossification, and bone shortening in the hands and feet. In this study, we present the case of a 47-yr-old woman who was diagnosed with PHP type Ia with AHO. She showed tetany, dizziness, irritability to light, decreased visual acuity, cognitive impairment, and motor dysfunction. Direct sequencing identified a heterozygous missense mutation in exon 6 (c.466G>A, p.Asp156Asn) in GNAS1. To our knowledge, this case is the first report in Korea of PHP type Ia caused by a heterozygous missense mutation in exon 6 (c.466G>A, p.Asp156Asn) in GNAS1.

Progress of diagnosis and clinical management of pseudohypoparathyroidism / 中华实用儿科临床杂志

Pseudohypoparathyroidism(PHP) is a rare genetic disorder.The main character is parathyroid hormone resistance,and some with typical Albright's Hereditary Osteodystrothy malformation.The wide range of PHP symptom spectrum may lead to miss or misdiagnosis.This paper reviewed and summarized the pathogenesis,manifestation and the progress on the diagnosis and treatment of PHP Ⅰ,so as to improve the diagnostic level of this disease.

Analysis of promoter methylation of GNAS1 gene in pseudohypoparathyroidism type Ib / 中华内分泌代谢杂志

The methylation status of GNAS1 gene in pseudohypoparathyroidism type Ib patients was detected by methylation-specific PGR technique. There was an abnormal methylation of 1A region in all seven PHPIb patients. Loss of exon 1A methylation (imprinting defect) seems to be the cause of PHPIb.

A Case of McCune-Albright Syndrome with Associated Multiple Endocrinopathies

McCune-Albright syndrome (MAS) is a rare disorder that develops from an activating mutation in the Gs gene. It is characterized by an association with Polyostotic fibrous dysplasia, and precocious puberty, Caf-au-lait pigmentation, and other endocrinopathies that result from the hyperactivity of a variety of endocrine glands. Recently we encountered a patient with MAS with fibrous dysplasia, skin pigmentation, acromegaly, hyperprolactinemia and a thyroid nodule. A 23-year-old male presented for an evaluation of a change in his facial structures. Fibrous dysplasia was diagnosed by a bone biopsy and radiographic studies. The GH level increased paradoxically after an oral glucose load. The plasma prolactin, IGF-1 and alkaline phosphatase were high. Thyroid ultrasonography revealed multiple nodules. The brain MRI demonstrated a mass in the left pituitary gland. Genetic analysis identified a change from Arg (CGT) at codon 201 to Cys (TGT).

Mutational Analysis of Gsalpha Protein in Fibrous dysplasia of the Bone / 대한내분비학회지

BACKGROUND: Fibrous dysplasia of the bone(FD) is a benign fibrous bone lesion which usually involves the long bones of the extremities. FD may be asymptomatic, but often leads to bone deformity and pathological fracture. The disease is caused by a somatic mutation in the Gsalpha protein, which is responsible for intracellular signal transduction. METHODS: Mutations in the GNAS1 gene, which codes for Gsalpha protein, was investigated in 34 patients with monostotic and polyostotic FD and McCune-Albright syndrome. DNA was extracted from formalin-fixed, paraffin embedded bone tissues, and exons 8 and 9 of the GNAS1 gene amplified using a polymerase chain reaction(PCR). Subsequently, plasmid cloning and DNA sequencing analysis were performed. RESULTS: The PCR was successfully performed in 5 patients with monostotic FD. However, the sequencing analysis failed to identify any significant point mutations in exons 8 or 9 of GNAS1. Nevertheless, 3 point mutations were observed in the intron of the GNAS1 gene in 2 samples. CONCLUSION: In addition to the previously known somatic mutations of the GNAS1 gene, this study suggests that fibrous dysplasia of the bone might be associated with another point mutations of the GNAS1 gene