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.

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.

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.