1/6. osteosarcoma in a patient with McCune-Albright syndrome and Mazabraud's syndrome: a case report emphasizing the cytological and cytogenetic findings.Osteosarcomatous transformation in fibrous dysplasia is unusual. The incidence is increased in patients with concomitant Mazabraud's syndrome and McCune-Albright syndrome. We report the cytological, histological, and cytogenetic findings of this rare entity arising from a mass in the right elbow of a 44-year-old African-American woman. The fine-needle aspiration (FNA) findings were diagnostic of malignancy, with markedly atypical spindle and polygonal cells admixed with osteoid. The diagnosis of osteosarcoma by FNA was subsequently further confirmed by histological evaluation of an above-elbow amputation specimen. fluorescence in situ hybridization and comparative genomic hybridization demonstrated trisomies of chromosomes 5 and 7 in the fibrous dysplasia and osteosarcoma. In addition, multiple chromosomal abnormalities were also noted in the osteosarcoma. We are unaware of any previous reports of the cytogenetic findings in the tissue of this rare condition, and argue for the value of FNA in the evaluation of such patients under selected conditions.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
2/6. Molecular delineation of deletions on 2q37.3 in three cases with an Albright hereditary osteodystrophy-like phenotype.A minority of the reported cases of terminal 2q37 deletion clinically resemble Albright hereditary osteodystrophy (AHO)/pseudopseudohypoparathyroidism and have only mild-to-moderate mental retardation. Our molecular and cytogenetic fluorescence in situ hybridization (FISH) findings on an additional three patients further reduce the size of the minimal critical region deleted in this syndrome to about 3 Mb. This region includes the G-protein-coupled receptor 35 (GPR35), glypican 1 (GPC1), and serine/threonine protein kinase 25 (STK25) genes on 2q37.3. We have further defined several polymorphic variants within the coding region and flanking regions of GPR35 gene, which could potentially be useful for rapid detection of GPR35 gene deletion. We postulate that the absence of GPR35 may, at least partly, account for the phenotypic resemblance to the AHO. We also believe that the deletion of GPR35 could be responsible for the entity brachydactyly mental retardation syndrome (OMIM #600430), which was coined based on the above minority of patients with terminal 2q37 deletion. We recommend that every patient with AHO phenotype should undergo 2q subtelomeric FISH screen and subsequently a molecular study on the GPR35 gene. GPC1 and/or STK25 haploinsufficiency may also contribute to the AHO-like phenotype.- - - - - - - - - - ranking = 0.5keywords = hybridization (Clic here for more details about this article) |
3/6. Two further AHO-like syndrome patients with deletion of glypican 1 gene region in 2q37.2-q37.3.In this report, we describe two unrelated patients with mental retardation and brachydactyly E classified as patients suffering from Albright hereditary osteodystrophy-like (AHO-like) syndrome. fluorescence in situ hybridization (FISH) analysis using 8 different subtelomeric probes in 2q36-37 proved that the patients had subtelomeric 2qter deletions of similar size. The recently proposed candidate gene glypican 1 (GPC1) is deleted in both reported patients.- - - - - - - - - - ranking = 0.5keywords = hybridization (Clic here for more details about this article) |
4/6. Activating mutations of the stimulatory G protein in the McCune-Albright syndrome.BACKGROUND. The McCune-Albright syndrome is a sporadic disease characterized by polyostotic fibrous dysplasia, cafe au lait spots, sexual precocity, and hyperfunction of multiple endocrine glands. These manifestations may be explained by a somatic mutation in affected tissues that results in activation of the signal-transduction pathway generating cyclic amp (cAMP). We analyzed dna from tissues of patients with the McCune-Albright syndrome for the presence of activating mutations of the gene for the alpha subunit of the G protein (Gs alpha) that stimulates cAMP formation. methods. Genomic dna fragments encompassing regions (exons 8 and 9) previously found to contain activating missense mutations of the Gs alpha gene (gsp mutations) in sporadically occurring pituitary tumors were amplified in tissues from four patients with the McCune-Albright syndrome by the polymerase chain reaction. The amplified dna was analyzed for mutations by denaturing gradient gel electrophoresis and allele-specific oligonucleotide hybridization. RESULTS. We detected one of two activating mutations within exon 8 of the Gs alpha gene in tissues from all four patients, including affected endocrine organs (gonads, adrenal glands, thyroid, and pituitary) and tissues not classically involved in the McCune-Albright syndrome. In two of the patients, histidine was substituted for arginine at position 201 of Gs alpha, and in the other two patients cysteine was substituted for the same arginine residue. In each patient the proportion of cells affected varied from tissue to tissue. In two endocrine organs, the highest proportion of mutant alleles was found in regions of abnormal cell proliferation. CONCLUSIONS. Mutations within exon 8 of the Gs alpha gene that result in increased activity of the Gs protein and increased cAMP formation are present in various tissues of patients with the McCune-Albright syndrome. Somatic mutation of this gene early in embryogenesis could result in the mosaic population of normal and mutant-bearing tissues that may underlie the clinical manifestations of this disease.- - - - - - - - - - ranking = 0.5keywords = hybridization (Clic here for more details about this article) |
5/6. An activating Gs alpha mutation is present in fibrous dysplasia of bone in the McCune-Albright syndrome.McCune-Albright syndrome (MAS) is a sporadic disease characterized by polyostotic fibrous dysplasia, cafe-au-lait spots, and multiple endocrinopathies. The etiology of fibrous dysplasia is unknown. Activating mutations of codon 201 in the gene encoding the alpha-subunit of Gs, the G-protein that stimulates adenylyl cyclase, have been found in all affected MAS tissues that have been studied. Initial attempts to amplify dna from decalcified paraffin-embedded bone specimens from MAS patients were unsuccessful. Therefore, we analyzed dna from frozen surgical bone specimens from five MAS patients using polymerase chain reaction and allele-specific oligonucleotide hybridization. Most of the cells in four specimens of dysplastic bone contained a heterozygous mutation encoding substitution of Arg201 of Gs alpha with His, but the mutation was barely detectable in peripheral blood specimens from the patients. Only a small amount of mutant allele was detected in a specimen of normal cortical bone from the fifth patient, although this patient had a high proportion of mutation in other, affected tissues. The mosaic distribution of mutant alleles is consistent with an embryological somatic cell mutation of the Gs alpha gene in MAS. The presence of an activating mutation of Gs alpha in osteoblastic progenitor cells may cause them to exhibit increased proliferation and abnormal differentiation, thereby producing the lesions of fibrous dysplasia.- - - - - - - - - - ranking = 0.5keywords = hybridization (Clic here for more details about this article) |
6/6. Primary hyperparathyroidism-associated polyostotic fibrous dysplasia: absence of McCune-Albright syndrome mutations.Several cases of sporadic primary hyperparathyroidism in association with fibrous dysplasia of the bone have been reported in the English literature. Since fibrous dysplasia is a major feature and hyperparathyroidism is occasionally found in the McCune-Albright syndrome, we hypothesized that such cases may represent a variant of this syndrome. A 28-year-old male had primary hyperparathyroidism associated with polyostotic fibrous dysplasia but no other manifestations of the McCune-Albright syndrome. Genomic dna samples from his parathyroid adenoma, dysplastic bone sample, and peripheral leukocytes were analyzed for the presence of activating mutations of the stimulating G protein alpha subunit gene (gsp). Allele-specific hybridization revealed the presence of normal sequences only, coding for arginine and glutamine at codons 201 (exon 8) and 227 (exon 9), respectively. Further, single strand conformational analysis of a 224 base pair fragment of exon 8 revealed no conformational aberrations. Furthermore, the sequences of a 164 base pair fragment of exon 8 and a 170 base pair fragment of exon 9 were normal. The results strongly suggest that gsp mutation is absent in affected and normal tissues in this patient and that the association of hyperparathyroidism and fibrous dysplasia may not represent a variant of the McCune-Albright syndrome.- - - - - - - - - - ranking = 0.5keywords = hybridization (Clic here for more details about this article) |