Frequency of GNAS R201H substitution mutation in polyostotic fibrous dysplasia: Pyrosequencing analysis in tissue samples with or without decalcification

Molecular Dynamics Simulation of Kir6.2 Variants Reveals Potential Association with Diabetes Mellitus

Diabetes mellitus (DM) represents a problem for the healthcare system worldwide. DM has very serious complications such as blindness, kidney failure, and cardiovascular disease. In addition to the very bad socioeconomic impacts, it influences patients and their families and communities. The global costs of DM and its complications are huge and expected to rise by the year 2030. DM is caused by genetic and environmental risk factors. Genetic testing will aid in early diagnosis and identification of susceptible individuals or populations using ATP-sensitive potassium (KATP) channels present in different tissues such as the pancreas, myocardium, myocytes, and nervous tissues. The channels respond to different concentrations of blood sugar, stimulation by hormones, or ischemic conditions. In pancreatic cells, they regulate the secretion of insulin and glucagon. Mutations in the KCNJ11 gene that encodes the Kir6.2 protein (a major constituent of KATP channels) were reported to be associated with Type 2 DM, neonatal diabetes mellitus (NDM), and maturity-onset diabetes of the young (MODY). Kir6.2 harbors binding sites for ATP and phosphatidylinositol 4,5-diphosphate (PIP2). The ATP inhibits the KATP channel, while the (PIP2) activates it. A Kir6.2 mutation at tyrosine330 (Y330) was demonstrated to reduce ATP inhibition and predisposes to NDM. In this study, we examined the effect of mutations on the Kir6.2 structure using bioinformatics tools and molecular dynamic simulations (SIFT, PolyPhen, SNAP2, PANTHER, PhD&SNP, SNP&Go, I-Mutant, MuPro, MutPred, ConSurf, HOPE, and GROMACS). Our results indicated that M199R, R201H, R206H, and Y330H mutations influence Kir6.2 structure and function and therefore may cause DM. We conclude that MD simulations are useful techniques to predict the effects of mutations on protein structure. In addition, the M199R, R201H, R206H, and Y330H variant in the Kir6.2 protein may be associated with DM. These results require further verification in protein-protein interactions, Kir6.2 function, and case-control studies.

Benign tumors of the chest wall

Benign tumors of the chest wall are rare tumors that might arise from all the tissues of the chest: vessels, nerves, bones, cartilage, and soft tissues. Despite benign features, these tumors can have several histological characteristics and different behaviors. Even if they do not influence life expectancy, rarely they may have a potential risk of malignant transformation. They can cause several, oft, unspecific symptoms but more than 20% of affected patients are asymptomatic and are being diagnosed incidentally on chest radiograph or computed tomography scan. Pain is the most common described symptom. Together with a detailed medical history, a rigorous and meticulous clinical and radiological assessment is mandatory. If radiological features are unclear or in case surgery could not be performed, a biopsy should be indicated to establish a diagnosis. Radical surgical resection can often be offered to resect and cure these neoplasms, but this is might not be true for all types of tumors and, in some cases, their dimension or position might contra-indicate surgery. Given the rarity of these tumors, there is a lack of treatment's guidelines and prospective trials that include a significant number of patients. This review discusses, according to the latest evidence, the histological features and the best treatment of several chest wall benign tumors.

Identification of GNAS Variants in Circulating Cell-Free DNA from Patients with Fibrous Dysplasia/McCune Albright Syndrome

Fibrous dysplasia/McCune-Albright syndrome (FD/MAS) is a rare mosaic bone and endocrine disorder. Although most variants affect the GNAS R201 codon, obtaining a genetic diagnosis is difficult because not all cells harbor the variant, and an invasive biopsy may be required. We explored the presence of GNAS p.R201 variants in blood circulating cell free DNA (ccfDNA) using sensitive techniques of digital droplet polymerase chain reaction (PCR) (ddPCR) and competitive allele-specific TaqMan PCR (castPCR) in an effort to improve the genetic diagnosis of FD/MAS. We isolated ccfDNA from the plasma of 66 patients with a wide range of disease severity and performed both ddPCR and castPCR mutation analysis to search for GNAS p.R201H or R201C variants. We detected R201 variants in ccfDNA samples of 41 of 66 (62.1%) patients by either castPCR or ddPCR, and 45 of 66 (68.2%) of patients if the techniques were combined. Variant detection was more likely in patients with more severe disease. Skeletal disease burden score (SBS) was significantly higher in patients who had detectable variants, and SBS was a predictor of variant allele frequency. By ddPCR analysis, patients aged ≤30 years had higher detection rates, and higher variant allele frequencies, independent of disease burden. We detected variant DNA in only one patient with monostotic FD by ddPCR only. In summary, we have demonstrated that ccfDNA containing variant GNAS can be isolated from the plasma of patients with FD/MAS and that ddPCR and castPCR methods have similar variant detection rates. This methodology represents an important potential advancement in diagnosis for patients with FD/MAS, especially those younger than 30 years or with more severe disease. Published 2023. This article is a U.S. Government work and is in the public domain in the USA.

GNAS mutation analysis assists in differentiating chronic diffuse sclerosing osteomyelitis from fibrous dysplasia in the jaw

Chronic diffuse sclerosing osteomyelitis of the mandible (DSOM) and fibrous dysplasia (FD) are distinct lesions with overlapping clinicopathological features that complicate their diagnosis. This study aimed to evaluate the efficacy of GNAS mutation analysis in differentiating between these two conditions. DNA samples from patients with DSOM (n = 35) and FD (n = 29) were collected to analyze the presence of GNAS mutations in exons 8 and 9, the two previously reported hotspot regions, using polymerase chain reaction and direct sequencing. Twenty-four of 29 patients (83%) with FD showed missense mutations in codon 201 in exon 8, whereas no mutation was detected in exon 9. No mutations were found in any of the 35 cases with DSOM. We also identified one case with an uncertain diagnosis due to overlapping clinicopathological features of DSOM and FD. A Q227H mutation was detected in this case, that confirmed the diagnosis of FD. Taken together, the findings indicate that mutational analysis of the GNAS is a reliable approach to differentiate between DSOM and FD of the jaw.

Effect of decalcification protocols on immunohistochemistry and molecular analyses of bone samples

Diagnosis of osteocartilaginous pathologies depends on morphological examination and immunohistochemical and molecular biology analyses. Decalcification is required before tissue processing, but available protocols often lead to altered proteins and nucleic acids, and thus compromise the diagnosis. The objective of this study was to compare the effect of different methods of decalcification on histomolecular analyses required for diagnosis and to recommend an optimal protocol for processing these samples in routine practice. We prospectively submitted 35 tissue samples to different decalcification procedures with hydrochloric acid, formic acid, and EDTA, in short, overnight and long cycles for 1 to >10 cycles. Preservation of protein integrity was examined by immunohistochemistry, and quality of nucleic acids was estimated after extraction (DNA and RNA concentrations, 260/280 ratios, PCR cycle thresholds), analysis of DNA mutations (high-resolution melting) or amplifications (PCR, in situ hybridization), and detection of fusion transcripts (RT-PCR, in situ hybridization). Hydrochloric acid- and long-term formic acid-based decalcification induced false-negative results on immunohistochemistry and molecular analysis. EDTA and short-term formic acid-based decalcification (<5 cycles of 6 h each) did not alter antigenicity and allowed for detection of gene mutations, amplifications or even fusion transcripts. EDTA showed superiority for in situ hybridization techniques. According to these results and our institutional experience, we propose recommendations for decalcification of bone samples, from biopsies to surgical specimens.

Multi-analytic study of a probable case of fibrous dysplasia (FD) from certosa monumental cemetery (Bologna, Italy)

OBJECTIVE

To evaluate, via a multidisciplinary approach, a distinctive paleopathological condition believed to be fibrous dysplasia, found on a 19th/20th century skeleton from Certosa Monumental Cemetery, Bologna, Italy.

MATERIALS

A skeletonized cranium and mandible recovered from an ossuary in 2014.

METHODS

Pathological alterations were analysed by radiological examination, dental macrowear, histopathological and genetic analyses.

RESULT

The skeleton is believed to be an adult male. Differential diagnoses include Paget's disease, McCune-Albright syndrome, osteochondroma and osteosarcoma. The radiographic findings, along with the solitary nature of the lesions, are strong evidence for the diagnosis of fibrous dysplasia (FD). Genetic analysis further revealed a frequency of ˜1% of mutant alleles with the R201C substitution, one of the post-zygotic activating mutation frequently associated with FD.

CONCLUSIONS

The multi-analytical method employed suggests a diagnosis of monostotic form of FD. The diagnostic design incorporates multiple lines of evidence, including macroscopic, histopathological, and genetic analyses.

SIGNIFICANCE

Through the use of a multi-analytic approach, robust diagnoses can be offered. This case serves as one of the oldest examples of FD from an historical context. The genetic mutation detected, associated with FD, has not been previously reported in historical/ancient samples.

Co-administration of Systemic and Intralesional Zoledronic Acid in a Case of Fibrous Dysplasia: A Potentially Novel Therapy

Fibrous dysplasia (FD) is a benign bone lesion characterized by replacement of normal bone with abnormal fibrous tissue, clinically manifesting as deformities, bone pains, and pathological fractures. The standard medical management for FD includes systemic bisphosphonate therapy. The efficacy of systemic bisphosphonate is however limited with minimal functional improvement and pain relief. Keeping the above lacunae in mind, we have made a solitary attempt at treating FD with locally administered zoledronic acid. A 25-year-old gentleman had presented to our institute with swelling and pain involving the left thigh and left lower leg. He was diagnosed as having polyostotic FD, confirmed on bone histopathology. He was administered 4 mg of zoledronic acid intravenously while 1 mg of the drug was injected locally into the femoral lesion under ultrasound and fluoroscopy guidance. There were no peri-procedural complications. At 6 months follow-up, there was marked improvement in pain scores at the left thigh, while that at the left leg remained unchanged. In addition, repeat bone scintigraphy showed a 20.8% and 25.3% reduction in anterior and posterior uptake values, respectively, at the left femur while that at the left tibia remained unaltered.

Head and neck manifestations of an undiagnosed McCune-Albright syndrome: clinicopathological description and literature review

Craniofacial fibrous dysplasia, characteristic of McCune-Albright syndrome (MAS), is usually present in patients with MAS-related acromegaly. We report here the first case of a patient with an undiagnosed MAS presenting with an acute hydrocephalus. A 21-year-old male with gigantism and craniofacial fibrous dysplasia consulted for rapidly progressive headache. An acute obstructive hydrocephalus due to a 39 × 35-mm cystic lesion in the third ventricle was discovered and operated, obtaining hydrocephalus resolution. Pathology described a colloid cyst material and a growth hormone-secreting pituitary adenoma. Genetic study revealed the mosaic GNAS R201H mutation in the pituitary tissue, confirming a MAS diagnosis. Adequate hormonal control was achieved postoperatively. Our results suggest that long-term untreated growth hormone excess in patients with MAS-related craniofacial fibrous dysplasia might end compromising cerebrospinal fluid flow. A prompt diagnosis and coordinated multidisciplinary treatment may help to avoid long-term deleterious impact of hyperfunctioning endocrinopathies in these patients.

Fibrous dysplasia imitating malignancy

Fibrous dysplasia is a benign bone disease, presenting as monostotic or polyostotic lesions, or as part of a syndrome (McCune-Albright/Mazabraud). Its clinical course shows a variegated picture and the progression of its growth is unpredictable. In the workup of 39 fibrous dysplasia cases in the cranio-facial area, four cases presented fast growth tendencies, of which two patients with McCune-Albright syndrome showed malignant-like rapid growth. This local aggressive form is extremely rare, and the concept of this issue has not been clearly defined. With regard to the speed of growth a volumetric-time analysis in one of our cases demonstrated a 74 days tumor doubling rate with an exponential growth curve. According to the literature the aggressive form presented extra-cranially mainly at an adult age, whereas its appearance in our cranio-facial patient collective was much younger. Distinguishing nonmalignant and malignant aggressive forms is difficult and highly inconsistent in the literature. We therefore implemented a quantitative growth measure analysis to define aggressive forms based on progression and speed of growth and impartial of type of FD, localization or functional incapacity. Due to our study findings and literature review we state a prevalence of an aggressive form might be possibly about 5 %.