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Background: We aimed to analyze hypertension in neurofibromatosis type 1 (NF1) in a Finnish population‐based cohort in 1996–2014. Methods: A cohort of 1365 individuals with confirmed NF1 was compared with a control cohort of 13,923 individuals matched for age, sex, and area of residence. Diagnoses of hypertension were retrieved from the Finnish Care Register for Health Care. These registered data were separately analyzed for secondary and essential hypertension. Purchases of antihypertensive drugs were queried from the Finnish Register of Reimbursed Drug Purchases. Results: We identified 115 NF1 patients with hospital diagnosis of hypertension. Our findings revealed a hazard ratio (HR) of 1.64 (95% CI 1.34–2.00, p < 0.001) in NF1 versus controls. NF1 patients presented with a significantly increased hazard for both secondary hypertension (n = 9, HR 3.76, 95% CI 1.77–7.95, p < 0.001) and essential hypertension (n = 98, HR 1.73, 95% CI 1.39–2.14, p < 0.001). No difference in the HR of hypertension was observed between men and women, while NF1 patients with essential hypertension were, on average, younger than the controls. The proportions of individuals with antihypertensive medication did not differ between NF1 patients and controls (OR 0.85). Conclusion: NF1 is a risk factor for hypertension. Despite the recognized risk for secondary hypertension, essential hypertension is the predominant type in NF1. [ABSTRACT FROM AUTHOR]

Background: Cutaneous neurofibromas (cNFs) are hallmarks of neurofibromatosis 1 (NF1) and cause the main disease burden in adults with NF1. Mast cells are a known component of cNFs. However, no comprehensive characterization of mast cells in cNFs is available, and their contributions to cNF growth and symptoms such as itch are not known. Methods: We collected 60 cNFs from ten individuals with NF1, studied their mast cell proteinase content, and compared the mast cell numbers to selected clinical features of the tumors and patients. The tumors were immunolabeled for the mast cell markers CD117, tryptase, and chymase, and the percentage of immunopositive cells was determined using computer-assisted methods. Results: The median proportions of positive cells were 5.5% (range 0.1–14.4) for CD117, 4.0% (1.2–7.0) for tryptase, and 5.0% (1.1–15.9) for chymase. The median densities of cells immunopositive for CD117, tryptase, and chymase were 280, 243, and 250 cells/mm2, respectively. Small tumors, growing tumors, and tumors from patients below the median age of 33 years displayed a high proportion of mast cells. Cells expressing both tryptase and chymase were the predominant mast cell type in cNFs, followed by cells expressing chymase only. Conclusion: The results highlight the abundance of mast cells in cNFs and that their number and subtypes clearly differ from those previously reported in unaffected skin. [ABSTRACT FROM AUTHOR]

Background The hereditary predisposition to diabetes is only partially explained by genes identified so far. Neurofibromatosis type 1 (NF1) is a rare monogenic dominant syndrome caused by aberrations of the NF1 gene. Here, we used a cohort of 1410 patients with NF1 to study the association of the NF1 gene with type 1 (T1D) and type 2 diabetes (T2D). Methods A total of 1410 patients were confirmed to fulfil the National Institutes of Health diagnostic criteria for NF1 by individually reviewing their medical records. The patients with NF1 were compared with 14 017 controls matched for age, sex and area of residence as well as 1881 non-NF1 siblings of the patients with NF1. Register-based information on purchases of antidiabetic medication and hospital encounters related to diabetes were retrieved. The Cox proportional hazards model was used to calculate the relative risk for diabetes in NF1. Results Patients with NF1 showed a lower rate of T2D when compared with a 10-fold control cohort (HR 0.27, 95% CI 0.17 to 0.43) or with their siblings without NF1 (HR 0.28, 95% CI 0.16 to 0.47). The estimates remained practically unchanged after adjusting the analyses for history of obesity and dyslipidaemias. The rate of T1D in NF1 was decreased although statistically non-significantly (HR 0.58, 95% CI 0.27 to 1.25). Conclusion Haploinsufficiency of the NF1 gene may protect against T2D and probably T1D. Since NF1 negatively regulates the Ras signalling pathway, the results suggest that the Ras pathway may be involved in the pathogenesis of diabetes. [ABSTRACT FROM AUTHOR]

Background: An increased breast cancer incidence and poor survival have been reported for women with neurofibromatosis 1 (NF1). To explain the poor survival, we aimed to link the histopathology and clinical characteristics of NF1-associated breast cancers.Methods: The Finnish Cancer Registry and the Finnish NF Registry were cross-referenced to identify the NF1 patients with breast cancer. Archival NF1 breast cancer specimens were retrieved for histopathological typing and compared with matched controls.Results: A total of 32 breast cancers were diagnosed in 1404 NF1 patients during the follow-up. Women with NF1 had an estimated lifetime risk of 18.0% for breast cancer, and this is nearly two-fold compared with that of the general Finnish female population (9.74%). The 26 successfully retrieved archival NF1 breast tumours were more often associated with unfavourable prognostic factors, such as oestrogen and progesterone receptor negativity and HER2 amplification. However, survival was worse in the NF1 group (P=0.053) even when compared with the control group matched for age, diagnosis year, gender and oestrogen receptor status. Scrutiny of The Cancer Genome Atlas data set showed that NF1 mutations and deletions were associated with similar characteristics in the breast cancers of the general population.Conclusions: These results emphasise the role of the NF1 gene in the pathogenesis of breast cancer and a need for active follow-up for breast cancer in women with NF1. [ABSTRACT FROM AUTHOR]

Dermal neurofibromas are the hallmarks of neurofibromatosis type 1 (NF1). Neurofibromas harbor Schwann cells with two different genotypes: Schwann cells which carry the germline mutation and a healthy NF1 allele (NF1+/−), and a subpopulation of Schwann cells which harbor the so-called second hit leading to inactivation of both NF1 alleles (NF1−/−). The second hit in the NF1 gene of Schwann cells is considered to be the initial step in the development of neurofibromas. Dermal neurofibromas typically start to grow in puberty, and their number and size increase during pregnancy, indicating hormone responsiveness. This is the first study to address the effect of human chorionic gonadotropin (hCG) on the proliferation of human NF1+/− and NF1−/− Schwann cells in vitro. In addition, the effects of estradiol and testosterone were also investigated. The results showed that NF1−/− Schwann cells were more sensitive to estradiol, testosterone, and human chorionic gonadotropin than NF1+/− cells. Specifically, the proliferation of NF1−/− Schwann cells was increased by up to 99, 110, and 170% compared to vehicle control when treated with estradiol, testosterone, and hCG, respectively. Interestingly, no effect of estradiol, testosterone, or hCG on the proliferation of the cells with NF1+/− genotype was observed. To conclude, the somatic second hit in the NF1 gene sensitizes Schwann cells to sex hormones resulting in a highly increased proliferation. Our results highlight the significance of sex hormones in the regulation of neurofibroma growth. [ABSTRACT FROM AUTHOR]

Neurofibromatosis 1 (NF1) occurs in 1:2000 births. The main diagnostic signs are visible on the skin, and this opens several interesting aspects for dermatological point of view. The NF1 syndrome is caused by mutations in the NF1 gene which encodes the tumor suppressor protein neurofibromin. Neurofibromin functions as a Ras-GTPase-activating protein (RasGAP), and NF1 mutations lead to overactivation of the Ras signalling pathway. The NF1 gene and neurofibromin have intriguing functions in keratinocytes and melanocytes. Neurofibromin regulates melanin synthesis and keratinocyte differentiation in a currently unknown manner. The NF1 gene has also an important but poorly understood role in tumorigenesis and cancer. Compared to the general population, NF1 patients have a fivefold risk for cancer and a more than 2000-fold risk for neurogenic malignancies. Mutations of the NF1 gene are common in numerous cancer types in patients without NF1, and this suggests a more general role for the NF1 gene in oncogenesis. In melanoma, NF1 mutations seem to drive tumorigenesis and contribute to drug resistance. In this article, we review the literature on neurofibromin with special attention to keratinocytes, melanocytes, NF1-related tumors and melanoma. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 1 syndrome (NF1) is caused by mutations in the NF1 gene. Availability of new sequencing technology prompted us to search for an alternative method for NF1 mutation analysis. Genomic DNA was isolated from saliva avoiding invasive sampling. The NF1 exons with an additional 50bp of flanking intronic sequences were captured and enriched using the SeqCap EZ Choice Library protocol. The captured DNA was sequenced with the Roche/454 GS Junior system. The mean coverages of the targeted regions were 41 x and 74 x in 2 separate sets of samples. An NF1 mutation was discovered in 10 out of 16 separate patient samples. Our study provides proof of principle that the sequence capture methodology combined with high-throughput sequencing is applicable to NF1 mutation analysis. Deep intronic mutations may however remain undetectable, and change at the DNA level may not predict the outcome at the mRNA or protein levels. [ABSTRACT FROM AUTHOR]

Abstract: Prolyl oligopeptidase (POP) may be associated with neuromodulation and development of neurodegenerative diseases and it was recently shown to participate in the inflammatory cascade along with matrix metalloproteinases. Radiotracers, which can be used for non-invasive imaging, are needed for investigating the role of POP in normal physiology and in pathophysiological conditions in vivo. We synthesized two novel POP-specific 123I-radiolabeled 4-phenylbutanoyl-l-prolyl-pyrrolidines of which 4-(4-[123I]iodophenyl)butanoyl-l-prolyl-2(S)-cyanopyrrolidine ([123I]2f, K i = 4.2 nM) was selected. The selected compound has an electrophilic cyano group that is known to increase the dissociation time of POP inhibitors. [123I]2f was synthesized in high radiochemical yield and purity (87 ± 4%, >99%, respectively) and with a specific activity of 456 ± 98 GBq/μmol. [123I]2f was evaluated in healthy mice (C57Bl/6JRccHsd) by ex vivo biodistribution studies and SPECT imaging. Pretreatment with the known inhibitor 4-phenylbutanoyl-l-prolyl-(2S)-cyanopyrrolidine (KYP-2047, 2d, K i = 0.023 nM) showed that binding of [123I]2f was POP specific. In addition, [123I]2f was evaluated in models of neuroinflammation and acute localized inflammation. A minor increase in binding of [123I]2f was observed in the inflamed region in the acute localized inflammation model. Similar increase in binding was not observed in the neuroinflammation model. [Copyright &y& Elsevier]

Various forms of oral involvement have been reported in patients with neurofibromatosis 1 (NF1). Here, we analyze register-based associations between NF1 and hospital visits related to oral infections. The Finnish NF1 cohort encompasses all individuals with verified NF1 who have visited the Finnish central and university hospitals in 1987-2011. The Finnish Care Register for Health Care allowed the follow-up of 1349 individuals with NF1, their 1894 siblings without NF1, and 13,870 matched controls for diagnoses related to oral infections in 1998-2014. We observed clearly increased hazards for hospital visits associated with dental caries (ICD-10 K02; NF1 vs. controls, hazard ratio [HR] 4.42, 95% CI 3.23-6.04), diseases of pulp and periapical tissues (K04; HR 3.85, 95% CI 2.68-5.54), and gingivitis and periodontal diseases (K05; HR 3.63, 95% CI 2.37-5.56). In contrast, hospital visits related to diseases of salivary glands (K11), and stomatitis and related lesions (K12) did not show significantly increased hazard in NF1 compared with the controls or the non-NF1 siblings. In conclusion, the findings suggest that hospital visits related to oral infections are relatively common among individuals with NF1. The results highlight the need for early detection, proactive prevention, and timely treatment of oral infections in individuals with NF1., (© 2024 The Author(s). American Journal of Medical Genetics Part A published by Wiley Periodicals LLC.)