RET Proto-Oncogene Germline Mutation in Pheochromocytoma Patients - Incidence and Clinical Consequences

Wstęp Dotychczasowe badania wskazują, że częstość zespołu mnogiej gruczolakowatości (MEN 2), w skład którego wchodzi guz chromochłonny, jest większa niż dotychczas sądzono. Zespół ten dziedziczony jest w sposób autosomalny dominujący i wywołuje go mutacja protoonkogenu RET. Celem pracy jest ocena częstości występowania oraz kliniczne znaczenie mutacji protoonkogenu RET u chorych z guzem chromochłonnym. Materiał i metody Badania genetyczne w kierunku mutacji protoonkogenu RET przeprowadzono u 106 chorych (średni wiek: 49 ± 14,1 roku, 26M, 80K) z rozpoznanym i potwierdzonym histopatologicznie guzem chromochłonnym. Pacjenci ci byli uprzednio hospitalizowani i leczeni w Klinice Chorób Wewnętrznych i Nadciśnienia Tętniczego Akademii Medycznej w Warszawie w latach 1957–1998 oraz w Klinice Nadciśnienia Tętniczego Instytutu Kardiologii w Warszawie od roku 1980 do 2001. Oceniano również stężenie kalcytoniny (CT), zarówno w warunkach podstawowych, jak i po stymulacji pentagastryną, oraz stężenie parathormonu. Wyniki Obecność mutacji protoonkogenu RET wykazano u 8 chorych (7,4%) - w eksonie 11, w kodonie 634, TGC na CGC u 5 chorych, u pozostałych 3 odpowiednio - w eksonie 11, kodonie 634, TGC na GGC, w eksonie 11, kodonie 634, TGC na TGG oraz w eksonie 13, kodonie 791, TAT na CGC. Nadczynność komórek C potwierdzoną dodatnim testem pentagastrynowym stwierdzono u 5 nosicieli, u 2 chorych wynik testu był wątpliwy, jedynie u 1 chorego stężenie kalcytoniny było prawidłowe. Prawidłowe stężenie CT obserwowano u chorego z mutacją w eksonie 13, kodonie 791, TAT na CGC. U 4 nosicieli potwierdzono histopatologicznie obecność raka rdzeniastego tarczycy (biopsja cienkoigłowa). U 3 chorych wykonano totalną tyroidektomię, dwóch nie wyraziło zgody na dalsze leczenie (w tym jeden z pozytywnym wynikiem biopsji). Pozostali chorzy zostali poinformowani o konieczności totalnej tyroidektomii. U żadnego nosiciela nie stwierdzono nadczynności przytarczyc. Wnioski Wyniki badań autorów potwierdzają doniesienia o konieczności poddawania przesiewowym badaniom genetycznym oceniającym obecność mutacji protoonkogenu RET pacjentów z guzem chromochłonnym. Potwierdzenie nosicielstwa tej mutacji stanowi wskazanie do wykonania totalnej tyroidektomii. Genetyczne badania przesiewowe mogą mieć również znaczenie w wykrywaniu zespołu MEN 2 oraz ustaleniu dalszego postępowania u członków rodzin, u których stwierdza się mutację protoonkogenu RET.Background In patients with pheochromocytoma there may exist more often than expected the autosomal dominant cancer syndrome — multiple endocrine neoplasia type 2 (MEN 2). The susceptibility gene for MEN 2 is the RET proto-oncogene. Germline mutations can be identified by analysis of exons 10, 11, 13–16 of the RET gene. The aim of the study was to evaluate the frequency of these mutations in patients with pheochromocytoma and to report on the conclusions which patients and physicians have drawn. Material and methods We screened for germline mutations in the RET proto-oncogene and clinically evaluated 106 unselected patients with pheochromocytoma (mean age: 49 ± 14,1 years, 26 male, 80 female) histopathologically confirmed, diagnosed and treated in the years 1957–1998 in the Department of Internal Medicine and Hypertension, Warsaw School of Medicine and in the years 1980/81–2001 in the Department of Hypertension, Institute of Cardiology, Warsaw. Determination of calcitonin concentration (CT) was performed in basal conditions and after pentagastrin stimulation; parathormone level was also determined. Results Genetic testing revealed germline mutations in the RET proto-oncogene in 8 patients (7,4%). Carriers had mutation of exon 11, codon 634: TGC to CGC (5 patients), exon 11, codon 634: TGC to GGC (1 patient), exon 11, codon 634: TGC to TGG (1 patient) and in exon 13, codon 791: TAT to TTT (1 patient). Hyperactivity of thyroid C-cells was found in 5 carriers, borderline values of basal and after pentagastrin CT were found in 2 carriers and in only one patient CT concentration was normal. In four patients with RET proto-oncogene mutations, MTC was confirmed histopathologically in fine-needle biopsy. In three of them total thyroidectomy was performed. Two patients refused to be surgically treated (one with positive result of biopsy); the next three RET proto-oncogene germline mutation carriers have been informed that prophylactic total thyroidectomy should be considered. In none of the carriers hyperparathyroidism was observed. Conclusions Our study indicates that patients with pheochromocytoma should be genetically screened for mutations of the RET proto-oncogene. The carriers of these mutations should undergo thyroidectomy. In addition, genetic studies can be useful for the screening of the carriers families

Maternal and fetal outcomes in phaeochromocytoma and pregnancy:a multicentre retrospective cohort study and systematic review of literature

Background Phaeochromocytoma or paraganglioma (collectively known as PPGL) in pregnant women can lead to severe complications and death due to associated catecholamine excess. We aimed to identify factors associated with maternal and fetal outcomes in women with PPGL during pregnancy.Methods We did a multicentre, retrospective study of patients with PPGL and pregnancy between Jan 1, 1980, and Dec 31, 2019, in the International Pheochromocytoma and Pregnancy Registry and a systematic review of studies published between Jan 1, 2005, and Dec 27, 2019 reporting on at least five cases. The inclusion criteria were pregnancy after 1980 and PPGL before or during pregnancy or within 12 months post partum. Eligible patients from the retrospective study and systematic review were included in the analysis. Outcomes of interest were maternal or fetal death and maternal severe cardiovascular complications of catecholamine excess. Potential variables associated with these outcomes were evaluated by logistic regression.Findings The systematic review identified seven studies (reporting on 63 pregnancies in 55 patients) that met the eligibility criteria and were of adequate quality. A further 197 pregnancies in 186 patients were identified in the International Pheochromocytoma and Pregnancy Registry. After excluding 11 pregnancies due to potential overlap, the final cohort included 249 pregnancies in 232 patients with PPGL. The diagnosis of PPGL was made before pregnancy in 37 (15%) pregnancies, during pregnancy in 134 (54%), and after delivery in 78 (31%). Of 144 patients evaluated for genetic predisposition for phaeochromocytoma, 95 (66%) were positive. Unrecognised PPGL during pregnancy (odds ratio 27.0; 95% CI 3.5-3473.1), abdominal or pelvic tumour location (11.3; 1.5-1440.5), and catecholamine excess at least ten-times the upper limit of the normal range (4.7; 1.8-13.8) were associated with adverse outcomes. For patients diagnosed during pregnancy, alpha-adrenergic blockade therapy was associated with fewer adverse outcomes (3.6; 1.1-13.2 for no alpha-adrenergic blockade vs alpha-adrenergic blockade), whereas surgery during pregnancy was not associated with better outcomes (0.9; 0.3-3.9 for no surgery vs surgery).Interpretation Unrecognised and untreated PPGL was associated with a substantially higher risk of either maternal or fetal complications. Appropriate case detection and counselling for premenopausal women at risk for PPGL could prevent adverse pregnancy-related outcomes. Copyright (C) 2020 Elsevier Ltd. All rights reserved

Clinical Features of Paraganglioma Syndromes

Head and neck paragangliomas (HNPs) and pheochromocytomas are rare tumors. Sporadic and hereditary forms are recognized. Four different paraganglioma syndromes (PGLs 1–4) have been described: PGL 1 is associated with mutations of the succinate dehydrogenase (SDH) subunit D (SDHD) gene; PGL 3 is caused by SDHC gene mutations; PGL 4 is caused by SDHB gene mutations; the susceptibility gene for PGL 2 is unknown. The objective of this study is to review distinct clinical features of the different PGLs. An international registry for HNPs was founded in Freiburg, Germany, in 2000. The data presented in this article have been acquired from registered HNP patients who have been screened for mutations of the genes SDHB, SDHC, and SDHD. Approximately 30% of apparent sporadic HNPs are caused by a germline mutation in one of these genes. Patients with PGL 1 or 4 have a very high lifetime risk of developing HNPs as well as thoracic and abdominal pheochromocytomas. Compared with sporadic HNPs, tumors developing in SDHB, SDHC, and SDHD mutation carriers arise at a significantly younger age. The SDHB mutations are associated with a high percentage of malignant paraganglionic tumors. We recommend molecular genetic screening of all HNP patients for SDHB, SDHC, and SDHD gene mutations. Mutation carriers must be screened for paraganglial tumors in the head, neck, thorax, and abdomen. Appropriately timed surgical intervention will minimize disease-specific morbidity and mortality. Lifelong follow-up is mandatory

Juxtacondylar Approach in Temporal Paraganglioma Surgery: When and Why?

As it became clear that patients with paraganglioma (PGL) syndromes had a higher risk of multifocal tumors, we changed our surgical strategy to avoid the possibility of bilateral cranial nerve paralysis. The juxtacondylar approach offers advantages for some jugular foramen tumors, including types C and D temporal PGLs. This approach allows exposure of the jugular foramen without skeletonizing or transposing the facial nerve. It improves the surgeon's ability to distinguish between the pars vascularis and the pars nervosa at the jugular foramen, and it helps to save functioning of the lower cranial nerves. There is already considerable experience using the juxtacondylar approach for patients suffering from schwannomas and meningiomas involving the jugular foramen. Some limitations have been noted for using the juxtacondylar approach with jugular PGLs that are related to their vascular nature. In this article we demonstrate its use for the management of eight patients with locally advanced temporal PGLs and how it can be combined with an infratemporal fossa approach

Mutations in factor H reduce binding affinity to C3b and heparin and surface attachment to endothelial cells in hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) is a disease characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. Recent studies have identified a factor H–associated form of HUS, caused by gene mutations that cluster in the C-terminal region of the complement regulator factor H. Here we report how three mutations (E1172Stop, R1210C, and R1215G; each of the latter two identified in three independent cases from different, unrelated families) affect protein function. All three mutations cause reduced binding to the central complement component C3b/C3d to heparin, as well as to endothelial cells. These defective features of the mutant factor H proteins explain progression of endothelial cell and microvascular damage in factor H–associated genetic HUS and indicate a protective role of factor H for tissue integrity during thrombus formation

Hemangioblastoma and von Hippel-Lindau disease: genetic background, spectrum of disease, and neurosurgical treatment

Introduction!#!Hemangioblastomas are rare, histologically benign, highly vascularized tumors of the brain, the spinal cord, and the retina, occurring sporadically or associated with the autosomal dominant inherited von Hippel-Lindau (VHL) disease. Children or adults with VHL disease have one of > 300 known germline mutations of the VHL gene located on chromosome 3. They are prone to develop hemangioblastomas, extremely rarely starting at age 6, rarely at age 12-18, and, typically and almost all, as adults. There is a plethora of VHL-associated tumors and cysts, mainly in the kidney, pancreas, adrenals, reproductive organs, and central nervous system. Due to a lack of causal treatment, alleviation of symptoms and prevention of permanent neurological deficits as well as malignant transformation are the main task. Paucity of data and the nonlinear course of tumor progression make management of pediatric VHL patients with hemangioblastomas challenging.!##!Methods!#!The Freiburg surveillance protocol was developed by combining data from the literature and our experience of examinations of > 300 VHL patients per year at our university VHL center.!##!Results!#!Key recommendations are to start screening of patients at risk by funduscopy with dilated pupils for retinal tumors with admission to school and with MRI of the brain and spinal cord at age 14, then continue biannually until age 18, with emergency MRI in case of neurological symptoms. Indication for surgery remains personalized and should be approved by an experienced VHL board, but we regard neurological symptoms, rapid tumor growth, or critically large tumor/cyst sizes as the key indications to remove hemangioblastomas. Since repeated surgery on hemangioblastomas in VHL patients is not rare, modern neurosurgical techniques should encompass microsurgery, neuronavigation, intraoperative neuromonitoring, fluorescein dye-based intraoperative angiography, intraoperative ultrasound, and minimally invasive approaches, preceded in selected cases by endovascular embolization. Highly specialized neurosurgeons are able to achieve a very low risk of permanent morbidity for the removal of hemangioblastomas from the cerebellum and spinal cord. Small retinal tumors of the peripheral retina can be treated by laser coagulation, larger tumors by cryocoagulation or brachytherapy.!##!Conclusion!#!We consider management at experienced VHL centers mandatory and careful surveillance and monitoring of asymptomatic lesions are required to prevent unnecessary operations and minimize morbidity