Publications by authors named "Kristin Aaberg"

3 Publications

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APC mosaicism in a young woman with desmoid type fibromatosis and familial adenomatous polyposis.

Fam Cancer 2018 10;17(4):539-543

Section of Inherited Cancer, Department of Medical Genetics, Oslo University Hospital, Oslo, Norway.

Familial adenomatous polyposis (FAP) is usually caused by germline mutations in the adenomatous polyposis coli (APC) gene. The classic form is characterized by hundreds to thousands of adenomas in the colorectum and early onset colorectal cancer (CRC) if left untreated. FAP is also associated with multiple extra-colonic manifestations such as gastroduodenal polyps, osteomas, epidermoid cysts, fibromas and desmoids. Most desmoid tumours in FAP patients occur intra-abdominally. Approximately 15-20% of the APC mutations are de novo mutations. Somatic mosaicism has been reported in some sporadic cases of polyposis but is probably an underestimated cause of the disease. This case report presents the detection of a mosaic APC mutation in a 26-year-old woman who as a child had been diagnosed with desmoid type fibromatosis. FAP was suggested when she presented with extensive extra abdominal fibromatosis. Our findings indicate that APC mutations may be suspected in patients presenting with a desmoid regardless of its location. If there is clinical evidence that the patient has FAP, adenomas and colonic mucosa in addition to leukocyte DNA should be included in the screening, preferably using methods that are more sensitive than Sanger sequencing.
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October 2018

Do Not Be Fooled by Fancy Mutations: Inflammatory Fibroid Polyps Can Harbor Mutations Similar to Those Found in GIST.

Case Rep Med 2013 6;2013:845801. Epub 2013 Nov 6.

Department of Pathology, Oslo University Hospital, Norwegian Radium Hospital, Pb 4953 Nydalen, 0424 Oslo, Norway.

Goal. Surgeons that remove a typical polyp from the stomach or small intestine should be reluctant to accept a diagnosis of GIST just because there is a mutation in platelet-derived growth factor receptor alfa (PDGFRA). Background. A subtype of gastric and intestinal polyps is denoted as inflammatory fibroid polyp (IFP). In some of these cases a mutation in PDGFRA is found, leading to the diagnosis of gastrointestinal stromal tumor (GIST). Study. This study includes two patients that had polyps removed from the ileum, and an extended investigation was performed with immunohistochemical staining and mutation analyses. Results. The tumors did not show typical immunohistochemical staining for markers used to diagnose GIST, but the mutation analysis revealed a mutation in PDGFRA exon 12. On the basis of the mutation analysis, both polyps were primarily diagnosed as GISTs, but the diagnosis was later changed to inflammatory fibroid polyp. Conclusion. It is important that both surgeons and pathologists be aware that IFP can harbor a mutation in PDGFRA where further treatment and follow-up is different with the two different diagnoses. A mutation analysis can be misleading when taken out of the context of clinical observations, histological characteristics and immunohistochemical staining.
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December 2013

APC mutation spectrum of Norwegian familial adenomatous polyposis families: high ratio of novel mutations.

J Cancer Res Clin Oncol 2009 Oct 15;135(10):1463-70. Epub 2009 May 15.

Pathology Division, University Hospital of Oslo-Rikshospitalet, N0027 Oslo, Norway.

Introduction: Familial adenomatous polyposis (FAP) is an autosomal dominantly inherited disease caused by mutations in the adenomatous polyposis coli (APC) gene. Massive formation of colorectal adenomas, of which some will inevitably develop into adenocarcinomas, is the hallmark of the disease. Characterization of causative APC mutations allows presymptomatic diagnosis, close follow-up and prophylactic intervention in families. To date more than 900 different germline mutations have been characterized worldwide demonstrating allelic heterogeneity.

Purpose: The germline mutation spectrum of APC identified in 69 apparently unrelated Norwegian FAP families are presented and discussed with reference to clinical phenotype and novel mutation rate.

Methods: Different methods have been used over the years. However, all mutations were confirmed detectable by an implemented denaturing high-performance liquid chromatography screening approach. Multiplex ligation-dependent probe amplification analysis was employed for potential gross rearrangements.

Results: Fifty-three distinctive mutations were detected, of which 22 have been detected in Norway exclusively. Except for two major deletion mutations encompassing the entire APC, all mutations resulted in premature truncation of translation caused by non-sense (31%) or change in reading frame (69%).

Conclusion: A high ratio of novel APC mutations continues to contribute to APC mutation heterogeneity causing FAP. This is the first comprehensive report of APC germline mutation spectrum in Norway.
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October 2009