This thesis aims to gain insight in the genetics, inheritance and tumor biology of head and neck paragangliomas, with a focus on SDHD and SDHAF2-related tumors. Mutations in SDHD and SDHAF2... Show moreThis thesis aims to gain insight in the genetics, inheritance and tumor biology of head and neck paragangliomas, with a focus on SDHD and SDHAF2-related tumors. Mutations in SDHD and SDHAF2 show a remarkable parent-of-origin dependent tumorigenesis in which tumor formation almost exclusively occurs following paternal transmission of the mutation. The Hensen model is discussed to explain this striking inheritance pattern seen in SDHD and SDHAF2-linked families. Show less
Genetically defined mitochondrial deficiencies that result in the loss of complex II function lead to a range of clinical conditions. An array of tumor syndromes caused by complex II-associated... Show moreGenetically defined mitochondrial deficiencies that result in the loss of complex II function lead to a range of clinical conditions. An array of tumor syndromes caused by complex II-associated gene mutations, in both succinate dehydrogenase and associated accessory factor genes (SDHA, SDHB, SDHC, SDHD, SDHAF1, SDHAF2), have been identified over the last 12 years and include hereditary paraganglioma-pheochromocytomas, a diverse group of renal cell carcinomas, and a specific subtype of gastrointestinal stromal tumors (GIST). In addition, congenital complex II deficiencies due to inherited homozygous mutations of the catalytic components of complex II (SDHA and SDHB) and the SDHAF1 assembly factor lead to childhood disease including Leigh syndrome, cardiomyopathy and infantile leukodystrophies. The role of complex II subunit gene mutations in tumorigenesis has been the subject of intensive research and these data have led to a variety of compelling hypotheses. Among the most widely researched are the stabilization of hypoxia inducible factor 1 under normoxia, and the generation of reactive oxygen species due to defective succinate:ubiquinone oxidoreductase function. Further progress in understanding the role of complex II in disease, and in the development of new therapeutic approaches, is now being hampered by the lack of relevant cell and animal models. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease. Show less
