SDH genetic testing, including tests for large genomic deletions, is indicated in all patients with head and neck and/or thoracic-abdominal or pelvic paraganglioma and can be targeted according to clinical criteria.
SDH status should be considered for all patients with paraganglioma as it may be important for patients' lifelong follow-up as well as for familial considerations.
An intriguing hypothesis proposes that mutations of RET, NF1, VHL, or SDH predispose to hereditary pheochromocytoma/ paraganglioma by causing defective apoptotic culling of cells that would normally be destroyed during embryogenesis.
Analysis of the SDH genes was performed in 29 patients and one kindred with familial PGL to identify germline mutations in the SDHB, SDHC, and SDHD genes by direct DNA sequencing.
Approximately 10% to 15% of paragangliomas are caused by mutations in the succinate dehydrogenase (SDH) genes B, C, or D. These are often multifocal as part of paraganglioma syndromes and hormone secreting, and malignant particularly associated with mutations in SDHB.
As SDH mutations are virtually always germline, we conclude that approximately 15% of all pheochromocytomas or paragangliomas are associated with germline SDH mutation and that immunohistochemistry can be used to triage genetic testing.
Forty percent of paragangliomas are linked to genetic syndromes, most commonly due to mutations of the succinate dehydrogenase (SDH) enzyme complex and are collectively known as paraganglioma syndromes, of which five are described.
Germ line heterozygous mutations in the structural subunit genes of mitochondrial complex II (succinate dehydrogenase; SDH) and the regulatory gene SDHAF2 predispose to paraganglioma tumors which show constitutive activation of hypoxia inducible pathways.
Germline mutations in SDH genes are responsible for 6% and 9% of sporadic paragangliomas and phaeochromocytomas, respectively, 29% of paediatric cases, 38% of malignant tumours and more than 80% of familial aggregations of paraganglioma and phaeochromocytoma.
Germline mutations in FH predispose individuals to leiomyomas and renal cell cancer (HLRCC), whereas mutations in SDH cause paragangliomas and phaeochromocytomas (HPGL).
Germline mutations in succinate dehydrogenase (SDH) genes predispose carriers for developing paragangliomas, and studies on their quality of life (QoL) are scarce.
IDH1 and IDH2 mutations are found in many neoplasms, and germline alterations in SDH genes and FH predispose to pheochromocytoma/paraganglioma and other cancers.
In order to characterize phenotypic effects of these mutations, the present study investigated the immunohistochemical expression of the catalytic subunits of complex II (flavoprotein and iron protein), SDH enzyme activity, and mitochondrial morphology in a series of 22 head and neck paragangliomas.