Hereditary paraganglioma-pheochromocytoma (PGL/PCC) syndromes are characterized by paragangliomas and pheochromocytomas and have been associated with germline heterozygous mutations in MAX, SDHA, SDHAF2, SDHB, SDHC, SDHD, or TMEM127.
Pathogenic germline SDHA variants were identified in 30 of the 393 referred patients with PGL (7.6%), who had head and neck PGL (21 of 174 [12%]), pheochromocytoma (4 of 191 [2%]), or sympathetic PGL (5 of 28 [18%]).
Thirty per cent are associated with SDHA germline mutation and 50% are associated with SDHC epimutation (post-zygotic promoter hypermethylation) - the hallmark of the syndromic but non-hereditary Carney triad (SDH- deficient GIST, SDH-deficient paraganglioma and pulmonary chondroma).
Of 972 unrelated registrants without mutations in the classic pheochromocytoma- and paraganglioma-associated genes (632 female [65.0%] and 340 male [35.0%]; age range, 8-80; mean [SD] age, 41.0 [13.3] years), 58 (6.0%) carried germline mutations of interest, including 29 SDHA, 20 TMEM127, 8 MAX, and 1 SDHAF2.
We investigated whether SDHA/SDHB immunohistochemistry is able to identify SDH-related tumours in a retrospective case series of phaeochromocytomas (PCCs) and paragangliomas (PGLs).
SDHB/SDHA immunohistochemistry in pheochromocytomas and paragangliomas: a multicenter interobserver variation analysis using virtual microscopy: a Multinational Study of the European Network for the Study of Adrenal Tumors (ENS@T).
Although 14 different genes have been linked to paraganglioma/pheochromocytoma, a subgroup of these genes is associated with hereditary paraganglioma-pheochromocytoma, the genes related to mitochondrial succinate dehydrogenase (SDH) including SDHA, SDHB, SDHC, SDHD and the assembly factor SDHAF2.
We hypothesised that PC/PGLs containing SDHx or VHL mutations, and succinate dehydrogenase (SDH)-deficient gastrointestinal stromal tumours (GISTs), would overexpress miR-210 relative to non-SDH or -VHL-mutated counterparts. miR-210 was analysed by quantitative PCR in i) 39 PC/PGLs, according to genotype (one SDHA, five SDHB, seven VHL, three NF1, seven RET, 15 sporadic, one unknown) and pathology (18 benign, eight atypical, 11 malignant, two unknown); ii) 18 GISTs, according to SDHB immunoreactivity (nine SDH-deficient and nine SDH-proficient) and iii) two novel SDHB-mutant neurosphere cell lines. miR-210 was higher in SDHx- or VHL-mutated PC/PGLs (7.6-fold) compared with tumours without SDHx or VHL mutations (P=0.0016). miR-210 was higher in malignant than in unequivocally benign PC/PGLs (P=0.05), but significance was lost when benign and atypical tumours were combined (P=0.08).
About 60% of Pheochromocytoma (PCC) and Paraganglioma (PGL) patients have either germline or somatic mutations in one of the 12 proposed disease causing genes; SDHA, SDHB, SDHC, SDHD, SDHAF2, VHL, EPAS1, RET, NF1, TMEM127, MAX and H-RAS.
Mutations in genes (SDHB, SDHD, SDHC, and SDHA) encoding a component of the tricarboxylic acid cycle, succinate dehydrogenase (SDH), are a major cause of inherited PCC and PGL.
The loss of SDHA protein expression in both the paraganglioma (proband) and pituitary adenoma (proband's son) argues strongly for a causative role of SDHA mutation.
Heterozygous germline mutations in SDHA, SDHB, SDHC, SDHD and in the assembly factor encoding gene SDHAF2 have all been shown to predispose to heritable endocrine neoplasias such as pheochromocytomas (PHEO) and paragangliomas (PGLs) called 'PHEO-PGL syndrome'.
SDHA and SDHB immunohistochemistry are reliable techniques to identify pheochromocytomas and paragangliomas with mutations in SDHA, SDHB, SDHC and SDHD.
Pheochromocytomas and paragangliomas are neuroendocrine tumors that occur in the context of inherited cancer syndromes in ∼30% of cases and are linked to germline mutations in the VHL, RET, NF1, SDHA, SDHB, SDHC, SDHD, SDHAF2 and TMEM127 genes.
The SDHAF2 gene encodes an SDH co-factor related to the function of the SDHA subunit, and is currently exclusively associated with head and neck paragangliomas.
Here we introduce all reported paraganglioma and pheochromocytoma related sequence variations in these genes, in addition to all reported mutations of SDHA.The database is now accessible online.