Table 2. Main syndromic features associated with specific hereditary PPGL.

Gene	Syndrome	Tumor location	Rate of PPGL metastases	Association with other tumors
NF1	Neurofibromatosis type 1	Mostly adrenal (bilateral)	12%	Neurofibromas, malignant tumors of the peripheral nerve sheath, optic gliomas and leukemias
RET	Multiple endocrine neoplasia type 2	Adrenal (bilateral)	<5%	Medullary thyroid carcinoma, parathyroid adenomas/ hyperplasia
VHL	von Hippel Lindau	Mostly adrenal (bilateral)	5-8 %	Renal clear cell (RCC) carcinoma, neuroendocrine tumors of the pancreas (mostly non-functioning), CNS hemangioblastomas, endolymphatic sac tumors, pituitary adenomas
SDHA	Hereditary PGL syndrome	Any	30-60%	RCC carcinoma, gastro-intestinal stromal tumors (GIST) and pituitary adenomas
SDHB	Hereditary PGL syndrome	Any, mostly extra-adrenal	35-75%	RCC carcinoma, GIST and pituitary adenomas
SDHC	Hereditary PGL syndrome	Head and neck, can be thoracic	Low	RCC carcinoma, GIST and pituitary adenomas
SDHD	Hereditary PGL syndrome	Any, mostly head and neck	15-29%	RCC carcinoma, GIST and pituitary adenomas
SDHAF 2 (SDH5)	Hereditary PGL syndrome	Head and neck (multifocal)	Not Known	RCC carcinoma, GIST and pituitary adenoma
TMEM 127	Familial PGL syndrome	Any, mostly adrenal	Low	RCC carcinoma
MAX	Familial PGL syndrome	Mostly adrenal (bilateral)	Intermediate to high	Pituitary adenomas
EPAS1	Familial PGL syndrome, polycythemia	Any	Unknown	Somatostatinoma
FH	Hereditary leiomatosis, RCC carcinoma	Any	Possibly high	Cutaneous and uterine leiomyomas, renal papillary carcinoma
MDH2		Any	Unknown