Clinical presentations, biochemical phenotypes, and genotype-phenotype correlations in patients with succinate dehydrogenase subunit B-associated pheochromocytomas and paragangliomas

J Clin Endocrinol Metab. 2007 Mar;92(3):779-86. doi: 10.1210/jc.2006-2315. Epub 2007 Jan 2.


Context: Mutations of the gene encoding succinate dehydrogenase subunit B (SDHB) predispose to malignant paraganglioma (PGL). Recognition of the SDHB phenotype in apparently sporadic PGL directs appropriate treatment and family screening.

Objective: The objective of the study was to assess mutation-specific clinical and biochemical characteristics of SDHB-related PGL.

Design: The study design was retrospective descriptive.

Patients: PATIENTS included 29 patients (16 males) with SDHB-related abdominal or thoracic PGL.

Intervention: There was no intervention.

Main outcome measures: Clinical presentations, plasma and urine concentrations of catecholamines and O-methylated metabolites, and genotype-phenotype correlations were measured.

Results: Mean +/- sd age at diagnosis was 33.7 +/- 15.7 yr. Tumor-related pain was among the presenting symptoms in 54% of patients and was the sole symptom in 14%. Seventy-six percent had hypertension, and 90% lacked a family history of PGL. All primary tumors but one originated from extraadrenal locations. Mean +/- sd tumor size was 7.8 +/- 3.7 cm. In this referral-based study, 28% presented with metastatic disease and all but one eventually developed metastases after 2.7 +/- 4.1 yr. Ten percent had additional head and neck PGLs. The biochemical phenotype was consistent with hypersecretion of both norepinephrine and dopamine in 46%, norepinephrine only in 41%, and dopamine only in 3%. Ten percent had normal catecholamine (metabolite) levels, consistent with biochemically silent PGL. No obvious genotype-phenotype correlations were identified.

Conclusions: SDHB-related PGL often presents as apparently sporadic PGL with symptoms related to tumor mass effect rather than to catecholamine excess. The predominant biochemical phenotype consists of hypersecretion of norepinephrine and/or dopamine, whereas 10% of tumors are biochemically silent. The clinical expression of these tumors cannot be predicted by the genotype.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Adolescent
  • Adrenal Gland Neoplasms / genetics*
  • Adult
  • Aged
  • Child
  • Female
  • Genotype
  • Humans
  • Iron-Sulfur Proteins / genetics*
  • Male
  • Middle Aged
  • Paraganglioma / genetics*
  • Phenotype
  • Pheochromocytoma / genetics*
  • Retrospective Studies
  • Succinate Dehydrogenase / genetics*


  • Iron-Sulfur Proteins
  • SDHB protein, human
  • Succinate Dehydrogenase