[Germline gene testing of the RET, VHL, SDHD and SDHB genes in patients with pheochromocytoma/paraganglioma].

OBJECTIVE

To analyze the germline variations of genes RET, VHL, SDHD and SDHB in patients with pheochromocytoma and/or paraganglioma and to evaluate variations of these genes in Chinese patients.

METHODS

Patients who were treated in Peking University First Hospital from September 2012 to March 2014 and diagnosed with pheochromocytoma and/or paraganglioma by pathologists were included in this study. Twelve patients were included in total, of whom 11 had pheochromocytoma, and 1 had paraganglioma. Deoxyribonucleic acid (DNA) was extracted from the leukocytes of peripheral blood of the patients. The exons 10, 11, 13-16 of the RET gene, and all exons of VHL, SDHB and SDHD genes and their nearby introns (±20 bp) were amplified with polymerase chain reactions, and the products were sent to a biotechnology company for sequencing. The sequencing results were compared with wildtype sequences of these genes to identify variations. One of the patients was diagnosed with multiple endocrine neoplasia type 2A. A family analysis was performed in his kindred, and his family members received genetic tests for the related variations.

RESULTS

Three patients were found to have germline gene variations. A c.136C>T (p.R46X) variation of the SDHB gene was found in a patient with malignant pheochromocytoma. A c.1901G>A (C634Y) variation, as well as c.2071G>A (p.G691S) and c.2712C>G (p.S904S) variations of the RET gene were found in a patient with multiple endocrine neoplasia type 2A. After a family analysis, five family members of this patient were found to have the same variations. c.2071G>A (p.G691S) and c.2712C>G (p.S904S) variations of the RET gene were also found in a clinical sporadic patient without evidence of malignancy. A patient with congenital single ventricle malformation and pheochromocytoma was included in this study, and no variation with clinical significance was found in the four genes of this patient.

CONCLUSION

25% (3/12) patients with pheochromocytoma or paraganglioma were found to have missense or nonsense germline gene variations in this study, including the c.136C>T (p.R46X) variation of the SDHB gene, the c.1901G>A (C634Y) variation of the RET gene, and c.2071G>A (p.G691S) and c.2712C>G (p.S904S) variations of the RET gene. The former two variations have already been confirmed to be pathogenic. The existence of these variations in Chinese patients with pheochromocytoma and/or paraganglioma was validated in this study, which supports the conclusion that genetic testing is necessary to be generally performed in patients with pheochromocytoma and/or paraganglioma.