[Pheochromocytoma - still a challenge]

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Zusammenfassung. In diesem Mini-Review wird aufgezeigt, dass die Diagnostik der sekundären Hypertonie eigentlich eine relativ einfache Unternehmung ist. Neben einer umfassenden Anamnese sowie einer korrekt durchgeführten klinischen Untersuchung muss bei jeder Diagnosestellung einer arteriellen Hypertonie an die Möglichkeit einer sekundären Ursache gedacht werden. Oft ist es auch kostengünstiger, beim geringsten Verdacht direkt nach einer sekundären Ursache zu suchen, als durch langwierige Umstellungen der Therapie und damit auch Verunsicherung des Patienten die Diagnostik zu verzögern.

Clinical predictors and algorithm for the genetic diagnosis of pheochromocytoma patients

PURPOSE

Six pheochromocytoma susceptibility genes causing distinct syndromes have been identified; approximately one of three of all pheochromocytoma patients carry a predisposing germline mutation. When four major genes (VHL, RET, SDHB, SDHD) are analyzed in a clinical laboratory, costs are approximately $3,400 per patient. The aim of the study is to systematically obtain a robust algorithm to identify who should be genetically tested, and to determine the order in which genes should be tested.

EXPERIMENTAL DESIGN

DNA from 989 apparently nonsyndromic patients were scanned for germline mutations in the genes VHL, RET, SDHB, SDHC, and SDHD. Clinical parameters were analyzed as potential predictors for finding mutations by multiple logistic regression, validated by bootstrapping. Cost reduction was calculated between prioritized gene testing compared with that for all genes.

RESULTS

Of 989 apparently nonsyndromic pheochromocytoma cases, 187 (19%) harbored germline mutations. Predictors for presence of mutation are age <45 years, multiple pheochromocytoma, extra-adrenal location, and previous head and neck paraganglioma. If we used the presence of any one predictor as indicative of proceeding with gene testing, then 342 (34.6%) patients would be excluded, and only 8 carriers (4.3%) would be missed. We were also able to statistically model the priority of genes to be tested given certain clinical features. E.g., for patients with prior head and neck paraganglioma, the priority would be SDHD>SDHB>RET>VHL. Using the clinical predictor algorithm to prioritize gene testing and order, a 44.7% cost reduction in diagnostic process can be achieved.

CONCLUSIONS

Clinical parameters can predict for mutation carriers and help prioritize gene testing to reduce costs in nonsyndromic pheochromocytoma presentations.