SDHD and pachyonychia congenita: RAPTAS may be caused by germline mutations in six genes (VHL, SDHB, SDHC, SDHD, TMEM127, and MAX) and two further genes, FH and SDHA, have each been reported to predispose to both groups of tumors (PC/PGL/HNPGL and renal tumors) and may yet be described as a cause of RAPTAS.