With great interest we read the editorial “Fabry Disease: More Than Angiokeratomas” by Möhrenschlager and colleagues.1 We concur with the authors that it would be appealing to use angiokeratoma as a disease marker, as a quasi–“window into the body”; however, the use of surrogate markers has produced a lot of controversy. According to the principles summarized by Prentice,2 to evaluate the suitability of angiokeratomas as an appropriate surrogate marker, it has to be shown that this variable correlates highly with the true clinical outcome, which is primarily end-organ involvement at a given moment. In addition, as longitudinal surrogate markers, angiokeratomas require capturing the net effect of the treatment (ie, risk reduction for the development of stroke or kidney failure in patients with Fabry disease).
Ries M, Schiffmann R. Fabry Disease: Angiokeratoma, Biomarker, and the Effect of Enzyme Replacement Therapy on Kidney Function. Arch Dermatol. 2005;141(7):904-906. doi:10.1001/archderm.141.7.904-b