Published data show that these CE-marked IgM immunoblot assays (ViraMed, Euroimmun) demonstrate strong diagnostic accuracy, with reported sensitivities ranging from 90.0% to 94.4% and specificities between 97.1% and 99.2% when evaluated against composite or reference standards in infants and neonates with suspected CS (13–15,16,19,20). The gene discussed is CD40LG; the disease is Cowden syndrome 1.