In the outbreak of hand, foot, and mouth disease (HFMD) which occurred in Finland in 2008, in which onychomadesis was a common symptom, Osterback et al. detected CA6 in shed nail fragments of a patient who had onychomadesis following a HFMD episode by using RT-PCR and suggested that CA6 virus replication damaged the nail matrix, resulting in onychomadesis [8]. The gene discussed is CA6; the disease is hand, foot and mouth disease.