Recurrent fungal infections Unusual fungal nail infection Recurrent onychomycosis Chronic nail candidiasis Recurrent fungal nail infection Chronic onychomycosis Increased susceptibility to recurrent fungal nail infection (onychomycosis), as manifested by recurrent or persistent infection of the nail plate, nail bed, or nail matrix caused by dermatophytes (Trichophyton species) or Candida species. Recurrent onychomycosis is a characteristic feature of chronic mucocutaneous candidiasis (CMC) due to STAT1 gain-of-function, STAT3 loss-of-function, or other IL-17 pathway defects.