Alopecia areata incognita (AAI) is a type of diffuse hair fall with no confirmatory diagnostic test. The UL16 binding protein-3 (ULBP3) is ligands for natural-killer group 2, member D (NKG2D) receptor. It is a key regulator of both innate and adaptive immune responses. In the normal hair follicle, ULBP3 is turned off. However, different studies reported its high level in alopecia areata (AA). Therefore, this study was done to evaluate ULBP3 in AAI in comparison with telogen effluvium (TE), female pattern hair loss (FPHL), and normal hair. Biopsy specimens from 36 females suffering from AAI, 15 with FPHL, nine with TE, and ten healthy female controls were subjected to the immunogenetic detection of ULBP3 levels by real-time polymerase chain reaction (PCR). A high statistically significant increase in ULBP3 level in AAI patient group compared with FPHL, TE, and normal hair was detected. ULBP3 levels were positively correlated with the age and duration of the disease. Accordingly, ULBP3 may act as a confirmatory test for AAI. ULBP3 may be implicated in the disease pathogenesis, progression, and chronicity, and AAI may be a subtype of AA.
Keywords: Alopecia areata; Alopecia areata incognita; Androgenetic alopecia; Dermoscopy; Telogen effluvium; ULBP3.