In the current study, individuals with skin manifestation showed significant lower level of YKL-40, this is not in agreement with a previous Japanese study that stated elevated levels of YKL-40 in Japanese patients with psoriasis and suggested that YKL-40 serum levels can act as a valuable biomarker for detecting the severity of dermatological lesions in psoriasis patients [41]. This evidence concerns the gene CHI3L1 and psoriasis.