Sentence:  Dyskeratosis congenita is a rare congenital syndrome, characterized by the triad of reticular skin pigmentation, mucosal leukoplakia, and nail dystrophy, plus the predisposition to bone marrow failure and malignancy. ... Other cutaneous findings may include alopecia, hyperkeratosis of the palms and soles, and <WSD>adermatoglyphia</WSD> (loss of dermal ridges on fingers and toes). 
Meaning of the word marked with <WSD> tags:  The rare congenital absence of epidermal ridges (fingerprints and toeprints).