A literature search showed no reports of nail deformities due to pernio. Here, we present a pernio case who developed nail deformities after extended exposure to cold, if combined with other facilitating factors. [jpma.org.pk]

A pincer nail deformity is inherited or acquired and can be associated with beta-blocker use, psoriasis, onychomycosis, tumors of the nail apparatus, systemic lupus erythematosus, Kawasaki disease, and malignancy. [aafp.org]

In adults the most common systemic association is with iron deficiency and haemochromatosis, although the majority of adults with koilonychia demonstrate a familial pattern Pincer nail deformity - is a transverse over-curvature of the nail plate. [pcds.org.uk]

They did not report any abnormal or delayed dentition, abnormal sweating or anhidrosis, musculoskeletal, ocular, or neurologic symptoms. Their mother reported with the history of dystrophic nails since birth. [ijtrichology.com]

Que SK, Sloan B, Dadras SS: Trachyonychia, cutis laxa, and easy bruising of the skin. Amyloidosis. JAMA Dermatol 2014;150:1357-1358. [karger.com]