Pachyonychia Congenita with a Novel Variant in the KRT16 Gene, c.348_379delinsAA.

Corresponding Author Je-Ho Mun Department of Dermatology, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul 03080, Korea Tel: +82-2-2072-3274, Fax: +82-2-742-7344, E-mail: jehomun@gmail.com https://orcid.org/0000-0002-0734-2850 *These authors have equally contributed to the article. Dear Editor: Pachyonychia congenita (PC) is a rare autosomal dominant keratinization disorder primarily affecting the skin and nails. PC is caused by dominant-negative mutations in one of five different keratin genes: KRT6A, KRT6B, KRT6C, KRT16, or KRT17. A Korean adolescent in his late 10s presented with painful plantar hyperkeratosis and nail changes. Due to plantar pain, he had difficulty in walking. His mother and sister had similar lesions. Physical examination revealed plantar keratoderma and dystrophic hyperkeratotic yellowish nails. Leukokeratosis of the oral mucosa was also observed (Fig. 1). A punch biopsy was obtained from his left sole (Fig. 2A). Microscopic examination of the sample showed marked acanthosis with hyperkeratosis, suggestive of palmoplantar keratoderma. We received the patient’s consent form about publishing all photographic materials. Blood sample was obtained to perform target gene sequencing using a next-generation sequencing panel. A novel likely pathogenic variant (PM1+PM2+PM4+PP1+PP3) in the KRT16 gene (NM_005557.3:c.348_379delinsAA) was