Mutation p.Leu128Pro in the 1A domain of K16 causes pachyonychia congenita with focal palmoplantar keratoderma in a Chinese family

Mutation p.Arg127Pro in the 1A Domain of KRT16 Causes Pachyonychia Congenita in Chinese Patient: A Case Report of PC Associated with Acral Melanoma

Pachyonychia congenita (PC) is a group of rare hereditary disorders, characterised by hypertrophic nails and palmoplantar keratoderma (PPK), particularly localised to the pressure areas of the feet. At a molecular level, it is caused by mutations in genes encoding KRT6A, KRT6B, KRT6C, KRT16, or KRT17. To identify the underlying gene mutation in a Chinese family with PC presenting with disabling palmoplantar keratoderma and subsequent associated acral melanoma. Genomic DNA was extracted from peripheral blood samples of three available individuals in the Chinese family, which included the patient and his two unaffected sisters. The index patient presented with severe palmoplantar keratoderma as well as a newly diagnosed acral malignant melanoma (MM). Whole-exome sequencing (WES) was carried out with amplification of exon 1 of KRT16 by polymerase chain reaction (PCR). PCR products were then sequenced to identify potential mutations. We identified the proline substitution mutation p.Arg127Pro (c.380G>C) in our patient's 1A domain of KRT16. The same mutation was not found in his sisters or unrelated healthy controls. The mutation (p.Arg127Pro (c.380G>C)) in KRT16 has been reported in Dutch patients with PC. However, it is the first such report of a patient with a PC of Chinese origin. In addition, the acral MM occurred under the background of genetic PPK caused by KRT16 mutation in this patient.

Mutational analysis of epidermal and hyperproliferative type I keratins in mild and moderate psoriasis vulgaris patients: a possible role in the pathogenesis of psoriasis along with disease severity

Background

Mutations in keratin proteins have been vastly associated with a wide array of genodermatoses; however, mutations of keratins in psoriasis have not been fully investigated. The main aim of the current research was to identify the mutation in K14, K10, K16, and K17 genes in two stages of psoriasis patients.

Methods

Ninety-six psoriatic skin biopsies were collected. mRNA transcript of K14, K10, K16, and K17 was prepared, amplified, and sequenced. Sanger sequences of all keratins were further validated for mutational analysis using Mutation Surveyor and Alamut Visual. Then, in silico analysis of protein stability and protein and gene expression of all keratins was performed and validated.

Results

Out of 44 mutations, about 75% of keratins are highly pathogenic and deleterious. Remaining 25% mutations are less pathogenic and tolerated in nature. In these 33 deleterious mutations were immensely found to decrease keratin protein stability. We also found a correlation between keratin and Psoriasis Area and Severity Index score which added that alteration in keratin gene in skin causes severity of psoriasis.

Conclusions

We strongly concluded that acanthosis and abnormal terminal differentiation was mainly due to the mutation in epidermal keratins. In turn, disease severity and relapsing of psoriasis are mainly due to the mutation of hyperproliferative keratins. These novel keratin mutations in psoriatic epidermis might be one of the causative factors for psoriasis.

Electronic supplementary material

The online version of this article (10.1186/s40246-018-0158-2) contains supplementary material, which is available to authorized users.