De Novo Mutation in KRT1 Leads to Epidermolytic Palmoplantar Keratoderma: from Chinese Traditional Treatment to Prenatal Diagnosis Using Whole-Exome Sequencing-Plus.

Congenital skin disorders are a class of complex genetic diseases that are difficult to diagnose and treat. We developed trio whole-exome sequencing-plus (WES-plus) for detecting de novo mutations and evaluated the use of traditional Chinese medicine (TCM) for treating congenital skin disorders. In this study, we successively performed panel-based next-generation sequencing (NGS) and Trio WES-plus in a child with frequent large blisters. Panel-based NGS revealed no pathogenic mutations. Trio WES-plus for resequencing based on cutaneous keratosis of the palms and feet detected a missense mutation (c.1436T>A, p.Ile479Asn) in the coding region of KRT1 in the child but not in his parents. Following prenatal diagnosis, a healthy second baby without the mutation was born. The disease symptoms of epidermolytic palmoplantar keratoderma (EPPK) application were improved by TCM and Western medicine. Our study revealed the pathogenicity of a de novo mutation in human KRT1, which expands the mutation spectrum of EPPK. Trio WES-plus is useful for diagnosing genetic diseases and providing genetic guidance from prenatal diagnosis to treatment.

Diagnosis and Management of Inherited Palmoplantar Keratodermas.

Inherited monogenic palmoplantar keratodermas are a heterogeneous group of conditions characterised by persistent epidermal thickening of the palmoplantar skin. Palmoplantar keratodermas are grouped depending on the morphology of the keratoderma into diffuse, focal/striate or papular/punctate. Some palmoplantar keratodermas just affect the skin of the palms and soles and others have associated syndromic features which include changes in hair, teeth, nails, hearing loss or cardiomyopathy. Next generation sequencing has helped discover genes involved in many of these conditions and has led to reclassification of some palmoplantar keratodermas. In this review, we discuss the diagnostic features of palmoplantar keratodermas and management options.

A STAT1-gain-of-function mutation causing Th17 deficiency with chronic mucocutaneous candidiasis, psoriasiform hyperkeratosis and dermatophytosis.

During recent years, inborn errors of human IL-17 immunity have been demonstrated to underlie primary immunodeficiencies with chronic mucocutaneous candidiasis (CMC). Various defects in receptors responsible for sensing of Candida albicans or downstream signalling to IL-17 may lead to susceptibility to Candida infection. While CMC is common in patients with profound T cell immunodeficiencies, CMC is also recognised as part of other immunodeficiencies in syndromic CMC, or as relatively isolated CMC disease. We describe a 40-year-old woman with a clinical picture involving cutaneous bacterial abscesses, chronic oral candidiasis and extensive dermatophytic infection of the feet. By whole exome sequencing, we identified a STAT1-gain-of-function mutation. Moreover, the patient's peripheral blood mononuclear cells displayed severely impaired Th17 responses. The patient was treated with antifungals and prophylactic antibiotics, which led to resolution of the infection. We discuss the current knowledge within the field of Th17 deficiency and the pathogenesis and treatment of CMC.

Possible anticipation in familial epidermolytic palmoplantar keratoderma with the p.R163W mutation of Keratin 9.

Epidermolytic palmoplantar keratoderma (EPPK) is an autosomal dominant disease characterized by diffuse hyperkeratosis of the epidermis of the palm and sole with an erythematous margin. The Keratin 9 (KRT9) and Keratin 1 genes are responsible for EPPK. Several previous studies have focused on the genetic basis of EPPK; however, genetic anticipation has not yet been reported. We described a four-generation family with EPPK and identified a p.R163W mutation of KRT9. We observed a decrease in the age of onset in three consecutive generations in the family of the proband, indicating possible genetic anticipation in this familial EPPK. Further studies are needed to elucidate the mechanisms of anticipation in EPPK.

KRT9 gene mutation as a reliable indicator in the prenatal molecular diagnosis of epidermolytic palmoplantar keratoderma.

Epidermolytic palmoplantar keratoderma (EPPK) is the most frequent form of such keratodermas. It is inherited in an autosomal dominant pattern and is clinically characterized by diffuse yellowish thickening of the skin on the palms and soles with erythematous borders during the first weeks or months after birth. EPPK is generally caused by mutations of the KRT9 gene. More than 26 KRT9 gene mutations responsible for EPPK have been described (Human Intermediate Filament Database, www.interfil.org), and many of these variants are located within the highly-conserved coil 1A region of the α-helical rod domain of keratin 9. Unfortunately, there is no satisfactory treatment for EPPK. Thus, prenatal molecular diagnosis or pre-pregnancy diagnosis is crucial and benefits those affected who seek healthy descendants. In the present study, we performed amniotic fluid-DNA-based prenatal testing for three at-risk pregnant EPPK women from three unrelated southern Chinese families who carried the KRT9 missense mutations p.Arg163Trp and p.Arg163Gln, and successfully helped two families to bear normal daughters. We suggest that before the successful application of preimplantation genetic diagnosis (PGD), and noninvasive prenatal diagnosis of EPPK that analyzes fetal cells or cell-free DNA in maternal blood, prenatal genetic diagnosis by amniocentesis or chorionic villus sampling (CVS) offers a quite acceptable option for EPPK couples-at-risk to avoid the birth of affected offspring, especially in low- and middle-income countries.

[Mutation analysis and prenatal diagnosis of keratin 9 gene in a large Chinese family with epidermolytic palmoplantar keratoderma].

OBJECTIVE: To analyze potential mutation in keration 9 (KRT9) gene in a large Chinese family with epidermolytic palmoplantar keratoderma (EPPK) and to perform prenatal diagnosis on the fetus at 10th gestational week. METHODS: Peripheral venous blood samples were obtained from 5 affected and 8 unaffected individuals of the family. Fifty unrelated healthy individuals were also recruited as controls. PCR was used to amplify exons 1 and 6 of KRT9 gene, and the products were sequenced directly. After the mutation was confirmed, prenatal diagnosis was performed on the fetus during the first trimester of pregnancy. RESULTS: A heterozygous missense mutation c.482A to G in the KRT9 gene, which has led to substitution of Asparaginate by Serine at codon 161 (p.N161S), was detected in all patients but not in other individuals of the family and the 50 healthy controls. The fetus was found to have carried the p.N161S mutation too. Following selected abortion, analysis of fetal tissue was consistent with prenatal diagnosis. CONCLUSION: The missense mutation c.482A to G (p.N161S), which has been shown previously to cause EPPK, is found in the KRT9 gene of patients in this family. Gene mutation analysis for prenatal diagnosis is efficient to facilitate detection of affected fetus in time.

The most common mutation of KRT9, c.C487T (p.R163W), in epidermolytic palmoplantar keratoderma in two large Chinese pedigrees.

Epidermolytic palmoplantar keratoderma (EPPK) is generally associated with dominant-negative mutations of the Keratin 9 gene (KRT9), and rarely with the Keratin 1 gene (KRT1). To date, a myriad of mutations has been reported with a high frequency of codon 163 mutations within the first exon of KRT9 in different populations. Notably, a distinct phenotypic heterogeneity, digital mutilation, was found recently in a 58-year-old female Japanese EPPK patient with p.R163W. Here, we report the most common mutation, c.C487T (p.R163W) of KRT9, in two large EPPK pedigrees from southeast China. The arginine residue in peptide position 163 remains almost constant in at least 47 intermediate filament proteins ranging from snail to human. A substitution in arginine alters both the charge and shape of the 1A rod domain and disrupts the function of the helix initiation motif of keratins, finally compromising the integrity of filaments and weakening their stability in the epidermis of palms and soles. We summarize the clinical symptoms of EPPK in Chinese and show that knuckle pads are associated with KRT9 mutations. We suggest that the frequency of p.R163W in Chinese EPPK patients (31.03%) is consistent with that in the general population (29.33%), and that codon 163 is truly a hotspot mutational site of KRT9.