Identification of novel homozygous SLURP1 mutation in a Javanese family with Mal de Meleda.

BACKGROUND: Mal de Meleda (OMIM# 248300; keratosis palmoplantaris transgrediens) is an autosomal recessive form of palmoplantar keratoderma, clinically characterized by sharp demarcated erythema and hyperkeratosis of the palms and soles that progress with age and extend to the dorsal aspects of the hands and feet. The mal de Meleda is caused by mutations in the SLURP1 gene that encodes secreted lymphocyte antigen 6/urokinase-type plasminogen receptor-related protein 1 (SLURP1). To date no reported cases from Indonesia. The aims of the study were to describe the typical features of mal de Meleda cases in a Javanese family in Indonesia and identify the mutation in the ARS B gene which encodes SLURP1. PATIENTS AND METHODS: In this study, three Javanese patients, siblings from nonconsanguineous nonaffected parents, presented with classical symptoms of mal de Meleda. Genetic analysis screening SLURP1 gene was conducted for the specimens from the patients and other family members. RESULTS: A novel homozygous three-nucleotide deletion in exon 3, i.e. c.271-273TCTdel, was identified in the patients. Subcloning and sequencing revealed both parents (I.2 and I.3) and one of the father's siblings (I.1) carry heterozygous c.271-273TCTdel, while the other father's sibling (I.2), the mother's sister (I.4), and a healthy control matched the ethnicity of the family, showing normal sequence of the entire SLURP1. CONCLUSION: This is the first mal de Meleda case of Javanese ethnicity to be documented, and the unique mutation has not previously been reported. The finding supports the notion that despite the rarity, SLURP1 mutation causing mal de Meleda is ubiquitous.

A novel mutation in TRPV3 gene causes atypical familial Olmsted syndrome.

Olmsted syndrome (OS) is a rare keratinization disorder, typically characterized by two primary diagnostic hallmarks--mutilating palmoplanter and periorificial keratoderma. However, there's a growing body of literature reporting on the phenotypic diversity of OS, including the absence of aforementioned hallmarks and the presence of some unusual clinical features. Here we presented an atypical familial case of OS that could be confused with Huriez syndrome due to the presence of a scleodactyly-like appearance and tapered fingers in the proband. We ruled out this possibility and made a definitive diagnosis of OS based on clinical features and a genetic assay. Recently, mutations in TRPV3 associated with autosomal dominant or recessive OS continued to be reported, thus conducing to clarifying the underlying relationship between the genotype and phenotype of OS. So we further explored the genotype-phenotype correlation by integrating functionl assays with in silico predictions. Our research not only redefined the phenotypic spectrum of OS, but also provided concrete molecular insights into how mutations in a single gene can lead to significant differences in the severity of this rare disease.

Mutations in the desmoglein 1 gene in five Pakistani families with striate palmoplantar keratoderma.

BACKGROUND: Striate palmoplantar keratoderma (SPPK; OMIM #148700) is a rare autosomal dominant genodermatosis characterized by linear hyperkeratosis on the digits and hyperkeratosis on the palms and soles. SPPK is known to be caused by heterozygous mutations in either the desmoglein 1 (DSG1), desmoplakin (DSP), or keratin 1 (KRT1) genes. OBJECTIVE: To define the molecular basis of SPPK in five Pakistani families showing a clear autosomal dominant inheritance pattern of SPPK. METHODS: Based on previous reports of DSG1 mutations in SPPK, we performed direct sequencing of the DSG1 gene of all five families. RESULTS: Mutation analysis resulted in the identification of one recurrent mutation (p.R26X) and four novel mutations (c.Ivs4-2A>G, c.515C>T, c.Ivs9-3C>G, and c.1399delA) in the DSG1 gene. Each mutation is predicted to cause haploinsufficiency of DSG1 protein. CONCLUSION: The results of our study further underscore the significance of the desmoglein gene family in diseases of epidermal integrity.

Papillon-Lefèvre syndrome and malignant melanoma. A high incidence of melanoma development in Japanese palmoplantar keratoderma patients.

Papillon-Lefèvre syndrome (PLS) is a rare autosomal-recessive genodermatosis characterized by palmoplantar hyperkeratosis and severe early-onset periodontitis. The development of malignant cutaneous neoplasms within the hyperkeratotic lesions of the syndrome is quite rare. Here, we report on a 51-year-old Japanese woman with PLS associated with recurrent malignant melanoma (MM). Mutation analysis of the cathepsin C gene revealed that the proband was homozygous for a missense mutation, c.415G-->A, which is predicted to result in the amino acid substitution p.G139R. Including our case, 4 families have been described as having PLS with MM, 3 of which are Japanese, implying a high incidence of melanoma development in Japanese PLS patients. We suggest that hereditary palmoplantar keratoderma (PPK) in Japanese patients might be predisposed to MM. A literature review revealed that in 18 cases of MM-associated PPK, 13 (76%) were Japanese, suggesting a high incidence of MM in Japanese PPK patients. This tendency might be attributable to the high frequency of acral lentiginous melanoma in Japanese subjects, in contrast to a lower frequency of this subtype in Caucasians.

Mutations in ichthyin a new gene on chromosome 5q33 in a new form of autosomal recessive congenital ichthyosis.

We report the genomic localization by homozygosity mapping and the identification of a gene for a new form of non-syndromic autosomal recessive congenital ichthyosis. The phenotype usually presents as non-bullous congenital ichthyosiform erythroderma with fine whitish scaling on an erythrodermal background; larger brownish scales are present on the buttocks, neck and legs. A few patients presented a more generalized lamellar ichthyosis. Palmoplantar keratoderma was present in all cases, whereas only 60% of the patients were born as collodion babies. Six homozygous mutations including one nonsense and five missense mutations were identified in a new gene, ichthyin, on chromosome 5q33 in 23 patients from 14 consanguineous families from Algeria, Colombia, Syria and Turkey. Ichthyin encodes a protein with several transmembrane domains which belongs to a new family of proteins of unknown function localized in the plasma membrane (PFAM: DUF803), with homologies to both transporters and G-protein coupled receptors. This family includes NIPA1, in which a mutation was recently described in a dominant form of spastic paraplegia (SPG6). We propose that ichthyin and NIPA1 are membrane receptors for ligands (trioxilins A3 and B3) from the hepoxilin pathway.

A novel mutation of keratin 9 in a large Chinese family with epidermolytic palmoplantar keratoderma.

BACKGROUND: Epidermolytic palmoplantar keratoderma (EPPK) is an autosomal dominant inherited skin disorder characterized by diffuse yellow thickening of the skin of the palms and soles, sharply bordered with erythematous margins. Histologically and ultrastructurally, EPPK presents cytolysis of keratinocytes and abnormal aggregation of tonofilaments in the suprabasal layers of the epidermis. To date, 15 different mutations of the keratin 9 gene (KRT9) have been demonstrated to cause most cases of EPPK. OBJECTIVES: To identify the KRT9 mutation in a large Chinese family with EPPK. METHODS: Denaturing high-performance liquid chromatography (DHPLC), DNA sequencing and allele-specific polymerase chain reaction (AS-PCR) were used to screen exon 1 of the KRT9 gene for sequence variations. RESULTS: The DHPLC elution profiles of the DNA fragments amplified from the affected samples differed from those obtained from unaffected individuals, indicating that a sequence variation existed within the analysed fragment of KRT9. DNA sequencing revealed a novel insertion-deletion mutation in the exon 1 of KRT9, 497delAinsGGCT, resulting in the change of tyrosine(166) to tryptophan and leucine (Y166delinsWL). AS-PCR confirmed the mutation was not a common polymorphism. CONCLUSIONS: The results suggest the molecular basis of EPPK in this Chinese family and provide further evidence that mutations in the helix initiation motif of keratin 9 underlie Chinese EPPK.

Epidermolytic palmoplantar keratoderma in a Hispanic kindred resulting from a mutation in the keratin 9 gene.

Epidermolytic palmoplantar keratoderma (EPPK) is a localized keratinization disorder caused by mutations in the highly conserved coil 1A domain of the keratin 9 gene, KRT9. We present a Hispanic pedigree spanning three generations, with affected individuals in all generations. Using polymerase chain reaction amplification and direct sequencing we demonstrated a previously reported missense mutation in KRT9, which is expressed almost exclusively in the skin of palms and soles. The C-->T missense mutation R162W changes a basic amino acid (arginine) to a neutral amino acid (tryptophan). We describe this mutation in a Hispanic pedigree with EPPK for the first time, extending the finding of this mutation in other genetic backgrounds, and demonstrating the prevalence of this mutation in diverse populations.

Keratosis punctata of the palmar creases: case report and prevalence study in Caucasians.

Keratosis punctata of the palmar creases (KPPC) is a variant of keratosis punctata of palms and soles in which lesions are confined to palmar creases. We present a patient with KPPC and study the prevalence of the disease in Caucasians. The survey included 1,001 white patients, that were examined for palmar lesions. We could not find any case that fulfilled the diagnostic criteria for KPPC. We conclude that KPPC is a rare disease among Caucasians but rather common in the black race.

Punctate keratoses of the palms and soles and keratotic pits of the palmar creases.

Punctate keratoses of the palms and soles and keratotic pits of the palmar creases are frequently confused. A prospective study of 283 patients revealed a prevalence of 11% and 3%, respectively, in a metropolitan county hospital dermatology clinic. Punctate keratoses of the palms and soles and keratotic pits of the palmar creases are similar in size, number of lesions per palm, aggravation by trauma, and predominance in blacks and in men. These entities are different in appearance, distribution, age at onset, prevalence, symptoms, and prognosis. Punctate keratosis of the palms and soles and keratotic pits of the palmar creases should be considered independent entities. To help eliminate confusion, we propose that punctate keratoses refer only to the hyperkeratotic papules scattered diffusely in the palms and occasionally in the soles and that keratotic pits of the palmar creases refer only the hyperkeratotic, conical depressions confined to the palmar creases.

Keratosis punctata of the palmar creases.

We compared the prevalence of keratosis punctata of the palmar creases among populations living in Belgium, Togo, Peru and the United Arab Emirates. It appears that black Africans and Hindous (prevalence 1 to 2%) are more often affected than Latin Americans (prevalence less than 0.1%). The disease was not seen among Europeans and Arabs. Histologically, the lesions consist of a marked hyperkeratosis located at the site of acrosyringia. The disease should therefore be considered as a sweat gland disorder.