Novel mutation in MVK gene for co-occurrence of disseminated superficial actinic porokeratosis with porokeratosis ptychotropica

Two Novel and Three Recurrent Mutations in the Mevalonate Pathway Genes in Chinese Patients with Porokeratosis

Purpose

Porokeratosis (PK) is a chronic autosomal-dominant cutaneous keratinization disorder exhibiting clinical and genetic heterogeneity. Mevalonate decarboxylase (MVD), farnesyl diphosphate synthase (FDPS), phosphomevalonate kinase(PMVK), and mevalonate kinase genes(MVK), which encode the mevalonate pathway, are disease-causing genes in PK.

Patients and Methods

Data and blood samples were collected from two Chinese families and five sporadic patients with porokeratosis. Whole-exome and Sanger sequencing were performed to detect pathogenic gene mutation in the patients.

Results

Five heterozygous mutations were identified, including a novel FDPS stop-gain mutation c.438T>G (p.Tyr146Ter), a novel MVD missense mutation c.683G>C (p.R228P), and three previously reported MVD mutations: c.746T>C (p.F249S), c.875A>G (p.N292S), and c.1111_1113del (p.371_371del). The novel FDPS c.438T>G mutation was predicted as "disease-causing" (p = 1) by Mutation Taster. The other novel MVD c.683G>C was also predicted as "deleterious" (score = 0.00) by Sorting Intolerant From Tolerant (SIFT), "probably damaging" (score = 1) by PolyPhen2, and "disease-causing" (p = 0.999) by Mutation Taster.

Conclusion

Our results extended the mutation spectrum of mevalonate pathway genes in porokeratosis and provided useful strategies for a more accurate diagnosis and genetic counseling.

Porokeratoses-A Comprehensive Review on the Genetics and Metabolomics, Imaging Methods and Management of Common Clinical Variants

Porokeratosis is a heterogeneous group of keratinising disorders characterised by the presence of particular microscopic structural changes, namely the presence of the cornoid lamella. This structure develops as a consequence of a defective isoprenoid pathway, critical for cholesterol synthesis. Commonly recognised variants include disseminated superficial actinic porokeratosis, disseminated superficial porokeratosis, porokeratosis of Mibelli, palmoplantar porokeratosis (including porokeratosis palmaris et plantaris disseminata and punctate porokeratosis), linear porokeratosis, verrucous porokeratosis (also known as genitogluteal porokeratosis), follicular porokeratosis and porokeratoma. Apart from the clinical presentation and epidemiology of each variant listed, this review aims at providing up-to-date information on the precise genetic background, introduces imaging methods facilitating the diagnosis (conventional and ultraviolet-induced fluorescence dermatoscopy, reflectance confocal microscopy and pathology), discusses their oncogenic potential and reviews the literature data on the efficacy of the treatment used, including the drugs directly targeting the isoprenoid-mevalonate pathway.

Case Report: A Novel MVK Missense Mutation in the Sporadic Porokeratosis Ptychotropica in China

Porokeratosis ptychotropica (PPt) is a rare type of porokeratosis (PK) characterized by pruritic, reddish-brownish verrucous papules, and plaques usually around genital area or buttocks. Here, a case of a 70-year-old woman who was diagnosed as PPt was reported. The patient suffered from severe pruritic papules and plaques in the buttock region and pubis for 4 years. The skin lesions were giant, well-defined brown plaques with many satellite papules scattered around. Both clinical manifestations and histopathological features supported the diagnosis of PPt. In review of the identified mutation was found in patients with disseminated superficial actinic porokeratosis (DSAP) combined with PPt, while its unclear in PPt. To investigate the hypothesis that the variant reported in the present case report may played as an independent "likely pathogenic factor" of PPt. Consequently, a de novo missense pathogenic mutation in the MVK gene was identified in this case. Unexpectedly, it is a first report of a novel MVK mutation in sporadic PPt. This rare case suggested an isogenetic background between PPt and DSAP, which may help to explore the underlying pathogenesis of PPt.

Mixed porokeratosis with a novel mevalonate kinase gene mutation: A case report

BACKGROUND

Porokeratosis is a rare, acquired, or inherited disorder of keratinization. There are numerous clinical types of porokeratosis and they can coexist in one patient and multiple members of an affected family. However, coexistence of disseminated superficial actinic porokeratosis (DSAP) and porokeratosis ptychotropica (Ppt) is rare.

CASE SUMMARY

A 45-year-old man presented with long-standing skin lesions. Physical examination identified numerous small, brown 2-mm to 4-mm patches on his face and several hyperkeratotic, verrucous plaques on his trunk and extremities. His father and one of his brothers also had similar lesions for years. Skin biopsies indicated a cornoid lamella in the epidermis. We identified c.155G>A mutation in the mevalonate kinase (MVK) gene, which converted a serine residue to asparagine (p.Ser52Asn) and was causative for porokeratosis in this family. A clinicopathologic diagnosis of DSAP and Ppt with a novel MVK gene mutation was made. The hyperkeratotic plaques on the patient’s scrotum were completely removed more than 10 times using a microwave knife.

CONCLUSION

An unusual case of DSAP coexisting with Ppt harbored a novel MVK gene mutation also present in the patient’s family.