Analysis Of Gene Mutations In Chinese Patients With Porokeratosis

Background:Porokeratosis（PK）is a rare and chronic autosomal dominant cutaneous keratinization disorder,which has a wide variety of clinical manifestations.In addition to the heterogeneity in clinical manifestations,genetic heterogeneity is also observed in PK.PK is characterized by one or more spread centrifugally annular lession with raised horny border and the central part of the lesion is smooth and dry,atrophy.PK is currently classified according to its different clinical manifestation,such as number,size,morphology and distribution of the histological into six clinical subtypes,including classic porokeratosis of Mibelli（PM）,disseminated superficial actinic porokeratosis（DSAP）,linear porokeratosis（LP）,porokeratosis punctata palmaris etplantaris（PPPP）,disseminated superficial porokeratosis（DSP）,and porokeratosis palmoplantariset disseminated（PPPD）.So far,the pathogenesis of PK has not been fully elucidated.With the rapid development of molecular genetics technology,the application of exome sequencing in the medical field is wider and wider.Up to date,mutations has been reported including five genes,mevalonate kinase（MVK）gene,mevalonate decarboxylase（MVD）gene,phosphomevalonate kinase（PMVK）gene and farnesyl diphosphate synthase（FDPS）gene that are all linked to porokeratosis.Although a significant genetic heterogeneity exists in PK,MVK and MVD remains the most common causative genes for porokeratosis.In this study,We collected 10 families and 4 sporadic cases with PK from the first affiliated hospital of soochow university.The probands of 10 families and 4 sporadic patients were diagnosed by asspcoate senior doctor based on the typical manifestations and histopathological findings.Then,we analyzed their clinical and hispathological features of patients.And we analysed four genes including MVK,MVD,PMVK and FDPS of 10 families and 4 sporadic patients with PK by DNA Sanger sequencing.In addition to this,We would predict the pathogenicity to all mission mutations by softwares SIFT and PolyPhen-2 Prediction.Objective:1.To analyze the clinical manifestations and pathological features of 14 cases with PK from China.2.To detect pathogenic mutations of MVK,MVD,PMVK and FDPS genes in 14 Chinese patients with PK.3.To analysis the pathogenicity of all the mission mutations.Methods:The clinical data of probands of 10 families and 4 sporadic cases with PK were retrospectively surveyed and the results of histopathology section,and hematoxylin-eosin staining in skin tissues were observed and analyzed.Genomic DNA were extracted from the peripheral blood of all cases.All the exons and their flanking intronic sequences of MVK,MVD,PMVK and FDPS genes were amplified by polymerase chain reaction（PCR）,and then DNA Sanger sequencing were performed in patients to screen the mutations in the gene.The software of SIFT prediction and PolyPhen-2 prediction were performed to analysis the pathogenicity of all the mission mutations.Result:1.All of the 14 porokeratosis patients,The sex ratio between male and female is 5:1.The average of patients is 27.07.According to its different clinical manifestation,there are seven DSAP patients,three DSP patients,three PM patients and one PM with LP patient,their presence was 50.00%,21.43%,21.43% and 7.14% respectively.The common pathologic of all tissues are cornoid lamella.2.We detect MVK gene mutations in two families probands,the mission mutation c.605G>A（7.14%）is identified in family 4 and the framesshift mutation c.387₃88delGATATinsC（7.14%）is identified in family 9.None of these mutations were found in 10 families and 50 unrelated controls.All of theses,c.605G>A was reported in our country,c.387₃88delGATATinsC was not reported in our country and foreign country.3.We detect MVD gene mutations in nine families probands,the mission mutation c.746T>C（42.86%）is identified in family 2,family 3,fanmily 6,family 8 and sporadic 14,c.238:C>T（7.14%）is identified in family 7 and the framesshift mutation c.1111₁113delATT（14.29%）is identified in family 5 and sporadic 12.None of these mutations were found in 10 families and 50 unrelated controls.All of theses,c.746T>C and c.1111₁113delATT were reported in our country,c.238:C>T was not reported in our country and foreign country.4.By the software of SIFT prediction and PolyPhen-2,we can know the mission mutations’ score:（1）MVK: c.605G>A（SIFT:Damaging 0,PolyPhen-2:probably/1）;（2）MVD:c.746T>C（SIFT:Damaging 0,PolyPhen-2:probably/0.994）.5.In our study,we failed to identify any mutations in MVK,MVD,PMVK and FDPS gene in the family 10 probands,sporadic 11 and sporadic 13.Conclusion:1.We confirmed three previously reported mutation c.605G>A,c.746T>C and c.1111₁113delATT.This result further indicated MVK and MVD are causative gene for porokeratosis.2.We reported two novel mutations c.387₃88delGATATinsC（MVK）and c.238:C>T（MVD）in family 9 and family 7 probands respectively.This study extended the mutation spectrum of MVK and MVD gene and provided further evidence for the study of PK.