Clinical Feature Analysis And Polymorphisms Of Correlated Genes In North Chinese Han Keloid Population

IntroductionKeloids are fibrous overgrowths that develop at sites of cutaneous injury and are characterized by the deposition of excessive extracellular matrix collagen,synthesized by the increased number of fibroblasts.The excessive scar tissue proliferates beyond the boundaries of the original wound.Keloids are considered to be benign tumors and, unlike normal scars and hypertrophic scars,do not regress spontaneously,commonly recurring following excision.Although the cause of keloids is unknown,it is thought that they are due to a failure to turn off the healing process needed to repair broken skin and genetic factors influence susceptibility and modify progression.Marneros studied two families with an autosomal dominant inheritance pattern of keloids.One African-American family showed a high degree of variability in the extent of keloid formation between family members,whereas the second family from Japan showed a pattern of full penetrance and the formation of only small keloids.They performed a genomewide linkage search for genes predisposing to keloid formation in these two families and identified linkage to chromosome 2q23 for the Japanese family. The African-American family showed evidence for a keloid susceptibility locus on chromosome 7p11.The observed locus heterogeneity in autosomal dominant keloid disease is consistent with the clinical heterogeneity of this scarring disorder.This study provides the first genetic evidence for keloid susceptibility loci and serves as a basis for the identification of responsible genes.Keloid scar populations reported prevalence rates vary greatly all over,from Zaire to the England of 16%less than 1%,the prevalence rate of different races are also a huge difference,dark ethnic origin of patients with light-colored disease increased from 2:1 to 19:1 range.The majority of cases of keloid were distributed,but there are also gathered home situation.At a South Indian epidemiological survey of 1000 people has a family history in 1.9%,another study of 247 people shows that there is a family history of keloid patients accounted for 3.2%.Some keloid syndrome can also be the emergence of the merger,and also has a family history,such as Rubinstein-Taybi syndrome and syndrome Goeminne,but they are different diseases and keloids.Data indicate that the majority of foreign patients with no gender differences in keloid.The occurrence of keloids with age-related,usually is 10-30 years of age in China's north. There is still a lack of clinical epidemiological data Han keloid.Single nucleotide polymorphism(SNP) in recent years are the third generation of genetic markers,early disease risk assessment,early diagnosis and prevention as well as the corresponding treatment and many other applications have enormous value.In particular,single nucleotide polymorphisms are located in protein coding region and the SNP sequence of expression and regulation may have a specific function and can affect disease susceptibility.Matrix metalloproteinases(metal matrix proteinase,MMPs) are a family of highly conserved zinc ions dependent proteolytic enzymes.Extracellular matrix degradation are the main course of proteolytic enzymes,playing an important role in the process in cell migration,angiogenesis,wound healing,the infiltration and metastasis of malignant tumors.MMPs family has at least 17 members,according to the structure and different substrate affinity,MMPS mainly divided into 4 groups:①collagenase,MMP1 represented,the main digestionⅠ,Ⅱ,Ⅲ,Ⅶ,Ⅹcollagen and proteoglycans;②gelatinase,MMP2,MMP9,also known as gelatinase-A,B,the main digestiveⅣ,Ⅴ,Ⅶ,Ⅹcollagen and elastic fibers;③matrilysin(stromelysin) MMP3,MMP7,MMP10, MMP11,a key role in fibronectin,laminin,elastic fiber,Ⅲ,Ⅳ,Ⅵ,Ⅸcollagen and MMP1,MMP8,MMP9;④membrane-type MMP(membrane-type matrix proteinase) MT1-MMP,MT2-MMP,MT3-MMP,a major role in collagen typeⅣgelatinase, MMP2.The majority of MMPs significantly expressed in the physiological or pathological remodeling process.At present,there is a number of MMPs gene polymorphism can affect the structure and function of MMPs,fibrosis,inflammation and the development of disease.Human MMP-9 gene located in chromosome 20q12-13,research has found MMP-9 polymorphism,C-1562T and the CA-repeat.In this study,we adopt epidemiology study of 680 cases of Han nationality keloid cases,Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method and sequencing to study MMP-9 -1562C/T and IL-6 -174G/C gene polymorphisms of 120 cases of Han nationality keloid cases in North China and 180 cases of race and geographical matched normal controls.Investigating MMPg-1562C/T and IL-6 -174G/C gene polymorphism could provide clues to the genetic susceptibility of keloid and reveal the pathogenesis of keloid.Material and method1.Subjects(1).case group:Epidemiological investigations into 680 cases of patients with keloid for First Affiliated Hospital of China Medical University dermatology out-patient clinics and hospitalized patients with the clinical diagnostic criteria:scar tissue over the scope of the original injury,the course is greater than 1 year.120 keloid patients were diagnosed in Department of Dermatology,First Hospital of China Medical University,conforms to the clinical diagnosis standard:excessive scar tissue proliferates beyond the boundaries of the original wound and the course of disease is more than 1 year.All patients were unrelated North China Han person,in which male 54 examples,feminine 66 examples,age of onset is 12-52 year old,average age is 26.4(±5.9) years old.(2).Normal control group:180 examples,a random selection of volunteers for health examination,include 84 male and 96 female.The average age is 24.3(±2.7) years old,no blood relationship between them,and the keloid medical history and family history were excluded.2.Materials10%SDS,EDTA,proteinase K,Tris saturated phenol,chloroform,sodium acetate, alcohol,TE buffer,agarose,8%denatured polyacrylamide solution,LA Taq enzyme.3.Methods(1) Polymerase chain reaction(PER)(2) The polymerase chain reaction - restrictive fragment length polymorphism (PCR-RFLP) method to genotyping the allele type.(3) Direct sequencing.4.Statistical Analysis To determine whether genotype was in Hardy-Weinberg equilibrium,aχ2 test was performed.The genotype frequency and the allele frequency of three genes compared byχ2,and odds ratio(OR) and 95%confidence interval(CI) indicate the relative risk. Statistical analyses were performed in SPSS 13.0.Result1.Results of epidemiology studyThere is no gender differences in China north Han keloid.The peak of keloids is usually 10-30 years of age.2.Results of MMP-9 -1562C/T gene polymorphism research(1) Keloid group and the normal population control group MMP-9 -1562C / T genotype distribution of the balance in line with the Hardy-Weinberg law.(2) Keloid group MMP-9-1562C / T allele frequency compared with normal control group,the difference has statistical significance(P＜0.05).3.Results of I1-6 - 174G/C gene polymorphism research(1) Keloid group and the normal population control group I1-6 -174 G/C genotype distribution of the balance in line with the Hardy-Weinberg law.(2) Keloid group I1-6 -174G/C allele frequency compared with normal control group,the difference has no statistical significance(P＞0.05).Conclusion1.Epidemiological investigation showed that no gender differences in the incidence of keloid;incidence peak concentrated in the 10-30 years of age;have a family history of early onset of age;have a family history of multiple keloid-prone patients.2.Keloids and normal control group,the crowd MMP-9 -1562C/T allele frequency have reached the Hardy-Weinberg genetic equilibrium.3.MMP-9 gene T allele may be associated with the existence of the formation and development of keloids.4.Keloids and normal control group,the crowd I1-6 -174G/C allele frequency have reached the Hardy-Weinberg genetic equilibrium.5.I1-6 -174G/C polymorphism may not be associated with the existence of the formation and development of keloids.