Mutation analysis of the ADAR1 gene in dyschromatosis symmetrica hereditaria and genetic differentiation from both dyschromatosis universalis hereditaria and acropigmentatio reticularis

Dyschromatosis symmetrica hereditaria (DSH) (also called "reticulate acropigmentation of Dohi") is a pigmentary genodermatosis of autosomal dominant inheritance. We have clarified for the first time four pathological mutations of the double-stranded RNA-specific adenosine deaminase gene (ADAR1 or DSRAD) in four DSH pedigrees. In this paper, we report 16 novel mutations containing six missense substitutions (p.V906F, p.K1003R, p.G1007R, p.C1036S, p.S1064F, p.R1078C), two splice site mutations (IVS2+2T>G, IVS8+2T>A), six frameshift mutations (p.H216fs, p.K433fs, p.G507fs, p.P727fs, p.V955fs, p.K1201fs), and two nonsense mutations (p.R426X, p.Q600X) found in Japanese patients with DSH. We did not establish any clear correlation between the clinical phenotypes and the genotypes of ADAR1 gene mutations in our examination of 16 cases plus four pedigrees. None of the different mutations identified in our studies of 20 cases suggested any founder effect. Furthermore, we did not identify any mutations in the ADAR1 gene of three patients with dyschromatosis universalis hereditaria or three patients with acropigmentatio reticularis, indicating that the two diseases are completely different from DSH, although they have sometimes been suggested to be phenotypical variations of DSH.     

Ten novel mutations of the ADAR1 gene in Japanese patients with dyschromatosis symmetrica hereditaria

Dyschromatosis symmetrica hereditaria (DSH) is a pigmentary genodermatosis of autosomal-dominant inheritance. We have reported 20 different mutations of the adenosine deaminase acting on RNA 1 gene (ADAR1) in patients with DSH since we had clarified that the disease is caused by a mutation of the ADAR1 gene in 2003. In this study, we report 10 novel mutations responsible for DSH: p.Q102fsX123, p.T369fsX374, p.S664fsX677, p.R892L, p.I913R, p.R916Q, p.P990fsX1016, p.C1081S, p.C1169F, and p.K1187X.     

Mutational spectrum of the ADAR1 gene in dyschromatosis symmetrica hereditaria

Dyschromatosis symmetrica hereditaria (DSH) is a rare autosomal dominant cutaneous disorder characterized by a mixture of hyperpigmented and hypopigmented macules of various sizes on the extremities and caused by the mutations of adenosine deaminase acting on RNA1 (ADAR1) gene. We screened 14 unrelated families or sporadic cases for mutation in the full coding sequence of this gene. Eight novel heterozygous mutations of ADAR1 and four known mutations were identified, including four missense mutations (p.R26K, p.Y1192D, p.R916Q, p.R1155W), six frameshift mutations (p.N205fsX217, p.V211fsX217, p.V404fsX417, p.I914fsX927, p.L1053fsX1076, p.L1070fs1092), and two nonsense mutations (p.R474X, p.R1096X). Interestingly, we failed to detect any mutations of ADAR1 in one family. Including our data, there are now 93 different mutations reported in 105 independent patients that we have tabulated. From the review of clinical features in these reports, we found that the same mutation could lead to different phenotypes even in the same family and did not establish a clear correlation between genotypes and phenotypes. Finally this study is useful for functional studies of the protein and to define a diagnostic strategy for mutation screening of the ADAR1 gene.     

Six novel mutations of the ADAR1 gene in Chinese patients with dyschromatosis symmetrica hereditaria

BACKGROUND: Dyschromatosis symmetrica hereditaria (DSH) is a rare autosomal dominantly inherited dermatosis and characterized by a mixture of hyperpigmented and hypopigmented macules on the back of hands and feet. The DSH locus was mapped to chromosome 1q21 and subsequently pathogenic mutations were identified in the adenosine deaminase acting on RNA1 (ADAR1) gene in 2003. OBJECTIVE: In this study, we performed a mutation analysis of the ADAR1 gene in eight Chinese families and one sporadic patient with typical DSH. METHODS: PCR and direct sequencing of the ADAR1 gene were performed to identify and confirm the mutations in the eight families and the sporadic patient. RESULTS: Six novel and one known mutations were identified, including four missense mutations (p.K1105N, p.G1047R, p.F1099L, p.G1068R), two frameshift mutations (p.Q779fs-792x, p.P441fs-463x) and one nonsense mutation (p.R1096x). CONCLUSION: Six novel mutations were found in five unrelated families and one sporadic case, which have further improved our understanding on the role of ADAR1 in DSH. Interestingly, we failed to detect any mutations of ADAR1 in two families.     

遗传性对称性色素异常症三家系ADAR1基因突变检测

【摘要】 目的 探讨3个遗传性对称性色素异常症家系中ADAR1基因的突变情况。方法 收集血样,用PCR结合DNA直接测序的方法,检测3个家系中的患者、患者亲属及与家系无关的50例健康个体的ADAR1基因突变情况。 结果 所研究的3个家系中均存在ADAR1基因的异常。包括A及C家系中2个错义突变（c.1760A > G导致p.Y587C,c.3620G > T导致p.G1207V）,B家系中1个移码突变（c.2433-2434delAG）。3个家系中未患病个体和健康对照均未发现相应突变。 结论 3个ADAR1基因突变中,2个错义突变均为新突变,可能是导致遗传性对称性色素异常症发病的分子机制之一。     

Novel mutations of the RNA-specific adenosine deaminase gene (DSRAD) in Chinese families with dyschromatosis symmetrica hereditaria

Dyschromatosis symmetrica hereditaria (DSH) is an autosomal dominant skin disorder. It is also called "reticulate acropigmentation of Dohi" or "symmetric dyschromatosis of the extremities". The DSH locus has recently been mapped to chromosome 1q21 and pathogenic mutations were identified in the DSRAD gene encoding double-stranded RNA-specific adenosine deaminase in Japanese patients with DSH. We report here two novel point mutations, Q513X(1537C>T) and R916W(2746C>T) in the DSRAD gene identified in two Chinese families, respectively. These data suggest that mutations in DSRAD were also associated with DSH in Chinese. This is the first report on DSRAD as the causative gene of DSH in the Chinese population.     

A new arginine substitution mutation of DSRAD gene in a Chinese family with dyschromatosis symmetrica hereditaria

BACKGROUND: Dyschromatosis symmetrica hereditaria (DSH) is a pigmentary genodermatosis of autosomal dominant inheritance characterized by a mixture of hyperpigmented and hypopigmented macules distributed on the dorsal aspects of the hands and feet. To date, only three articles testified that DSH is caused by the mutations of DSRAD gene (also called ADAR1) encoding for RNA-specific adenosine deaminase. OBJECTIVE: To identify mutations of DSRAD as the disease-causing gene and recognize different mutations giving a clue to insight into the mechanism of DSH. METHODS: We collected a Chinese DSH family consisting of a total of 11 individuals including five DSH patients (three males and two females). The whole coding region of DSRAD was amplified by polymerase chain reaction and products analyzed by direct sequencing. RESULTS: We detected a transition, 3463 C>T, leading to a missense mutation (R1155W) in genomic DNAs of five patients, and the point mutation was not found in normal individuals in this DSH family and in 100 unrelated, population-match control individuals. CONCLUSION: Our data suggests that R1155W missense mutation is a new mutation in exon 15 of DSRAD gene and further testify that DSRAD gene is the pathogenic gene of DSH.     

一对称性色素异常症家系ADAR基因突变分析及产前诊断

 目的:通过对一中国汉族对称性色素异常症(DSH)家系行ADAR基因突变检测,分析其致病性及诊断胎儿是否为DSH患者。方法：收集家系成员的临床资料和血样,应用高通量测序方法进行测序分析,应用聚合酶链反应(PCR)扩增结合Sanger测序对ADAR基因所有编码区进行测序,分别检测家系中2例患者(先证者及其父亲)、1例胎儿和8例正常人的突变情况。结果：该家系中2例患者及胎儿均携带ADAR基因c.613C>T(p.Q205X)位点杂合变异,另外8例未患病的家系成员均未发现上述突变。结论：ADAR 基因c.613C>T(p.Q205X)为引起该家系发生DSH的突变位点,而不是单核苷酸多态性(SNP)。该结果拓展了ADAR基因突变谱,为遗传性对称性色素异常症基因诊断和产前诊断提供参考和帮助。     

遗传性对称性色素异常症一家系ADAR1基因突变检测

目的：检测1例中国汉族遗传性对称性色素异常症家系ADAR1基因突变情况。方法：收集该家系内的2例患者及2名表型正常者的临床资料和血样,提取外周血基因组DNA,PCR扩增后进行DNA测序。结果：该家系2例患者均存在ADAR1基因第13号外显子c.3232C〉T突变（p.R1078C）,而在该家系内表型正常的个体以及100名正常对照中均未发现该突变。结论：该DSH家系内ADAR1基因c.3232C〉T突变可能与DSH发病有关。     

遗传性对称性色素异常症2例ADAR基因突变分析及家系调查

【摘要】 目的 对2个遗传性对称性色素异常症（DSH）家系进行家系调查并基因检测。方法 收集2家系DSH先证者及其家族成员的临床资料,同时采集先证者及其父母和100名无亲缘关系健康对照的外周血标本,应用二代皮肤靶向测序包检测基因突变,再用Sanger测序验证。结果 例1男,双手背、足背5岁时出现散在粟粒大小色素沉着斑和色素减退斑,母亲有类似表现。患者及母亲ADAR基因5号外显子检测到1个新的c.1970dupT（p.F657fs）杂合移码突变,父亲未检测到该突变。例2男,面颈部、腰背部、臀部、双下肢及双手足背夹杂分布米粒至黄豆大小褐色沉着斑和色素减退斑,父亲有类似表现,患者及父亲ADAR基因7号外显子检测到1个已知c.2433_2434delAG（p.T811fs）杂合移码突变,母亲未检测到该突变。无亲缘关系的100例健康对照均未发现上述突变。结论 本研究在DSH患者中检测到1个新的ADAR突变位点c.1970dupT。     

Six novel mutations of the ADAR1 gene in patients with dyschromatosis symmetrica hereditaria: histological observation and comparison of genotypes and clinical phenotypes

Dyschromatosis symmetrica hereditaria (DSH), is a pigmentary genodermatosis of autosomal dominant inheritance. Since we clarified that the disease is caused by a mutation of the adenosine deaminase acting on the RNA 1 gene (ADAR1) in 2003, the molecular pathogenesis of a peculiar clinical feature of the disease has been expected to be clarified. We examined five familial cases and one sporadic case of Japanese families with DSH. The mutation analyses were done with single-strand conformation polymorphism/heteroduplex (SSCP/HD) analysis and direct sequencing of ADAR1. The DNA analysis of each patient revealed one missense mutation (p.F1091S), two nonsense mutations (p.C893X, p.S581X) and three frame-shift mutations (p.E498fsX517, p.F1091fsX1092, p.L855fsX856). Visual and electron microscopic findings showed abundant melanin pigment deposited all over the basal layer, and enlarged melanocytes with long dendrites located in the pigmented lesions with small or immature melanosomes scattered sparsely in the cytoplasm, but in the adjacent keratinocytes many small melanosomes were singly dispersed or aggregated. The hypopigmented areas showed little melanin deposition and reduced numbers of melanocytes in which much degenerative cytoplasmic vacuole formation could be observed by electron microscopy. Herein, we report six cases of DSH with six novel mutations. The variety of their clinical phenotypes even in the pedigree may suggest the presence of factors other than the ADAR1 gene influencing the extent of the clinical skin lesion. Microscopic findings suggest that the clinical appearance must have developed directly by melanocyte variations mainly induced by the ADAR1 gene mutations.     

遗传性对称性色素异常症一家系A-DAR1基因新突变

目的:确定一遗传性对称性色素异常症家系ADAR1基因的突变位点。方法:提取家系中2例患者、2名表型正常者及50名与本家系无关的正常对照外周血DNA,采用PCR技术扩增ADAR1基因所有编码区并进行测序。结果:该家系中2例患者均存在ADAR1基因错义突变(c.662CT),导致p.P211R改变,家系中2名未患病的个体和50名健康对照均未发现上述突变。结论:ADAR1基因c.662CT错义突变是导致该家系发生DSH的致病性突变,在国内外属首次报道。     

一个遗传性对称性色素异常症家系ADAR1基因突变分析

目的 检测1个遗传性对称性色素异常症家系中ADAR1基因的突变位点。方法 提取一遗传性对称性色素异常症家系成员（5例患者,3例非患者）和100例无血缘关系的健康对照外周血标本,PCR扩增ADAR1基因全部15个外显子序列并测序,参考Genebank中ADAR1基因标准序列对比分析突变位点。结果 该家系5例患者ADAR1基因2号外显子第1 420位碱基C突变为T,为无义突变,即C.1420C > T（p.Arg474X）,家系其他健康成员和100例无关健康人中未发现此突变。结论 该遗传性对称性色素异常症家系的致病突变为ADAR1基因C.1420C > T无义突变。     

Dyschromatosis symmetrica hereditaria associated with neurological disorders

Dyschromatosis symmetrica hereditaria (DSH) is a pigmentary genodermatosis of autosomal dominant inheritance caused by a mutation of adenosine deaminase acting on the RNA 1 gene (ADAR1). It is characterized by a mixture of hyper‐ and hypopigmented macules on the back of the hands and feet. The pathomechanism by which the ADAR1 gene mutation induces DSH has not been clarified yet. We experienced an 11‐year‐old male DSH patient associated with dystonia, mental deterioration and brain calcification, who had a mutation of p.G1007R in the ADAR1 gene. This mutation had already been reported in a patient with similar neurological symptoms by Tojo et al. Additionally, a patient with DSH associated with torsion dystonia was reported by Patrizi et al., but gene analysis was not carried out. Only three cases with neurological disorders have been reported, although more than 50 mutations of the ADAR1 gene causing DSH have been reported and none of them had any neurological symptoms. Therefore, we suggest that neurological disorders rarely develop in DSH.     

Two novel frameshift mutations of the DSRAD gene in Chinese pedigrees with dyschromatosis symmetrica hereditaria

Background Dyschromatosis symmetrica hereditaria (DSH) is an autosomal dominant disorder characterized by a mixture of hyperpigmented and hypopigmented macules localized on the back of the extremities and caused by the mutations in the DSRAD gene. Methods Two Chinese pedigrees of typical DSH were subjected to mutation detection in DSRAD. Direct sequencing of all PCR products of the whole coding regions of DSRAD was performed to identify the mutation. Results The c.1615delG (p.V539fs) mutation was found in the affected members but not in the healthy individuals in family 1 and the c.ins1372‐9 CCACAGAT (p.D458fs) mutation was found in patients but not in the healthy members of family 2. Conclusion Our study found two novel frameshift mutations in the DSRAD gene. We add new variants to the knowledge of DSRAD mutations in DSH.     

遗传性对称性色素异常症2例基因诊断

目的:鉴定1例遗传性对称性色素异常症(dyschromatosis symmetrica hereditaria,DSH)患者ADAR1(adenosine deaminase acting on RNA1)基因突变,并对该家系中一临床不典型病例进行基因诊断.方法:采集1例DSH患者及家族成员的外周血,应用直接测序的方法检测突变位点.结果:在患者10号内含子区域检测到1个剪接位点突变(c.2886-5T>C).另外,对该家系中临床表现不典型的患者,基因测序结果支持该病的诊断.结论:该研究检测到1例新的剪接位点突变,异常剪接方式为外显子的删除.并明确了该家系中临床不典型患者的诊断,在Wood灯下进一步确定了其临床表型.     

Two frameshift mutations in the RNA-specific adenosine deaminase gene associated with dyschromatosis symmetrica hereditaria

OBJECTIVE: To report and analyze the mutations of the double-stranded RNA-specific adenosine deaminase (DSRAD) gene in 2 Chinese pedigrees with dyschromatosis symmetrica hereditaria (DSH). DESIGN: Pedigree study. SETTING: Anhui province of China. PATIENTS: Two Chinese families, consisting of 19 individuals (family 1) and 5 individuals (family 2). INTERVENTIONS: We directly performed mutation detection of the DSRAD gene in 2 Chinese families with DSH by sequencing. The whole coding region of DSRAD was amplified by polymerase chain reaction, and products were analyzed by direct sequencing. MAIN OUTCOME MEASURES: Frameshift DSRAD gene mutations. RESULTS: The c.3513insC (Arg1171fs) mutation was found in all patients but not in the healthy individuals from family 1, and the c.3220_3224delGCATC (Gly1073fs) mutation was found in 2 patients but not in the healthy members of family 2. These 2 mutations were not found in 96 unrelated control individuals. CONCLUSION: Our data suggest that these 2 novel frameshift mutations in the DSRAD gene could cause DSH in the Chinese Han population and add new variants to the repertoire of DSRAD mutations in DSH.     

A new mutation of the double-stranded RNA-specific adenosine deaminase gene in a family with dyschromatosis symmetrica hereditaria

BACKGROUND: Dyschromatosis symmetrica hereditaria (DSH) is a pigmentary genodermatosis characterized by a mixture of hyperpigmented and hypopigmented macules localized on the back of the extremities and caused by mutations in the double-stranded RNA-specific adenosine deaminase (DSRAD) gene. OBJECTIVE: To identify gene mutations of DSRAD in patients with DSH. METHODS: A Chinese pedigree of typical DSH was subjected to mutation detection in DSRAD. Direct sequencing of all PCR products of the whole coding regions of DSRAD was performed to identify the mutation. RESULTS: A missense mutation 2747G-->T in the DSRAD gene was found in the affected members but not in the healthy individuals in this family and in 50 unrelated controls. CONCLUSION: Our study found a novel missense mutation in exon 9 of the DSRAD gene. We add new variants to the knowledge of DSRAD mutations in DSH.