Mutation analysis of type Ⅱ hair keratin gene in a pedigree with monilethrix

Objective To investigate the mutation of type Ⅱ human hair basic keratin (hHb) gene in a family with monilethrix.Methods Scanning electron microscopy was used to observe the structure of hair shafts.With informed consent,blood samples were drawn from affected and unaffected membets in this family,as well as from 50 healthy controls.Genomic DNA was isolated from these samples.The exon 1 and exon 7 of hHb1,hHb3 and hHb6 were amplified by polymerase chain reaction (PCR).All the PCR products were sequenced directly using ABI3730 automated sequencer.DNA sequence alignment was carried out with BLAST software.Results A typical beaded appearance was observed in affected hairs by using scanning electron microscopy.There were obvious longitudinal ridges and sulcuses in hair node.and hair cuticles were irregularly shaped.Most cortex and medullary substance were absent in affected hairs of a patient.After sequence alignment,a G1289A point mutation in exon 7 of hHb6 gene,which led to a substitution of arginine for glutamide at codon 430,was detected in affected members of this family,but not in unaffected family members or 50 unrelated human controls.No mutation was observed in exon 1 or exon 7 of hHb1 and hHb3 gene or exon 1 of hHb6 gene.Conclusion The missense mutation of R430Q is a novel mutation.which may be associated with the pathogenesis of monilethrix in this pedigree.     

Mutation analysis of type Ⅱ hair keratin gene in a pedigree with monilethrix

Objective To investigate the mutation of type Ⅱ human hair basic keratin (hHb) gene in a family with monilethrix.Methods Scanning electron microscopy was used to observe the structure of hair shafts.With informed consent,blood samples were drawn from affected and unaffected membets in this family,as well as from 50 healthy controls.Genomic DNA was isolated from these samples.The exon 1 and exon 7 of hHb1,hHb3 and hHb6 were amplified by polymerase chain reaction (PCR).All the PCR products were sequenced directly using ABI3730 automated sequencer.DNA sequence alignment was carried out with BLAST software.Results A typical beaded appearance was observed in affected hairs by using scanning electron microscopy.There were obvious longitudinal ridges and sulcuses in hair node.and hair cuticles were irregularly shaped.Most cortex and medullary substance were absent in affected hairs of a patient.After sequence alignment,a G1289A point mutation in exon 7 of hHb6 gene,which led to a substitution of arginine for glutamide at codon 430,was detected in affected members of this family,but not in unaffected family members or 50 unrelated human controls.No mutation was observed in exon 1 or exon 7 of hHb1 and hHb3 gene or exon 1 of hHb6 gene.Conclusion The missense mutation of R430Q is a novel mutation.which may be associated with the pathogenesis of monilethrix in this pedigree.     

一个表皮松解性掌跖角化病家系的KRT1基因突变分析

目的 探讨一个中国汉族人表皮松解性掌跖角化病(EPPK)家系的角蛋白基因KRT1、KRT9、KRT10突变情况.方法 收集1个EPPK家系的临床资料,提取外周血DNA,通过PCR扩增角蛋白KRT1、KRT9、KRT10基因编码区的全部外显子及其侧翼序列并测序,以表型正常家系成员及50例健康人为正常对照.结果 发现家系内6例患者均存在KRT1基因错义突变c.1436T>C,导致第479位的异亮氨酸被苏氨酸取代(I479T),在家系中6例正常人及50例对照者未发现上述突变.结论 错义突变KRTI的c.1436T>C可能为导致该家系临床表型的主要原因.本例为国内首次发现的KRT1突变引起的EPPK家系.

Abstract：

Objective To analyze the mutations in keratin 1 (KRT1), KRT9 and KRT10 genes in a Chinese family with epidermolytic palmoplantar keratoderma (EPPK). Methods Clinical data were collected from a family with EPPK. Genomic DNA was extracted from the peripheral blood of 12 family members, including 6 patients and 6 unaffected members, as well as from 50 unrelated normal human controls. PCR was performed to amplify all the exons and flanking sequences of KRT1, KRT9 and KRT10 genes followed by DNA sequencing.Results A missense mutation C.1436T > C was found in the highly conserved helix termination motif of KRT1 gene of all the patients, resulting in a substitution of isoleucine by threonine at position 479 of the KRT1 protein. No mutation was found in the unaffected members or unrelated controls. Conclusions The missense mutation C.1436T > C in K.RT1 gene is likely to be the main cause of the phenotype of EPPK in this family.This is the first report of a pedigree with KRT1 gene mutation-induced EPPK in China.     

X-性联锁遗传鱼鳞病一家系STS基因研究

研究X-性联锁遗传鱼鳞病(XLI)一家系基因突变情况,检测基因突变与临床表现的关系,为进一步开展基因诊断和基因治疗奠定基础.抽取该家系中患者、正常人及与这些家系无关的100例正常人的外周血,提取外周血基因组DNA.应用PCR方法扩增外周血基因组DNA类固醇硫酸酯酶(STS)基因的第1、2和10外显子.结果:该家系中的患者STS基因全部缺失,家系中正常人和与该家系无关的100例正常人未发现这种缺失.该缺失引发出XLI特有的皮肤病变.     

显性营养不良型大疱性表皮松解症COL7A1基因突变分析

Objective: Dystrophic epidermolysis bullosa is an autosomal dominant or recessive disorder caused by mutations in the gene encoding type Ⅶ collagen (COL7A1 gene). To detect the mutation of COL7A1 in a DEB family. Methods: We performed full exon sequencing on DNA of the proband, and verified the COL7A1 mutation site of her sister by Sanger sequencing. Results: The proband and her sister had the same COL7A1 genotype, and the point mutation on exon 86 was c.6761G>A (p.Gly2254Glu). Conclusion: A new mutation locus of DEB family COL7A1 gene is found, which has not been reported in China at present. © 2022 China Journal of Leprosy and Skin Diseases. All rights reserved.     

X-连锁遗传性鱼鳞病的类固醇硫酸酯酶基因中一个新的点突变

大约90％的X-连锁遗传性鱼鳞病(XLI)患者,完全或部分缺失X染色体上的类固醇硫酸酯酶(STS)基因。仅有少数患者的STS基因发生点突变。该文作者根据Ballabio等方法运用聚合酶链反应(PCR)检测了9例日本XLI患者的STS基因,其中8例STS基因完全缺失。1例显示了STS基因的PCR扩增。经PCR单链构象多态性分析,表明这例患者的STS基     

两个X连锁鱼鳞病家系中类固醇硫酸酯酶基因缺失

检测2个中国X连锁鱼鳞病家系中的基因突变。用PCR方法扩增类固醇硫酸酯酶(STS)基因的10个外显子，并对扩增产物进行测序。第一个家系中先证者的STS基因6、7外显子缺失，第二个家系先证者的整个STS基凶缺失。本研究明确了这两个家系中的基因突变，从而为这两个家系的后代进行产前诊断提供了可能。     

X性联锁遗传鱼鳞病一家系的STS基因研究

目的 研究一 X性联锁遗传鱼鳞病(XLI)家系基因突变,探讨基因突变与临床表现的关系,为进一步开展基因诊断和基因治疗奠定基础。方法 应用PCR方法扩增家系中的先证者及其母亲及与该家系无关的50例正常人外周血基因组DNA STS基因的第一外显子和第十外显子。以角蛋白hHb6为引物,作内对照。结果 家系中先证者的STS基因全部缺失,而先证者之母和与该家系无关的50例正常人未发现缺失。先证者及先证者之母的内对照引物PCR扩增后都有产物。结论 该XLI家系存在STS基因缺失,该缺失引发出XLI特有的皮肤病变。     

应用多重连接探针扩增技术检测X-性连锁鱼鳞病一家系STS基因

目的：检测X-性连锁鱼鳞病一家系STS基因突变情况。方法：提取先证者(男，31岁)及其父母外周血DNA，父母均无鱼鳞病临床表现，运用多重连接探针扩增技术检测所有成员的STS基因是否存在外显子缺失，若无外显子缺失，运用聚合酶链式反应特异性扩增STS基因，检测是否存在基因突变。结果：家系中先证者为STS基因半合子缺失，其母为STS基因杂合子缺失，其父亲未发现STS基因突变。家系中仅先证者出现鱼鳞病的临床表现。结论：STS基因缺失是该X-性连锁鱼鳞病患者发病的遗传因素。     

遗传性皮肤病

20 0 5 0 1 41　X性联锁遗传鱼鳞病一家系的STS基因研究 /刘安 (西安交大二院皮肤科 )…∥中国皮肤性病学杂志 . 2 0 0 4,1 8(7) . 40 3～ 40 5用PCR方法扩增一家系中先证者和其母亲及与该家系无关的 5 0例正常人外周血基因组DNASTS基因的第 1外显子和第 1 0外显子。结果先证者的STS基因全部缺失 ,其母及 5 0例正常人未发现缺失 ,先证者及其母亲的内对照引物PCR扩增后都有产物。认为这一X性联锁遗传鱼鳞病 (XLI)家系存在STS基因缺失 ,该缺失引发出XLI特有的皮肤病变。图 3参 1 1　 (汤亚娥 )2 0 0 5 0 1 42　板层状鱼鳞病患者谷…     

四种遗传性鱼鳞病基因型与临床表型的相关性分析

目的对四种鱼鳞病(寻常型鱼鳞病;X性-联鱼鳞病;板层状鱼鳞病;大疱性鱼鳞病)的致病基因进行精细定位,并分析其基因型与临床表型的关系。方法对四种鱼鳞病各1例患者进行临床表型分析以及外周血DNA直接测序检测鱼鳞病FLG基因、STS基因、TGM1基因和K1,K10角蛋白基因的突变位点。结果①寻常型鱼鳞病患者在FLG基因的外显子5的第278位有G-T突变,613位有G-A突变。②板层状鱼鳞病患者TGM1基因外显子3的第504位碱基有C-T突变,使第142位氨基酸由精氨酸(R)转变为半胱氨酸(C),即R142C错义突变;外显子7的第1122位碱基有C-T突变,使348位氨基酸由精氨酸(R)突变为终止密码(R348X),导致其编码的蛋白缺失了C端的470个氨基酸。③X-性联鱼鳞病患者STS基因完全缺失。④大疱性鱼鳞病患者外显子5的第242碱基存在A-C突变,外显子6的第599位碱基均存在A-G突变,导致K1蛋白第633位氨基酸由赖氨酸(Lys)变为精氨酸(Arg)。结论鱼鳞病患者临床表型的不同与致病基因的突变位点密切相关。     

Deletion of distal promoter of VCXA in a patient with X-linked ichthyosis associated with borderline mental retardation

BACKGROUND: X-linked ichthyosis (XLI) is caused by deficiency of steroid sulfatase (STS) activity. About 90% XLI patients have large deletions involving the entire STS gene and flanking regions. Recently, VCXA, which is located approximately 0.7Mb telomeric to the STS gene, was reported as a candidate gene for mental retardation (MR) in patients with XLI. OBJECTIVE: To delineate the X-chromosomal deletion of a XLI patient with borderline mental retardation. METHODS: We carried out FISH analysis to show that the whole STS gene is deleted, and PCR analysis for fine-scale deletion mapping. RESULTS: The deleted segment is approximately 1.6Mb in size, and includes the entire STS and VCXB1 genes. VCXA itself is intact, but its promoter is deleted. CONCLUSION: A deletion that includes the VCXA promoter is associated with borderline mental retardation in a patient with XLI.     

Deletion pattern of the steroid sulphatase gene in Japanese patients with X-linked ichthyosis

Most caucasian patients with X-linked ichthyosis (XLI) reportedly display large genomic deletions involving the entire steroid sulphatase (STS) gene and flanking regions. In this study, we investigated the deletion patterns of the STS gene and flanking regions in 12 unrelated Japanese patients with XLI using the polymerase chain reaction method with 10 markers, including the 5' and 3' ends of the STS gene. Eleven of the 12 patients exhibited deletion of this entire gene, whereas the twelfth patient showed no evidence of deletion. In 10 of the 12 patients, the entire region from DXS1139 to DXF22S1 was deleted, the most common deletion pattern observed in caucasian patients, indicating that there are no racial or ethnic differences.     

Analysis of the VCX3A, VCX2 and VCX3B genes shows that VCX3A gene deletion is not sufficient to result in mental retardation in X-linked ichthyosis

BACKGROUND: X-linked ichthyosis (XLI), an inborn error of metabolism, is due to steroid sulphatase (STS) deficiency. Most patients with XLI harbour complete deletion of the STS gene and flanking sequences. The presence of low copy number repeats on either side of the STS gene seems to have a major role in the high frequency of these deletions. Some patients with XLI with terminal deletions of Xp22.3 involving marker DXS1139 and the STS gene show mental retardation (MR); VCX3A is the only gene located on this critical region. OBJECTIVES: To analyse the VCX3A, VCX, VCX2 and VCX3B genes in 80 unrelated Mexican patients with XLI with normal intelligence. METHODS: STS activity was measured in the leucocytes using 7-[3H]-dehydroepiandrosterone sulphate as a substrate. Amplification of the regions from telomeric DXS89 to centromeric DXS1134 including both extremes of the STS and the VCX3A, VCX, VCX2 and VCX3B genes was performed using polymerase chain reaction. RESULTS: No STS activity was detected in the patients with XLI (0.00 pmol mg(-1) protein h(-1)). We observed two different deletion patterns: the first group included 62 patients with deletion of VCX3A and VCX genes. The second group included 18 patients with breakpoints at several regions on either side of the STS gene not including the VCX3A gene. CONCLUSIONS: These data indicate that more complex mechanisms, apart from possible VCX3A gene participation, are occurring in the genesis of MR in XLI, at least in the sample of Mexican patients analysed.     

Exacerbation of X-linked ichthyosis phenotype in a female by inheritance of filaggrin and steroid sulfatase mutations

Background

X-linked ichthyosis (XLI) is a relatively common, recessive condition caused by mutations in the steroid sulfatase (STS) gene. Common loss-of-function mutations in the filaggrin gene (FLG) cause ichthyosis vulgaris and predispose individuals to atopic eczema.

Objective

To test the hypothesis that co-inheritance of FLG mutations can act as a genetic modifier in XLI.

Methods

An unusually severe XLI phenotype in addition to eczema and mild childhood asthma was investigated in a female Indian patient by fluorescent in situ hybridization (FISH) for the common STS gene deletion. Direct sequencing of the entire FLG gene was also performed.

Results

FISH analysis revealed that the proband was homozygous for the common STS genomic deletion mutation. Further investigation revealed a frame-shift mutation 3672del4 in the gene encoding filaggrin (FLG), leading to premature termination of profilaggrin translation. Interestingly, her father, who had a very typical mild presentation of XLI, did not carry this FLG mutation in addition to his STS deletion. Her mother was a heterozygous carrier of the FLG mutation and consistent with this, had mild symptoms of ichthyosis vulgaris; she was also a heterozygous carrier of the STS deletion.

Conclusion

This is the second reported case of the modifying effects of FLG null alleles on XLI and strengthens the hypothesis that filaggrin defects can synergize with STS deficiency to exacerbate the ichthyosis phenotype.     

Deletion patterns of the STS gene and flanking sequences in Israeli X-linked ichthyosis patients and carriers: analysis by polymerase chain reaction and fluorescence in situ hybridization techniques

BACKGROUND: Deletion of the entire steroid sulfatase (STS) gene is the most common molecular defect in X-linked ichthyosis (XLI) patients. Usually, additional flanking sequences are also missing. The aim of this study was to estimate the extent of deletions in an ethnically heterogeneous population of Israeli XLI patients. METHODS: Multiplex polymerase chain reaction (PCR) and fluorescence in situ hybridization (FISH) techniques were applied in the analysis of blood samples of 24 patients and amniotic cells of seven affected fetuses from 22 unrelated families. RESULTS: In 19 families, a large deletion of the 2-3 megabase was found. It included the whole STS gene and spanned adjacent areas up- and downstream between the loci DXS 1139 and DXS 1132. Two unrelated families of Iraqi ancestry had a partial deletion of the gene and its centromeric adjacent sequence. In another family, the telomeric end of the extragenic segment was only partially missing. Application of FISH on metaphase blood cells and interphase amniotic cells confirmed the diagnosis of XLI in all patients, except the three with partial intragenic deletion. In those cases, the remaining fraction of the gene was sufficient to provide a false negative result. Diagnosis of carriers and prenatal diagnosis in uncultured cells was applicable only by FISH. CONCLUSIONS: Our study revealed a remarkable heterogeneity in the deletion pattern among Israeli patients with XLI. This heterogeneity could not be attributed to specific ethnic groups because of the small size of the study group. More studies involving patients of various ancestries should be carried out. In addition, this study demonstrated the usefulness of the FISH technique in the prenatal diagnosis of fetuses with suspected XLI.     

X linked recessive ichthyosis: Current concepts

In the present review, we describe the most importantaspects of the X-linked ichthyosis(XLI) and make a compilation of the some historic details of the disease. The aim of the present study is an update of the XLI. Historical, clinical, epidemiological, and molecular aspects are described through the text. Recessive XLI is a relatively common genodermatosis affecting different ethnic groups. With a high spectrum of the clinical manifestations due to environmental factors, the disease has a genetic heterogeneity that goes from a point mutation to a large deletion involving several genes to produce a contiguous gene syndrome. Most XLI patients harbor complete STS gene deletion and flanked sequences; seven intragenic deletions and 14 point mutations with a complete loss of the steroid sulfatase activity have been reported worldwide. In this study, we review current knowledge about the disease.     

斑驳病一家系调查及基因突变研究

目的 探讨中国汉族斑驳病一家系的临床特征和基因突变情况。方法 对该家系临床资料进行收集、整理、照相存档及临床遗传学特征分析,并绘制系谱图。提取家系成员和正常人对照者外周血基因组DNA,采用PCR及DNA直接测序的方法对该家系进行基因突变检测。结果 该家系成员共73人。根据典型的临床特征,先证者及其他患者共14例均确诊为斑驳病,遗传方式为常染色体显性遗传。家系中患者均存在KIT基因13号外显子第1900位ATGA插入（1900insATGA）,导致第634位密码子处出现移码突变,KIT蛋白多肽翻译提前终止于第641位密码子。家系其他成员及50例正常人对照者未发现此突变。该突变位点此前未见报道。结论 一种新的KIT基因突变（1900insATGA）可能是引起该斑驳病家系临床表型的原因。