X连锁少汗性外胚叶发育不良一家系ED1基因突变检测研究

目的:研究X连锁少汗性外胚叶发育不良一家系患者的临床表现及其致病原因.方法:在患者家系调查的基础上,收集家系中患者和正常人的血样,并采集正常对照血样100份,采取聚合酶链反应技术对ED1基因进行扩增,并对其产物进行测序.结果:该家系中所有的患者均表现为汗腺缺乏或减少,毛发稀少,全部或部分牙齿缺损.ED1基因第9号外显子存在1个22个碱基缺失突变.结论:该家系发病是由ED1基因突变所致,其发病的基因型和表型之间的关系有待于进一步研究.     

X连锁少汗性外胚叶发育不良家系基因突变检测

目的:检测1例3月龄少汗性外胚叶发育不良男性患儿及其家族成员少汗性外胚叶发育不良(ED1)基因的突变.方法:提取家系成员白细胞中的DNA,设计引物特异扩增ED1基因的外显子及其侧翼区域并测序,与正常人的测序结果进行比较.结果:患儿ED1基因第466位碱基由胞嘧啶变为胸腺嘧啶,使翻译产物中相应的氨基酸由精氨酸变为半胱氨酸,即R156C.先证者母亲为杂合子,父亲未检测到突变.结论:R156C导致了X连锁少汗性外胚叶发育不良在该家系中的传递.     

A frameshift mutation of the ED1 gene in sibling cases with X-linked hypohidrotic ectodermal dysplasia

X-linked hypohidrotic ectodermal dysplasia (XLHED; MIM 305100) is characterized by the absence or hypoplasia of hair, teeth, and sweat glands. The ED1 gene was identified as a responsive gene for XLHED. The patients were 2 Japanese brothers. Both had the same mutation in exon 1 of the ED1 gene, i.e. C deletion at nucleotide 49, which induced a frameshift starting from amino acid 17 and made a stop codon at amino acid 56, encoding the transmembrane site. The mutation caused the extracellular domain of ectodysplasin A to be completely absent. Their mother had a heterozygous allele; she congenitally lacked 1 tooth, and incisors appeared conical in form.     

Mutation in the ED1 gene, Ala349Thr, in a Korean patient with X-linked hypohidrotic ectodermal dysplasia developing de novo

Hypohidrotic ectodermal dysplasia (HED) is a very rare disease characterized by the virtual absence of eccrine glands, dry skin, scanty hair, and dental abnormalities. It is transmitted by an X-linked recessive gene or rarely an autosomal recessive gene. Therefore it is only males who fully express the condition. It is caused by mutations within the ED1 gene, which encodes a protein, ectodysplasin-A (EDA). Typically there is frontal bossing, saddle nose, pointed chin, a prominent supraorbital ridge with periorbital hyperpigmentation, and absence of teeth. Those affected show great intolerance to heat. In the current absence of effective treatment for many hereditary skin diseases, comprehensive, accurate prenatal or postnatal genetic counseling can provide information to parents at risk of having affected children. We report HED in a 6-year-old boy with an Ala349Thr (GCA --> ACA) missense mutation developed de novo. Both parents and a 16-week gestational age fetus were healthy. We thought direct sequencing analysis for the ED1 gene using peripheral blood or amniotic fluid was preferable for an accurate diagnosis of this disease, although there was some risk of not detecting the mutation. After the results of this study were communicated to the parents, the mother was freed of her guilty feelings of the past 6 years and has now delivered a healthy male infant.     

X性连锁少汗性外胚叶发育不良一家系EDA基因突变检测

目的:检测1例X性连锁少汗性外胚叶发育不良患儿及其家族成员EDA基因的突变情况。方法:调查患儿家系,提取家系中患儿和正常人血液基因组DNA,设计引物扩增EDA基因的外显子及其侧翼区域,并对其产物进行测序后与100例健康对照者的测序结果进行比对。结果:患儿EDA基因发生编码区第466位核苷酸由胞嘧啶变为胸腺嘧啶(c.466C>T),该突变导致第156位氨基酸由精氨酸变为半胱氨酸(p.Arg156Cys),为错义突变。先证者母亲同一位置碱基呈C～T杂峰,患儿父亲和健康对照者未检测到突变。结论:错义突变c.466C>T是导致该X性连锁少汗性外胚叶发育不良家系临床表型的主要原因。     

Functional studies for a dominant mutation in the EDAR gene responsible for hypohidrotic ectodermal dysplasia

Hypohidrotic ectodermal dysplasia (HED) is a rare genetic disorder characterized by hypotrichosis, hypohidrosis and hypodontia. The disease shows X‐linked recessive, autosomal dominant or autosomal recessive inheritance traits. The X‐linked form of HED is caused by mutations in the EDA gene, while autosomal forms result from mutations in either EDAR or EDARADD genes. Regarding recessive mutations in the EDAR gene, the pathomechanisms have been well characterized. However, it has remained largely unknown how dominant mutations in the EDAR cause HED. In this study, we performed in vitro analyses for a dominant EDAR gene mutation, p.F398*, as a representative. We showed that the p.F398* mutant EDAR completely lost its affinity to EDARADD, and suppressed the downstream nuclear factor‐κB activation induced by wild‐type EDAR in a dominant‐negative manner. Furthermore, we demonstrated that the mutant EDAR was capable of binding with the wild‐type EDAR, which led to reduced interaction between the wild‐type EDAR and EDARADD. Our findings not only underscore an essential role of the interaction between EDAR and EDARADD in ectodermal development, but also disclose, in part, the molecular basis of autosomal dominant HED.     

A novel EDA gene mutation in a Spanish family with X-linked hypohidrotic ectodermal dysplasia

X-linked hypohidrotic ectodermal dysplasia (XLHED) is characterized by abnormal development of the hair, teeth, and sweat glands. It is caused by mutations in the EDA gene, which maps to the X chromosome and encodes a protein called ectodysplasin-A, a member of the tumor necrosis factor-related ligand family. Affected males typically exhibit all the typical features of HED, but heterozygous carriers may show mild to moderate clinical manifestations. We describe the case of a Spanish family in which a novel heterozygous c.733_734insGA mutation at the EDA gene was identified. It was located in exon 5 and consisted of a frame-shift mutation at codon 245, which gave rise to an abnormal protein with a premature stop codon after 35 residues. Genetic analyses in families with XLHED are useful for checking carrier status, but they also provide information for genetic counseling and prenatal diagnosis.     

A novel frameshift mutation of the EDA1 gene in a Chinese Han family with X-linked hypohidrotic ectodermal dysplasia

Hypohidrotic ectodermal dysplasia (HED) is a rare skin disease characterized by hypotrichosis, hypodontia and hypohidrosis. HED can be autosomal dominant, autosomal recessive or X-linked. However, X-linked HED (XLHED; OMIM 305100) is the most common form. Mutations within the EDA1 gene, which encodes ectodysplasin-A, are responsible for XLHED. In this study, we investigated the EDA1 gene in a Chinese Han family with XLHED, and found a novel 1-bp deletion mutation (c.952delG) in exon 9 of the EDA1 gene, which results in a frameshift and premature termination codon. This result suggests that the c.952delG mutation of the EDA1 gene is likely to be the disease-causing mutation for XLHED in this family. Our study adds new data to the worldwide knowledge of the molecular basis of XLHED.     

A novel 4-bp insertion mutation in EDA1 gene in a Pakistani family with X-linked hypohidrotic ectodermal dysplasia

Hypohidrotic ectodermal dysplasia (HED) is a genetic disorder characterized by the absence or hypoplasia of hair, teeth, and eccrine sweat glands. The inheritance pattern of HED may be X-linked or autosomal (dominant or recessive). Mutations in the EDA 1 gene cause X-linked HED and mutations in either EDAR or EDARADD genes cause autosomal forms of HED. To search for a mutation in human EDA1 gene in a large Pakistani family demonstrating X-linked form of HED (XLHED), eight exons and splice junction sites of EDA1 gene were amplified by PCR from genomic DNA and sequenced directly in an ABI Prism 310 automated DNA sequencer. A novel four bases insertion mutation (913_914insTATA) was identified in exon 8 of the EDA 1 gene. This insertion introduces a reading frameshift leading to downstream premature termination codon in the same exon. In the present study a novel insertion mutation in EDA1 gene in a Pakistani family with XLHED has been reported. This extends our knowledge of mutations in EDA1 gene that define the pathogenic basis of HED.     

Skin fragility and hypohidrotic ectodermal dysplasia resulting from ablation of plakophilin 1

We report a 2-year-old boy with an unusual autosomal recessively inherited skin disease comprising trauma-induced skin fragility and congenital ectodermal dysplasia affecting hair, nails and sweat glands. Skin biopsy showed widening of intercellular spaces between keratinocytes and ultrastructural findings of small, poorly formed desmosomes with reduced connections to the keratin filament cytoskeleton. Immunohistochemical analysis revealed a complete absence of staining for the accessory desmosomal plaque protein plakophilin 1 (PKP1; band 6 protein). The affected individual was a compound heterozygote for null mutations on both alleles of the PKP1 gene. Both mutations occurred within the amino terminus of PKP1, the domain which normally binds the cytoskeletal keratin filament network to the cell membrane. Apart from its localization within desmosomal plaques, PKP1 may also be present within the cytoplasm and nucleus and has putative roles in signal transduction and regulation of gene activity. The clinicopathological observations in this patient demonstrate the relevance of PKP1 to desmosome formation, cutaneous cell-cell adhesion and epidermal development and demonstrate the specific manifestations of human functional knockout mutations in this gene.     

Novel mutations in the EDAR gene in two Pakistani consanguineous families with autosomal recessive hypohidrotic ectodermal dysplasia

BACKGROUND: Hypohidrotic ectodermal dysplasia (HED) is a human heritable disorder characterized by sparse hair, a lack of sweat glands and malformation of teeth. There are X-linked, autosomal recessive and autosomal dominant forms of this disorder. Mutations in the EDA gene cause X-linked HED and mutations in either the EDAR or the EDARADD genes cause autosomal forms of HED. OBJECTIVES: To identify pathogenic mutations in two consanguineous Pakistani families (A and B) with 11 affected individuals demonstrating the autosomal recessive form of HED. METHODS: Genotyping of 17 members of the two families, including eight affected and nine unaffected individuals, was carried out by using polymorphic markers D2S293, D2S1893 and D2S1891, which are closely linked to the EDAR gene on chromosome 2q11-q13. To screen for mutations in the EDAR gene, all of its exons and splice junctions were polymerase chain reaction amplified from genomic DNA and sequenced directly in an ABI Prism 310 automated sequencer. RESULTS: Genotyping results showed linkage in both the Pakistani families to the EDAR locus. Sequence analysis of the EDAR gene identified two novel mutations in the families: a missense mutation (G382S) in family A and a 4-bp deletion (718delAAAG) in family B. CONCLUSIONS: We describe novel mutations in the EDAR gene in two Pakistani families affected with the autosomal recessive form of HED. Our findings extend the body of evidence that supports the importance of the ectodysplasin A1 isoform receptor, a member of the tumour necrosis factor receptor family, in the development of ectodermal appendages.     

Hair and sweat glands in families with hypohidrotic ectodermal dysplasia: further characterization

OBJECTIVES: To gather and compare clinical and histologic information from individuals affected by hypohidrotic ectodermal dysplasia (HED) and unaffected control subjects and to assess the value of these data in the diagnosis of HED. DESIGN: Volunteer subjects attending the 20th Annual Family Conference of the National Foundation for Ectodermal Dysplasia answered a questionnaire and performed a starch-iodide sweat-function test. A subset of the subjects also donated samples of hair and 4-mm punch biopsy specimens of palmar and scalp skin. Specimens from each of these tests were assessed in a blinded fashion. Analysis was performed comparing affected and control subjects for each of the following parameters: quantification of eccrine structures in the skin biopsy specimens, analysis of hair sample trichograms for hair shaft defects, and qualitative classification of starch-iodide palm-print sweat-function test results. SETTING: An international conference for families and individuals with ectodermal dysplasias. SUBJECTS: A total of 40 subjects were included in the final analysis: 15 unaffected control subjects and 25 subjects with HED. Nine affected subjects and 9 unaffected subjects donated skin biopsy specimens. MAIN OUTCOME MEASURE: This study was designed to assess the value of 4 simple tests in supporting the diagnosis of HED. RESULTS: Investigators were blinded to group during analysis of the test samples. Trichogram examination identified 3 hair shaft abnormalities, with a slightly higher prevalence in the affected group: variable shaft thickness, trichorrhexis nodosa, and pili torti. The sensitivity and specificity for each of these findings was less than 40%. Starch-iodide paper palm imprints identified a higher likelihood of diminished or absent sweat in the affected group, but this test had a low sensitivity (44%) and an imperfect specificity (93%). Examination of horizontally sectioned skin biopsy specimens from the palm were devoid of eccrine structures in a minority of affected subjects (sensitivity, 30%; specificity, 100%). In contrast, scalp biopsy specimens lacked eccrine structures in the majority of affected subjects (sensitivity, 67%; specificity, 100%). Separate analysis excluding the subjects without apparent eccrine apparatus yielded comparable numbers of eccrine ducts from control and affected groups. CONCLUSIONS: We have defined the value of simple, easily performed tests in the morphological diagnosis of HED. Noninvasive trichogram and sweat testing results can support the diagnosis of HED, but they are not sensitive or highly specific; horizontally sectioned 4-mm punch biopsy specimens of the scalp or palms that lack eccrine structures are diagnostic of HED; scalp biopsy is much more sensitive than palmar biopsy; and a scalp biopsy specimen with detectable eccrine structures suggests that a patient does not have HED.     

Molecular genetic analysis of consanguineous Pakistani families with autosomal recessive hypohidrotic ectodermal dysplasia

Hypohidrotic ectodermal dysplasia is an inherited disorder characterized by defective development of teeth, hairs and sweat glands. X-linked hypohidrotic ectodermal dysplasia is caused by mutations in the EDA gene, and autosomal forms of hypohidrotic ectodermal dysplasia are caused by mutations in either the EDAR or the EDARADD genes. To study the molecular genetic cause of autosomal recessive hypohidrotic ectodermal dysplasia in three consanguineous Pakistani families (A, B and C), genotyping of 13 individuals was carried out by using polymorphic microsatellite markers that are closely linked to the EDAR gene on chromosome 2q11-q13 and the EDARADD gene on chromosome 1q42.2-q43. The results revealed linkage in the three families to the EDAR locus. Sequence analysis of the coding exons and splice junctions of the EDAR gene revealed two mutations: a novel non-sense mutation (p.E124X) in the probands of families A and B and a missense mutation (p.G382S) in the proband of family C. In addition, two synonymous single-nucleotide polymorphisms were also identified. The finding of mutations in Pakistani families extends the body of evidence that supports the importance of EDAR for the development of hypohidrotic ectodermal dysplasia.     

A novel 7-bp deletion mutation in a Taiwanese family with X-linked hypohidrotic ectodermal dysplasia

Hypohidrotic ectodermal dysplasia (HED) is found worldwide with an estimated incidence of 1 per 100,000 births. X-linked hypohidrotic ectodermal dysplasia (XLHED, OMIM 305100) is the most common form of the ectodermal dysplasias (ED), a rare group of hereditary diseases characterized by abnormal development of eccrine sweat glands, hair, and teeth. Heterozygous carriers of XLHED often manifest minor or moderate degrees of hypotrichosis, hypodontia, and hypohidrosis. ED1, the gene for XLHED encodes ectodysplasin A, which is a new member of the tumour necrosis factor family. The majority of mutations in XLHED are missense mutations, but one-fifth are insertion/deletions. Here we report a novel 7-bp deletion mutation (nt1242-1248) in exon 9 of the ED1 gene that results in a frameshift and premature stop codon (PTC + 38 amino acids). Mutation analysis in families with XLHED allows for genetic counselling, prenatal diagnosis and confirmation of carrier status.     

A novel 22-bp deletion mutation in a Chinese family with X-linked hypohidrotic ectodermal dysplasia

X-linked hypohidrotic ectodermal dysplasia (XLHED) is the most common form of the ectodermal dysplasias characterized by an abnormal development of eccrine sweat glands, hair and teeth. Pathogenic mutations in the ED1 gene have been identified. In this family, a 22-bp deletion mutation of exon 8 in the ED1 gene was found in the affected members but not in the healthy individuals and 100 unrelated controls. We add new variant to the knowledge of ED1 mutations in XLHED.