The characterization of hypodontia,hypohidrosis, and hypotrichosis associated with X‐linked hypohidrotic ectodermal dysplasia: A systematic review

The objective of this study was to review the published literature on X‐linked hypohidrotic ectodermal dysplasia (XLHED) for the prevalence and characteristics of three features of XLHED: hypodontia, hypohidrosis, and hypotrichosis. A systematic search of English‐language articles was conducted in May 2019 to identify publications with information on any of the three features of XLHED. We excluded studies with five or fewer participants, that did not specify X‐linked inheritance or an EDA mutation, and discussed only management of features. The weighted means for total missing teeth, location of missing teeth, prevalence of reduced and absent sweating ability, and sparse or absent hair were analyzed across all studies. Additional findings for hypodontia, hypohidrosis, and hypotrichosis were summarized qualitatively. Twenty publications (18 studies) were accepted. Reported findings for males tended to be more informative than for carrier females. The weighted mean for missing teeth for affected males was 22.4 (range: 10–28) and carrier females was 3.4 (range: 0–22). The most common conserved teeth for males were the canines. The most common missing teeth for females were the maxillary lateral incisors. The weighted mean prevalence of reduced or absent sweating ability was 95.7% for males and 71.6% for females. The weighted mean prevalence for hypotrichosis was 88.1% for males and 61.6% for females. This systematic review provides insight into the prevalence, characteristics, and variability of the three classic features of XLHED. These findings provide detailed natural history information for families with XLHED as well as key characteristics that can aid in diagnosis.     

X‐linked and autosomal recessive Hypohidrotic Ectodermal Dysplasia: genotypic‐dental phenotypic findings

Clauss F, Chassaing N, Smahi A, Vincent MC, Calvas P, Molla M, Lesot H, Alembik Y, Hadj‐Rabia S, Bodemer C, Manière MC, Schmittbuhl M. X‐linked and autosomal recessive Hypohidrotic Ectodermal Dysplasia: genotypic‐dental phenotypic findings. Hypohidrotic ectodermal dysplasia (HED) is characterized by abnormal development of ectodermal structures and its molecular etiology corresponds to mutations of EDA‐EDAR genes. The aim of this study was first to investigate the genotype and dental phenotype associated with HED and second, to explore possible correlations between dental features and molecular defects. A total of 27 patients from 24 unrelated families exhibiting clinical signs of HED (22 XLHED males, 5 autosomal recessive forms) were retrospectively included. In the sample, 25 different mutations on EDA and EDAR genes were detected; 10 were not previously described. EDA and EDAR mutations corresponded respectively to 80.0% and 20.0% of the mutations. The dental phenotype analysis revealed a mean number of primary and permanent missing teeth ranging respectively from 14.5 (4–20) to 22.5 (10–28); the majority of the patients exhibited dysmorphic teeth. Overall, no differential expression in the degree of oligodontia according to either the mutated gene, the mutated functional sub‐domains, or the mutation type, could be observed. Nevertheless, the furin group exhibited severe phenotypes unobserved in the TNF group. Significant differences in the number of some primary missing teeth (incisor and canine) related to EDA‐EDAR genes defects were detected for the first time between XLHED and autosomal recessive HED, suggesting differential local effects of EDA‐EDAR genes during odontogenesis. The present genotypic‐phenotypic findings may add to the knowledge of the consequences of the molecular dysfunction of EDA‐NF‐k B in odontogenesis, and could be helpful in genetic counseling to distinguish autosomal forms from other HED syndromes.     

ED1基因新突变导致无汗型外胚层发育不良

目的鉴定一个无汗型外胚层发育不良(HED)家系ED1基因的突变及探讨基因型与表型之间的关系,为该病的诊断,产前诊断及遗传咨询提供实验依据。方法对一个HED家系进行调查,临床资料收集及采集外周血,抽取基因组DNA;设计ED1基因外显子引物,行先证者DNA PCR扩增及序列测定,发现候选变异后对先证者的父母及120名匹配正常人进行突变位点序列分析;推导的该基因氨基酸序列(突变位点)用Clustal W软件进行多物种对比。结果先证者发现ED1基因c.158T>G(p.Leu53Arg)纯合突变,母亲为c.158T>G(p.Leu53Arg)杂合突变;先证者父亲及120例正常对照的序列分析结果未检测出相应位置突变。讨论 ED1基因突变检测是直接诊断HED有效手段之一,发现的c.158T>G(p.Leu53Arg)为新致病突变。     

X-连锁无汗性外胚层发育不良一家系EDA新发突变

目的检测一X连锁无汗性外胚层发育不良家系EDA基因突变。方法提取先证者、其姐和父母外周血基因组DNA,PCR扩增EDA基因编码区的8个外显子,PCR产物测序,明确突变位点。结果先证者EDA基因6号外显子第781位胞嘧啶C突变成胸腺嘌呤T,使其编码的蛋白第261位谷氨酰胺密码子CAA变成终止密码子UAA,蛋白表达提前终止;患者的姐姐和母亲在该位点均为C/T杂合子,患者父亲在该位点为C纯合子。结论本家系中c.781C>T突变为国内外首报,是导致X连锁无汗性外胚层发育不良临床表型的原因。     

两个X连锁少汗性外胚层发育不良家系的基因突变分析

目的 对两个X连锁隐性遗传少汗性外胚层发育不良(X-linked hypohidrotic ectodermal dysplasia,XLHED)家系进行ED1基因突变分析,为罹患家庭提供遗传咨询及产前诊断.方法 综合应用序列分析及多重连接依赖性探针扩增方法,对两个家系的先证者进行ED1基因突变分析,并针对检测到的突变位点对女性成员进行检测.采集家系1胎儿的羊水细胞进行产前诊断,包括致病突变位点的分析、ED1基因内4个短串联重复序列(short tandem repeat,STR)位点的单倍型连锁分析、性别鉴定及核型分析.结果 家系1先证者缺失ED1基因第1外显子及下游2个STR位点DXS8269,DXS1422区域,其余外显子序列分析未见异常,其女儿为该缺失突变的携带者;结合连锁分析、性别鉴定及核型分析结果,家系1胎儿为男性非ED1基因缺失突变携带者,胎儿足月分娩后随访,为健康个体.家系2先证者经序列分析检测到ED1基因第3外显子c.463C＞T(R155C)错义突变,母亲为c.463C＞T(R155C)杂合突变携带者.结论 ED1基因第1外显子区域缺失和错义突变R155C是导致2个少汗性外胚层发育不全家系患者临床表型的主要原因,ED1基因的突变检测结合单倍型分析,能准确地对该类家系提供产前诊断.     

X‐chromosomal inactivation directly influences the phenotypic manifestation of X‐linked protoporphyria

X‐linked protoporphyria (XLP), a rare erythropoietic porphyria, results from terminal exon gain‐of‐function mutations in the ALAS2 gene causing increased ALAS2 activity and markedly increased erythrocyte protoporphyrin levels. Patients present with severe cutaneous photosensitivity and may develop liver dysfunction. XLP was originally reported as X‐linked dominant with 100% penetrance in males and females. We characterized 11 heterozygous females from six unrelated XLP families and show markedly varying phenotypic and biochemical heterogeneity, reflecting the degree of X‐chromsomal inactivation of the mutant gene. ALAS2 sequencing identified the specific mutation and confirmed heterozygosity among the females. Clinical history, plasma and erythrocyte protoporphyrin levels were determined. Methylation assays of the androgen receptor and zinc‐finger MYM type 3 short tandem repeat polymorphisms estimated each heterozygotes X‐chromosomal inactivation pattern. Heterozygotes with equal or increased skewing, favoring expression of the wild‐type allele had no clinical symptoms and only slightly increased erythrocyte protoporphyrin concentrations and/or frequency of protoporphyrin‐containing peripheral blood fluorocytes. When the wild‐type allele was preferentially inactivated, heterozygous females manifested the disease phenotype and had both higher erythrocyte protoporphyrin levels and circulating fluorocytes. These findings confirm that the previous dominant classification of XLP is inappropriate and genetically misleading, as the disorder is more appropriately designated XLP.     

X-linked hypohidrotic ectodermal dysplasia and t(X;12) in a female

A female patient with features of hypohidrotic ectodermal dysplasia (HED) was found to be a carrier of a de novo t(X;12) with a breakpoint in Xq13.1. This is the second instance of an X/autosome translocation, with apparently the same X breakpoint, reported in HED.     

六个少汗性外胚层发育不全家系ED1基因的突变分析

目的 对6个少汗性外胚层发育不全(hypohidrotic ectodermal dysplasia,HED)家系进行ED1基因突变分析,为其提供遗传咨询和产前诊断.方法 采用聚合酶链反应和DNA直接测序对6个家系的先证者及其成员ED1基因的8个外显子进行序列分析.结果 6个家系患者中均检出了ED1基因突变,分别为R153C、A349T、G299S、A349T、X392Q和第9外显子缺失突变,其中R153C、X392Q和第9外显子缺失突变在中国人群中首次报告.上述位点的杂合突变在部分女性亲属中检出.结论 错义突变R153C、A349T、G299S和X392Q和第9外显子缺失是导致6个少汗性外胚层发育不全家系患者临床表型的主要原因,通过对家系个体ED1基因分析可进行携带者筛查和产前诊断.     

Mutations in EDAR account for one-quarter of non-ED1-related hypohidrotic ectodermal dysplasia

Hypohidrotic ectodermal dysplasia (HED) is characterized by abnormal development of the eccrine sweat glands, hair, and teeth. The X-linked form of the disease, caused by mutations in the ED1 gene, represents the majority of HED cases. Autosomal-dominant and -recessive forms occur occasionally and result from mutations in at least two genes: EDAR and EDARADD. These different forms are phenotypically indistinguishable. To better assess the implication of the EDAR gene in HED, we screened for mutations in 37 unrelated HED families or sporadic cases with no detected mutations in the ED1 gene. We identified 11 different mutations, nine of which are novel variants, in two familial and seven sporadic cases. Seven of the 11 are recessive mutations (c.140G>A (p.Cys47Tyr), c.266G>A (p.Arg89His), c.329A>C (p.Asp110Ala), c.442T>C (p.Cys148Arg), c.1208C>T (p.Thr403Met), c.1302G>T (p.Trp434Cys) and c.528+1G>A), and the other four are probably dominant (c.1129C>T (p.Leu377Phe), c.1237A>C (p.Thr413Pro), c.1253T>C (p.Ile418Thr), and c.1259G>A (p.Arg420Gln)). Our study demonstrates that EDAR is implicated in about 25% of non-ED1 HED, and may account for both autosomal-dominant and -recessive forms. The correlation between the nature and location of EDAR mutations and their mode of inheritance is discussed. A genotype-phenotype relationship was evaluated, since such data could be helpful for genetic counseling.     

Xq13.1缺失致少汗性外胚层发育不良的表型及遗传学分析

目的:探讨1例Xq13.1缺失致 EDA基因部分缺失的少汗性外胚层发育不良的临床表型及遗传学特点。 方法:分析1例少汗性外胚层发育不良患儿的临床资料,并进行染色体核型、家系全外显子组测序(trio-whole exome sequencing, trio-WES)、基因组拷贝数变异检查(copy ...     

Loss of the SEDL gene product (Sedlin) causes X‐linked spondyloepiphyseal dysplasia tarda: Identification of a molecular defect in a Japanese family

A 23‐year‐old man was diagnosed as having X‐linked spondyloepiphyseal dysplasia tarda (SEDT; MIM 313400) based on his disproportionately short trunk, short stature, characteristic radiological features of the spine (posterior hump, end plate sclerosis, and disc space narrowing) and the hips (short and thick femoral necks), and positive family history. This Japanese family was found to have an intragenic deletion flanking intron 2 and exon 3 of the SEDL gene that not only included the 5′ untranslated region but also the coding sequence for the first methionine through the 25th alanine. This mutation was present in the proband and his unaffected mother (a heterozygote), but not in an unaffected sister and an unaffected uncle. The nature of the mutation predicted that the SEDL protein (Sedlin) was not produced in the proband, indicating that loss of Sedlin caused SEDT. © 2001 Wiley‐Liss, Inc.     

A novel de novo frame-shift mutation of the EDA gene in a Chinese Han family with hypohidrotic ectodermal dysplasia

Hypohidrotic ectodermal dysplasia (HED) is characterized by severe hypohidrosis, hypotrichosis, and hypodontia. It can be inherited in autosomal dominant, autosomal recessive, or X-linked patterns. Mutations in the EDA gene, which encodes ectodysplasin-A, are responsible for X-linked HED (XLHED). In the present study, we identified a Chinese Han family with XLHED. Direct DNA sequence analysis of the entire coding region and exon–intron boundaries of EDA identified a novel de novo mutation, c.573_574insT, in two affected males and one carrier female. Restriction fragment length polymorphism (RFLP) analysis showed that the mutation was not present in 200 controls. The 1-bp insertion mutation resulted in a frameshift, which causes premature termination of EDA polypeptide and truncation of the EDA protein. These results suggest that the c.573_574insT mutation of the EDA gene is a cause for XLHED in the family. To the best of our knowledge, this is the first de novo insertion mutation of EDA described for XLHED.Changzheng Huang and Qinbo Yang contribute equally to this work.     

A novel missense mutation (402C → T) in exon 1 in the EDA gene in a family with X-linked hypohidrotic ectodermal dysplasia

Hypohidrotic ectodermal dysplasia (EDA), or Christ-Siemens-Touraine syndrome, is clinically characterized by hypohidrosis, hypoodontia and hypotrichosis. The X-linked form of the disease has been mapped to Xq12-q13.1, and a gene from this region has recently been cloned. This gene encodes a predicted transmembrane protein of 135 amino acids, which was found to be expressed in keratinocytes, hair follicles, and sweat glands. A variety of rearrangements in this gene have been found in patients with hypohidrotic ectodermal dysplasia.
We have screened the probands from nine unrelated Danish families with hypohidrotic ectodermal dysplasia for mutation in exon 1 of the EDA-gene by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP). In one large kindred we identified a novel missense mutation (402C → T), which changes a histidine to tyrosine at position 54 in the protein. This mutation cosegregates with the disease in the family and is the first mutation described which affects the predicted transmembrane, hydrophobic domain of the protein.     

Maternal germinal mosaicism of X‐linked agammaglobulinemia

X‐linked agammaglobulinemia (XLA) is an immunodeficiency caused by abnormalities in tyrosine kinase (BTK), and is characterized by a deficiency of peripheral blood B cells. We studied cytoplasmic expression of BTK protein and analyzed the BTK gene (BTK) in peripheral blood mononuclear cells from two siblings with XLA and additional family members. Cytoplasmic expression of BTK protein in monocytes was not detected in either patient with XLA. A single base deletion (C563) in BTK‐exon 6, which encodes the TH domain, was identified in both XLA patients. However, normal cytoplasmic expression of BTK protein in monocytes was detected in their mother without any BTK mutation. These results strongly suggest germinal mosaicism in the mother. © 2001 Wiley‐Liss. Inc.     

Carrier identification by FISH analysis in isolated cases of X‐linked ichthyosis

X‐linked ichthyosis (XLI) is an inborn error of metabolism due to steroid sulfatase (STS) deficiency. STS assay and FISH are useful in diagnosing carrier status of XLI. Biochemical analysis appears to indicate that most sporadic cases are inherited. Since this method does not seem to be completely reliable in recognizing XLI‐carriers, the aim of the present study was to corroborate by FISH whether or not most sporadic cases of XLI had de novo mutations. XLI patients were classified through STS assay and PCR amplification of 5′‐3′ ends of the STS gene. XLI patients had undetectable levels of STS activity and complete deletion of the STS gene. Patients' mothers were studied through STS assay and FISH. Nine out of 12 mothers presented an STS activity compatible with XLI‐carrier state. These mothers also had only one copy of the STS gene, indicating that they carry the primary gene defect. One mother had normal STS activity but only one copy of the STS gene. This data corroborated that most sporadic cases do not represent de novo mutations, and that FISH must be included in the analysis of mothers of sporadic cases when they present with normal STS activity, in order to correctly diagnose the XLI carrier state. © 2001 Wiley‐Liss, Inc.     

Expression of X-linked hypohidrotic ectodermal dysplasia in six males and in their mothers

Six male patients with confirmed X-linked hypohidrotic ectodermal dysplasia and their mothers were studied to determine the variation of expressivity in patients and heterozygotes, major problems of the patients, and to find a clue to pathogenesis. The number of teeth, conic in shape, in patients varied from none to 14. In addition to hypohidrosis and hypotrichosis, dry skin, reduced salivation, hoarseness and hypoplasia of the nipples were common signs. Five patients had frequent respiratory infections. The mothers lacked more than four permanent teeth, one mother had hypodontia in the deciduous dentition. The sweat pore counts were low in patients, and lower than normal in the mothers. All patients carried beta-hemolytic streptococci, four of them group A either in nose or pharynx, without symptoms. Immunoglobulin values, including IgA were normal in serum and saliva. Unexpectedly, serum parathyroid hormone concentrations both in patients and mothers were low. The major problem of the families was the risk of hyperpyrexia due to hypohidrosis, but the patients' concern was mostly because of their facial appearance.     

WNT10A gene is the second molecular candidate in a cohort of young Italian subjects with ectodermal derivative impairment (EDI)

Ectodermal dysplasias are a group of genetic disorders defined by ectodermal derivative impairment (EDI). To test the impact of the Wnt/beta‐catenin pathway in the genetic screening of EDI, we performed a molecular gene study of WNT10A in 60 subjects from a population of 133 young Italian patients referred for the impairment of at least one major ectodermal‐derived structure and who had a previous negative molecular screen for ectodysplasin signaling pathway genes ED1, EDAR, and EDARADD. Fourteen WNT10A mutations were identified in 33 subjects (24.8%), 11 of which were novel variants. The phenotype was evaluated through a detailed clinical examination of the major and minor ectodermal‐derived structures. This study is the first to show that, after ED1, WNT10A is the second molecular candidate for EDI in a large Italian Caucasian population. The study confirmed that Phe228Ile is the most frequent WNT10A variant in Caucasian populations, and that WNT10A mutations are associated with large variability in EDI.