Fitness maps to a large-effect locus in introduced stickleback populations.

Mutations of small effect underlie most adaptation to new environments, but beneficial variants with large fitness effects are expected to contribute under certain conditions. Genes and genomic regions having large effects on phenotypic differences between populations are known from numerous taxa, but fitness effect sizes have rarely been estimated. We mapped fitness over a generation in an F2 intercross between a marine and a lake stickleback population introduced to a freshwater pond. A quantitative trait locus map of the number of surviving offspring per F2 female detected a single, large-effect locus near Ectodysplasin (Eda), a gene having an ancient freshwater allele causing reduced bony armor and other changes. F2 females homozygous for the freshwater allele had twice the number of surviving offspring as homozygotes for the marine allele, producing a large selection coefficient, s = 0.50 ± 0.09 SE. Correspondingly, the frequency of the freshwater allele increased from 0.50 in F2 mothers to 0.58 in surviving offspring. We compare these results to allele frequency changes at the Eda gene in an Alaskan lake population colonized by marine stickleback in the 1980s. The frequency of the freshwater Eda allele rose steadily over multiple generations and reached 95% within 20 y, yielding a similar estimate of selection, s = 0.49 ± 0.05, but a different degree of dominance. These findings are consistent with other studies suggesting strong selection on this gene (and/or linked genes) in fresh water. Selection on ancient genetic variants carried by colonizing ancestors is likely to increase the prevalence of large-effect fitness variants in adaptive evolution.

Ancestral role of TNF-R pathway in cell differentiation in the basal metazoan Hydra.

Tumour necrosis factor receptors (TNF-Rs) and their ligands, tumour necrosis factors, are highly conserved proteins described in all metazoan phyla. They function as inducers of extrinsic apoptotic signalling and facilitate inflammation, differentiation and cell survival. TNF-Rs use distinct adaptor molecules to activate signalling cascades. Fas-associated protein with death domain (FADD) family adaptors often mediate apoptosis, and TNF-R-associated factor (TRAF) family adaptors mediate cell differentiation and inflammation. Most of these pathway components are conserved in cnidarians, and, here, we investigated the Hydra TNF-R. We report that it is related to the ectodysplasin receptor, which is involved in epithelial cell differentiation in mammals. In Hydra, it is localised in epithelial cells with incorporated nematocytes in tentacles and body column, indicating a similar function. Further experiments suggest that it interacts with the Hydra homologue of a TRAF adaptor, but not with FADD proteins. Hydra FADD proteins colocalised with Hydra caspases in death effector filaments and recruited caspases, suggesting that they are part of an apoptotic signalling pathway. Regulating epithelial cell differentiation via TRAF adaptors therefore seems to be an ancient function of TNF-Rs, whereas FADD-caspase interactions may be part of a separate apoptotic pathway.

Ectodysplasin-A mRNA in exosomes released from activated hepatic stellate cells stimulates macrophage response.

INTRODUCTION: The interaction between activated hepatic stellate cells (aHSCs) and macrophages is central to liver fibrosis development. The cargo contained within aHSC exosomes (aHSC-EXOs) and how aHSC-EXOs affect macrophage function is poorly understood. METHODS: RNA from aHSC-EXOs was separated into small (<200-basepairs) and large (≥200-basepairs) RNA species, transfected into macrophages, and macrophage IL-6 and TNFα mRNA expression and protein secretion measured. Next generation sequencing was performed on EXOs from rat quiescent and aHSCs and human aHSCs. aHSCs were transfected with siRNA against ectodysplasin-A (EDA), EXOs collected, and their effect on macrophage function analyzed. Human cirrhotic liver was analyzed for EDA mRNA expression and compared to non-tumor liver (NTL). RESULTS: Transfection with large RNA from aHSC-EXOs stimulated macrophage IL-6 and TNFα mRNA expression and protein secretion. EDA mRNA was highly expressed in aHSCs and transfection of aHSCs with EDA-siRNA decreased aHSC-EXO EDA mRNA and blunted the effect of aHSC-EXOs on macrophage function (IL-6/TNFα expression and macrophage migration). Human cirrhotic liver exhibited high EDA mRNA compared to NTL. CONCLUSIONS: HSC activation leads to altered EXO mRNA/miRNA profiles with aHSC-EXOs mRNAs exerting a dominant role in altering macrophage function. Ectodysplasin-A mRNA is an important component in aHSC-EXOs in regulating macrophage function.

A Causal Treatment for X-Linked Hypohidrotic Ectodermal Dysplasia: Long-Term Results of Short-Term Perinatal Ectodysplasin A1 Replacement.

X-linked hypohidrotic ectodermal dysplasia (XLHED), caused by a genetic deficiency of ectodysplasin A1 (EDA1), is a rare developmental disorder of ectodermal derivatives such as hair, sweat glands, and teeth. The absence of sweat glands and perspiration can evoke life-threatening hyperthermia. As molecular genetic findings are not always conclusive, the concentrations of circulating EDA1 may help to distinguish between total and partial EDA1 deficiencies. We previously treated nine male patients with obvious signs of XLHED with a recombinant EDA1 replacement protein, Fc-EDA, either shortly after birth (n = 3) or by prenatal administration in gestational week 26 and beyond (n = 6). Here, we present the long-term follow-up for up to six years. In patients who had received Fc-EDA after birth, neither sweat glands nor sweating ability were detected at the age of 12-60 months. In contrast, prenatal EDA1 replacement resulted in ample sweat gland development and pilocarpine-inducible sweating in all treated subjects, who also attained more permanent teeth than their untreated affected relatives. Normal perspiration has persisted for six years in the two oldest boys treated repeatedly with Fc-EDA in utero. When they had a sauna, adequate thermoregulation was evidenced. Lower sweat production after single prenatal dosing may indicate a dose-response relationship. The absence of circulating EDA1 in five prenatally treated subjects proved that these children would have been unable to perspire if they had been left untreated. The sixth infant was shown to produce an EDA1 molecule that, albeit interacting with its cognate receptor, cannot activate EDA1 signaling. In conclusion, a causal treatment of XLHED before birth is feasible.

Ectodysplasin-A signaling is a key integrator in the lacrimal gland-cornea feedback loop.

A lack of ectodysplasin-A (Eda) signaling leads to dry eye symptoms, which have so far only been associated with altered Meibomian glands. Here, we used loss-of-function (Eda-/-) mutant mice to unravel the impact of Eda signaling on lacrimal gland formation, maturation and subsequent physiological function. Our study demonstrates that Eda activity is dispensable during lacrimal gland embryonic development. However, using a transcriptomic approach, we show that the Eda pathway is necessary for proper cell terminal differentiation in lacrimal gland epithelium and correlated with modified expression of secreted factors commonly found in the tear film. Finally, we discovered that lacrimal glands present a bilateral reduction of Eda signaling activity in response to unilateral corneal injury. This observation hints towards a role for the Eda pathway in controlling the switch from basal to reflex tears, to support corneal wound healing. Collectively, our data suggest a crucial implication of Eda signaling in the cornea-lacrimal gland feedback loop, both in physiological and pathophysiological conditions. Our findings demonstrate that Eda downstream targets could help alleviate dry eye symptoms.

Prenatal ultrasound findings of ectodermal dysplasia: a case report.

BACKGROUND: Ectodermal Dysplasia is a diverse group of inherited disorders characterized by a congenital defect in two or more ectodermal structures. Due to a fairly low incidence, to the best of our knowledge there are few clues that can assist in making an effective prenatal ultrasound diagnosis. Currently, the prenatal diagnosis of ectodermal dysplasia depends on a fetal genetic test combined with the family history. In this case report, we present a fetal case of ectodermal dysplasia with a remarkable prenatal ultrasound image, genetic testing, family history, and relevant exams of the stillbirth. CASE PRESENTATION: A multipara with a 22-week singleton male pregnancy undergoing a fetal ultrasound examination. The image showed a hypoplastic maxilla and mandible. Subsequently, the ectodermal dysplasia was defined using a family history and genetic testing. The skin pathology from the aborted fetus demonstrated a hypohidrotic type. The computed tomography (CT) reconstruction after induced labor confirmed the prenatal ultrasound findings of the maxilla and mandible. CONCLUSIONS: This case suggested that prenatal ultrasound may provide a valuable clue of ectodermal dysplasia. The diagnosis can be established using further prenatal genetic testing and a family history.

The Role of Ectodysplasin A on the Ocular Surface Homeostasis.

Ectodysplasin A (EDA), a ligand of the TNF family, plays an important role in maintaining the homeostasis of the ocular surface. EDA is necessary for the development of the meibomian gland, the lacrimal gland, as well as the proliferation and barrier function of the corneal epithelium. The mutation of EDA can induce the destruction of the ocular surface resulting in keratopathy, abnormality of the meibomian gland and maturation of the lacrimal gland. Experimental animal studies showed that a prenatal ultrasound-guided intra-amniotic injection or postnatal intravenous administration of soluble recombinant EDA protein can efficiently prevent the development of ocular surface abnormalities in EDA mutant animals. Furthermore, local application of EDA could restore the damaged ocular surface to some extent. Hence, a recombinant EDA-based therapy may serve as a novel paradigm to treat ocular surface disorders, such as meibomian gland dysfunction and corneal epithelium abnormalities.

Ectodysplasin A1 Deficiency Leads to Osteopetrosis-like Changes in Bones of the Skull Associated with Diminished Osteoclastic Activity.

Pathogenic variants of the gene Eda cause X-linked hypohidrotic ectodermal dysplasia (XLHED), which is characterized by structural abnormalities or lack of ectodermal appendages. Signs of dysplasia are not restricted to derivatives of the ectodermal layer, but mesodermal abnormalities, such as craniofacial dysmorphism, are also frequently observed, suggesting close reciprocal interactions between the ectoderm and mesoderm; however, a causal link has remained unsubstantiated. We investigated the functional impact of defective ectodysplasin A1 (Eda1) signaling on postnatal bone homeostasis in Eda1-deficient Tabby mice. Interestingly, Eda1 was detected in wild-type mouse calvariae throughout postnatal lifetime. In calvariae, bone-lining Osterix (Osx)+ osteoblasts stained positive for Eda1, and osteoclasts were revealed as Eda receptor (Edar)-positive. Moreover, adult Eda1-deficient calvarial bone showed osteopetrosis-like changes with significantly diminished marrow space, which was maintained during adulthood. Concomitantly with osteopetrosis-like changes, Tabby calvarial bone and Tabby bone marrow-derived osteoclasts had far less osteoclastic activity-associated co-enzymes including cathepsin K, Mmp9, Trap, and Tcirg1 (V-type proton ATPase a3 subunit) compared with wild-type calvariae in vivo or osteoclasts in vitro, indicating that Eda1 deficiency may affect the activity of osteoclasts. Finally, we confirmed that nuclear Nfatc1-positive osteoclasts were strongly diminished during mature osteoclastic differentiation under M-CSF and RANKL in the Tabby model, while Fc-EDA treatment of Tabby-derived osteoclasts significantly increased nuclear translocation of Nfatc1. Furthermore, we identified enhanced Nfatc1 and NF-κB transcriptional activity following Fc-EDA treatment in vitro using luciferase assays. Overall, the results indicate that diminished expressions of osteoclastic activity-associated co-enzymes may lead to disturbed bone homeostasis in Tabby calvariae postnatally.

Differences in developmental potential predict the contrasting patterns of dental diversification in characiform and cypriniform fishes.

Morphological diversification during adaptive radiation may depend on factors external or internal to the lineage. We provide evidence for the latter in characiform fishes (tetras and piranhas), which exhibit extensive dental diversity. Phylogenetic character mapping supported regain of lost teeth as contributing to this diversity. To test for latent potential for dentition that would facilitate its evolutionary expansion, we overexpressed a tooth initiation signal, the tumour necrosis factor pathway ligand ectodysplasin, in a model characiform, the Mexican tetra (Astyanax mexicanus). This manipulation resulted in extensive ectopic dentition, in contrast with its previously reported limited effect in the zebrafish (Danio rerio). Tooth location in the order Cypriniformes, to which the zebrafish belongs, is much more restricted than in characiforms, a pattern that may be explained by differences in the retention of ancestral developmental potential. Our results suggest that differences in evolvability between lineages may lead to contrasting patterns of diversification.

Eda-activated RelB recruits an SWI/SNF (BAF) chromatin-remodeling complex and initiates gene transcription in skin appendage formation.

Ectodysplasin A (Eda) signaling activates NF-κB during skin appendage formation, but how Eda controls specific gene transcription remains unclear. Here, we find that Eda triggers the formation of an NF-κB-associated SWI/SNF (BAF) complex in which p50/RelB recruits a linker protein, Tfg, that interacts with BAF45d in the BAF complex. We further reveal that Tfg is initially induced by Eda-mediated RelB activation and then bridges RelB and BAF for subsequent gene regulation. The BAF component BAF250a is particularly up-regulated in skin appendages, and epidermal knockout of BAF250a impairs skin appendage development, resulting in phenotypes similar to those of Eda-deficient mouse models. Transcription profiling identifies several target genes regulated by Eda, RelB, and BAF. Notably, RelB and the BAF complex are indispensable for transcription of Eda target genes, and both BAF complex and Eda signaling are required to open chromatin of Eda targets. Our studies thus suggest that Eda initiates a signaling cascade and recruits a BAF complex to specific gene loci to facilitate transcription during organogenesis.

Comparative analysis of rare EDAR mutations and tooth agenesis pattern in EDAR- and EDA-associated nonsyndromic oligodontia.

Nonsyndromic oligodontia is a rare congenital anomaly. Mutations in the ectodysplasin A receptor (EDAR) gene are the primary cause of hypohidrotic ectodermal dysplasia but are rarely reported in nonsyndromic oligodontia. This study investigated EDAR mutations in multiplex nonsyndromic oligodontia and comparatively analyzed the EDAR- and EDA-related tooth agenesis patterns. Mutation screening was carried out using whole-exome sequencing and familial segregation. Evolutionary conservation and conformational analyses were used to evaluate the potential pathogenic influence of EDAR mutants. EDAR mutations were found to occur in 10.7% of nonsyndromic oligodontia cases. We reported seven heterozygous mutations of EDAR, including five novel mutations (c.404G>A, c.871G>A, c.43G>A, c.1072C>T, and c.1109T>C) and two known mutations (c.319A>G and c.1138A>C). Genotype-phenotype correlation analysis demonstrated that the EDAR-related tooth agenesis pattern was markedly different from EDA. The mandibular second premolars were most frequently missing (57.69%) in EDAR-mutated patients. Our results provide new evidence for the genotypic study of nonsyndromic oligodontia and suggest that EDAR haploinsufficiency results in nonsyndromic tooth agenesis. Furthermore, the distinct pattern between EDAR- and EDA-related tooth agenesis can be used as a guide for mutation screening during the clinical genetic diagnosis of this genetic disorder.

Safety and immunogenicity of Fc-EDA, a recombinant ectodysplasin A1 replacement protein, in human subjects.

In X-linked hypohidrotic ectodermal dysplasia, the most frequent ectodermal dysplasia, an inherited deficiency of the signalling protein ectodysplasin A1 (EDA1) impairs the development of the skin and its appendages, various eccrine glands, and dentition. The severe hypohidrosis common to X-linked hypohidrotic ectodermal dysplasia patients may lead to life-threatening hyperthermia, especially during hot weather or febrile illness. Fc-EDA, an EDA1 replacement protein known to prevent the disease in newborn animals, was tested in 2 clinical trials (human adults and neonates) and additionally administered under compassionate use to 3 infants in utero. The data support the safety of Fc-EDA and efficacy if applied prenatally. Anti-drug antibodies were detected after intravenous administration in adult males and nonpregnant females, but not in pregnant women when Fc-EDA was delivered intra-amniotically. Most importantly, there was no detectable immune response to the investigational drug in neonates treated by intravenous infusions and in infants who had received Fc-EDA in utero. In conclusion, the safety profile of this drug encourages further development of prenatal EDA1 replacement therapy.

Novel and Private EDA Mutations and Clinical Phenotypes of Korean Patients with X-Linked Hypohidrotic Ectodermal Dysplasia.

X-linked hypohidrotic ectodermal dysplasia (XLHED; OMIM 305100) is the most common form of ectodermal dysplasia, presenting with the triad of hypotrichosis, hypodontia, and hypohidrosis. This disorder is caused by mutations in EDA, which encodes ectodysplasin A, a member of the tumor necrosis factor superfamily. In this study, we describe clinical and genetic characteristics of 10 Korean XLHED patients (9 males, 1 female) from 9 families. Nine out of the 10 patients manifested the cardinal triad of symptoms. Six patients had a positive family history, while 2 patients were brothers. The most common initial presentation was hypotrichosis or hypodontia, while 1 patient presented with recurrent high fever in early infancy. Sanger sequencing of the EDA gene was performed and revealed 9 different mutations. Three had been reported previously, and 6 were novel mutations. One female patient, carrying a previously reported missense mutation, might be affected by skewed X-inactivation. This is the first observational study investigating genetically confirmed XLHED patients in Korea. To provide appropriate supportive care and genetic counseling, clinicians should consider the possibility of XLHED in the differential diagnosis of recurrent fever in infants, as well as recognize the typical triad of symptoms.

Investigating the association between armour coverage and parasite infection in an estuarine population of stickleback.

Background: When threespine stickleback colonized fresh water, they repeatedly evolved reduced armour plating via changes in Eda allele frequency. This evolution is typically attributed to differential predation pressure between marine and freshwater environments. However, the chromosomal region containing Eda is associated with many other phenotypes, including schooling, antipredator behaviour, and immunity. Consequently, the evolution of armour plating may be driven by multiple selective pressures acting on Eda or linked genes. Question: Is parasite infection associated with armour phenotype? Hypothesis: Parasite load differs between stickleback armour plate morphs. Organisms: An armour-polymorphic population of threespine stickleback (Gasterosteus aculeatus), and their parasites. Field site: In June 2009 and 2012, we sampled stickleback from a single human-made salt-marsh pool in the Campbell River Estuary on Vancouver Island. Methods: We counted macroparasites on approximately 100 fish per year and counted lateral armour plates. We used generalized linear models to test for correlations between armour morph and parasite load. Results: Most parasite species were not associated with armour. The gill parasite Thersitina was more abundant on more fully armoured fish in both years. The nematode Eustrongylides also exhibited a marginally significant positive trend. If parasitic infections reduce stickleback fitness, this positive covariance between armour and infection would accelerate the loss of armour plating in stickleback colonizing fresh water.

Attenuation of Mammary Gland Dysplasia and Feeding Difficulties in Tabby Mice by Fetal Therapy.

Hypohidrotic ectodermal dysplasias (HED) are hereditary differentiation disorders of multiple ectodermal structures including the mammary gland. The X-linked form of HED (XLHED) is caused by a lack of the secreted signaling molecule ectodysplasin A1 (EDA1) which is encoded by the gene EDA and belongs to the tumor necrosis factor (TNF) superfamily. Although male patients (hemizygous) are usually more severely affected by XLHED, heterozygous female carriers of an EDA mutation may also suffer from a variety of symptoms, in particular from abnormal development of their breasts. In Tabby mice, a well-studied animal model of XLHED, EDA1 is absent. We investigated the effects of prenatal administration of Fc-EDA, a recombinant EDA1 replacement protein, on mammary gland development in female Tabby mice. Intra-amniotic delivery of Fc-EDA to fetal animals resulted later in improved breastfeeding and thus promoted the growth of their offspring. In detail, such treatment led to a normalization of the nipple shape (protrusion, tapering) that facilitated sucking. Mammary glands of treated female Tabby mice also showed internal changes, including enhanced branching morphogenesis and ductal elongation. Our findings indicate that EDA receptor stimulation during development has a stable impact on later stages of mammary gland differentiation, including lactation, but also show that intra-amniotic administration of an EDA1 replacement protein to fetal Tabby mice partially corrects the mammary gland phenotype in female adult animals.

Ectodysplasin A regulates epithelial barrier function through sonic hedgehog signalling pathway.

Ectodysplasin A (Eda), a member of the tumour necrosis factor superfamily, plays an important role in ectodermal organ development. An EDA mutation underlies the most common of ectodermal dysplasias, that is X-linked hypohidrotic ectodermal dysplasia (XLHED) in humans. Even though it lacks a developmental function, the role of Eda during the postnatal stage remains elusive. In this study, we found tight junctional proteins ZO-1 and claudin-1 expression is largely reduced in epidermal, corneal and lung epithelia in Eda mutant Tabby mice at different postnatal ages. These declines are associated with tail ulceration, corneal pannus formation and lung infection. Furthermore, topical application of recombinant Eda protein markedly mitigated corneal barrier dysfunction. Using cultures of a human corneal epithelial cell line and Tabby mouse skin tissue explants, Eda up-regulated expression of ZO-1 and claudin-1 through activation of the sonic hedgehog signalling pathway. We conclude that EDA gene expression contributes to the maintenance of epithelial barrier function. Such insight may help efforts to identify novel strategies for improving management of XLHED disease manifestations in a clinical setting.

Ectodysplasin A protein promotes corneal epithelial cell proliferation.

The EDA gene encodes ectodysplasin A (Eda), which if mutated causes X-linked hypohidrotic ectodermal dysplasia (XLHED) disease in humans. Ocular surface changes occur in XLHED patients whereas its underlying mechanism remains elusive. In this study, we found Eda was highly expressed in meibomian glands, and it was detected in human tears but not serum. Corneal epithelial integrity was defective and the thickness was reduced in the early postnatal stage of Eda mutant Tabby mice. Corneal epithelial cell proliferation decreased and the epithelial wound healing was delayed in Tabby mice, whereas it was restored by exogenous Eda. Eda exposure promoted mouse corneal epithelial wound healing during organ culture, whereas scratch wound assay showed that it did not affect human corneal epithelial cell line migration. Epidermal growth factor receptor (EGFR), phosphorylated EGFR (p-EGFR), and phosphorylated ERK1/2 (p-ERK) were down-regulated in Tabby mice corneal epithelium. Eda treatment up-regulated the expression of Ki67, EGFR, p-EGFR, and p-ERK in human corneal epithelial cells in a dose-dependent manner. In conclusion, Eda protein can be secreted from meibomian glands and promotes corneal epithelial cell proliferation through regulation of the EGFR signaling pathway. Eda release into the tears plays an essential role in the maintenance of corneal epithelial homeostasis.

Ongoing niche differentiation under high gene flow in a polymorphic brackish water threespine stickleback (Gasterosteus aculeatus) population.

BACKGROUND: Marine threespine sticklebacks colonized and adapted to brackish and freshwater environments since the last Pleistocene glacial. Throughout the Holarctic, three lateral plate morphs are observed; the low, partial and completely plated morph. We test if the three plate morphs in the brackish water Lake Engervann, Norway, differ in body size, trophic morphology (gill raker number and length), niche (stable isotopes; δ15N, δ13C, and parasites (Theristina gasterostei, Trematoda spp.)), genetic structure (microsatellites) and the lateral-plate encoding Stn382 (Ectodysplasin) gene. We examine differences temporally (autumn 2006/spring 2007) and spatially (upper/lower sections of the lake - reflecting low versus high salinity). RESULTS: All morphs belonged to one gene pool. The complete morph was larger than the low plated, with the partial morph intermediate. The number of lateral plates ranged 8-71, with means of 64.2 for complete, 40.3 for partial, and 14.9 for low plated morph. Stickleback δ15N was higher in the lower lake section, while δ13C was higher in the upper section. Stickleback isotopic values were greater in autumn. The low plated morph had larger variances in δ15N and δ13C than the other morphs. Sticklebacks in the upper section had more T. gasterostei than in the lower section which had more Trematoda spp. Sticklebacks had less T. gasterostei, but more Trematoda spp. in autumn than spring. Sticklebacks with few and short rakers had more T. gasterostei, while sticklebacks with longer rakers had more Trematoda. spp. Stickleback with higher δ15N values had more T. gasterostei, while sticklebacks with higher δ15N and δ13C values had more Trematoda spp. The low plated morph had fewer Trematoda spp. than other morphs. CONCLUSIONS: Trait-ecology associations may imply that the three lateral plate morphs in the brackish water lagoon of Lake Engervann are experiencing ongoing divergent selection for niche and migratory life history strategies under high gene flow. As such, the brackish water zone may generally act as a generator of genomic diversity to be selected upon in the different environments where threespine sticklebacks can live.

Conservation analysis and pathogenicity prediction of mutant genes of ectodysplasin a.

BACKGROUND: Hypohidrotic ectodermal dysplasia (HED) is a common recessive X-linked hereditary disease that affects the development of ectoderm. Gene mutations of ectodysplasin A (EDA) play key roles in process of this disease. In our preliminary study, three unknown mutation sites (c.878 T > G, c.663-697del and c.587-615del) were detected from the pedigrees of HED. METHODS: Conservation analysis of the related homologous proteins in 3 unknown EDA gene mutation sites was conducted using the University of California Santa Cruz (UCSC) Genome Browser database. SIFT and PolyPhen-2, the online gene function prediction software, were utilized to predict the pathogenicity of point mutation of c.878 T > G. RESULTS: All three unknown mutation sites were located in the highly-conserved region of EDA and possessed strong amino acid conservation among different species. In addition, the results of the pathogenicity prediction of point mutation of c.878 T > G by SIFT (P = 0.00) and PolyPhen-2 (S = 0.997) demonstrated that the mutation site had considerable pathogenicity theoretically. CONCLUSIONS: The EDA mutations of c.878 T > G, c.663-697del and c.587-615del may be responsible for the pathogenesis of HED in their pedigrees.

A novel splicing mutation of ectodysplasin A gene responsible for hypohidrotic ectodermal dysplasia.

Hypohidrotic ectodermal dysplasia (HED) is characterized by hypohidrosis, hypodontia, sparse hair, and characteristic facial features. This condition is caused by an ectodysplasin A (EDA) gene mutation. In this study, we examined two HED pedigrees and investigated the molecular genetics of the defect. Direct sequencing analysis revealed a previously unidentified mutation in the EDA splice donor site (c.526 + 1G>A). The function of the mutant EDA gene was predicted through online investigations and subsequently confirmed by splicing analysis in vitro. The mutation resulted in the production of a truncated EDA-A1 protein caused by complete omission of exon 3. This novel functional skipping-splicing EDA mutation was considered to be the cause of HED in the two pedigrees reported here. Our findings, combined with those reported elsewhere, provide an improved understanding of the pathogenic mechanism of HED as well as important information for a genetic diagnosis.