Novel CDH3 mutations in hypotrichosis with juvenile macular dystrophy

The first reported case of CDH3-related hypotrichosis with juvenile macular dystrophy from Jordan: a case report

BACKGROUND

Pathogenic variants in the Cadherin 3 (CDH3) gene are responsible for the occurrence of Hypotrichosis with Juvenile Macular Dystrophy (HJMD) and Ectodermal Dysplasia, Ectrodactyly and Macular Dystrophy Syndrome (EEMS), both of which are rare autosomal recessive disorders characterized by hypotrichosis and progressive macular dystrophy. The CDH3 gene encodes for P-cadherin, a calcium-binding protein that is essential for cell-cell adhesion, which is expressed in the retinal pigment epithelial cells and hair follicles.

MATERIALS AND METHODS

Fundus examination of both eyes was done in addition to clinical investigation. Genomic DNA was extracted from a whole-blood sample and whole-exome sequencing (WES) was performed to identify the underlying etiology.All identified variants were evaluated for their pathogenicity and causality.

RESULTS

We present the first case of HJMD in a 23-year-old female patient from Jordan. The patient presented to our ophthalmology clinic with poor vision in both eyes. Gross examination revealed sparse scalp hair along with macular dystrophy on fundus exam in both eyes. HJMD was suspected and whole-exome sequencing (WES) confirmed the diagnosis with the identification of a homozygous frameshift deletion (p.Gly277AlafsTer20) localised in exon 7 of the CDH3 gene.

CONCLUSION

Blindness due to progressive macular degeneration is a common manifestation in numerous syndromic recessive disorders such as HJMD. Ophthalmologists should consider the importance of systemic manifestations and genetic testing for the confirmation of diagnosis.

Multimodal imaging of Hypotrichosis with juvenile macular dystrophy: a case report

BACKGROUND

To report the first Italian case of hypotrichosis with juvenile macular dystrophy complicated by macular neovascularization diagnosed through multimodal imaging.

CASE PRESENTATION

An 11-year-old boy was referred to our Institution for bilateral maculopathy of unknown origin. Multimodal imaging helps the diagnosis of Juvenile Macular Dystrophy with Hypotrichosis (HJMD). Fundus examination showed several alterations of the retinal pigment epithelium and circular pigmented area of chorioretinal atrophy. Structural spectral domain optical coherence tomography (OCT) showed some backscattering phenomenon with several alterations of retinal pigment epithelium and photoreceptor layer in both eyes. Moreover, OCT showed hyperreflective lesion beneath the neuroepithelium in left eye. OCT angiography (OCT-A) revealed a pathologic neovascular network in choriocapillaris plexus, probably the result of a fibrovascular membrane. Multifocal electroretinograms (MfERGs) showed functional alterations in 12.22° of the central retina. In order to confirm the suspicion of HJMD, the child and both parents underwent genetic testing. Both parents resulted to be heterozygous healthy carriers of a single variation.

CONCLUSION

Multimodal imaging, in particular OCT-A, is a useful aid, along to clinical findings and genetics, for the diagnosis of inherited retinal dystrophies.

The first Japanese family of CDH3-related hypotrichosis with juvenile macular dystrophy

BACKGROUND

Hypotrichosis with juvenile macular dystrophy (HJMD) is a rare autosomal recessive inherited disorder caused by biallelic variants in the CDH3 gene encoding P-cadherin. Here, we report two Japanese sibling patients with HJMD.

METHODS

Whole-exome sequencing (WES) was performed to identify disease-causing variants. In addition, ophthalmic and dermatological examinations were performed to classify the phenotype of each patient.

RESULTS

The WES analysis revealed novel compound heterozygous CDH3 variants [c.123_129dupAGGCGCG (p.Glu44fsX26) and c.2280+1G>T] in both patients; the unaffected, nonconsanguineous parents each exhibited one of the variants. Both patients showed the same clinical findings. Ophthalmologically, they exhibited progressive loss of visual acuity and chorioretinal macular atrophy, as examined with fundoscopy, fundus autofluorescence imaging, and optical coherence tomography. Full-field electroretinography, assessing generalized retinal function, revealed nearly normal amplitudes of both rod- and cone-mediated responses. Multifocal electroretinography, reflecting macular function, showed extremely decreased responses in the central area, corresponding to the chorioretinal atrophy. Dermatological examination revealed diffuse thinning of the scalp hair, which was sparse and fragile.

CONCLUSION

This is the first report of Japanese patients with HJMD and novel compound heterozygous truncating variants in CDH3. Our findings can expand the knowledge and understanding of CDH3-related HJMD, which could be helpful to ophthalmologists and dermatologists.

Hypotrichosis with Juvenile Macular Dystrophy in Saudi Arabia: A Case Report

Hypotrichosis with juvenile macular dystrophy is an autosomal recessive disorder due to a mutation in the CDH3 gene. As its name indicates, the disease classically presented with hypotrichosis and early visual impairment. We describe herein a family member with alopecia since birth associated with severe visual impairment in their early life. We suspect the diagnosis of hypotrichosis with juvenile macular dystrophy. Genetic testing confirms the clinical suspension. We emphasize the importance of genetic testing for proper genetic counseling.

Correlating Adaptive Optics Images to Clinical Findings in Juvenile Macular Dystrophy with Hypotrichosis in Siblings with Homozygous CDH3 Pathogenic Variation

OBJECTIVE

We report on two German siblings diagnosed with congenital hypotrichosis and juvenile macular dystrophy, an extremely rare syndrome affecting both hair growth and visual functions.

METHODS

A detailed ophthalmological examination was carried out including fundus examination, visual acuity assessment, visual field determination, color vision testing, and electrophysiology (electroretinography [ERG]). Additionally, fundus photography and autofluorescence imaging (FAF) was performed, along with optical coherence tomography (OCT) and adaptive optics (AO) fundus imaging. Targeted Sanger sequencing and next-generation gene panel sequencing were carried out.

RESULTS

Macular dystrophy was evident in the fundus of both patients, as was a central scotoma in the static visual field. The kinetic visual field was normal. The ERG recordings were also normal, but the amplitudes of the multifocal ERG were reduced in the central 4-5° of the retina. The FAF images revealed a large central hypofluorescent area surrounded by a hyperfluorescent ring. The OCT images showed atrophy in the outer layers and tubulations. The AO images depicted a loss of central photoreceptors, as well as severe central atrophy in patient 1. A cone mosaic was observable in the peripheral AO fundus images of both patients. The disrupted cone mosaic on the AO images correlated with the hypofluorescent areas on autofluorescence. DNA testing identified the homozygous, likely pathogenic variant c.1508G>A/p.(Arg503His) (chr16:68719191) in the CDH3 gene.

CONCLUSIONS

The two siblings revealed hypotrichosis and macular dystrophy in both eyes. The identification of a homozygous CDH3 mutation in each patient confirms the syndromic entity of hypotrichosis with juvenile macular degeneration.

Hypotrichosis with juvenile macular dystrophy: Combination of whole-genome sequencing and genome-wide homozygosity mapping identifies a large deletion in CDH3 initially undetected by whole-exome sequencing-A lesson from next-generation sequencing

BACKGROUND

Hypotrichosis with juvenile macular dystrophy (HJMD) is an autosomal recessive disorder characterized by abnormal growth of scalp hair and juvenile macular degeneration leading to blindness. We have explored the genetic basis of HJMD in a large consanguineous family with 12 affected patients, 1-76 years of age, with characteristic phenotypes.

METHODS

We first applied genome-wide homozygosity mapping to 10 affected individuals for linkage analysis to identify the genomic region of the defective gene. All affected individuals shared a 7.2 Mb region of homozygosity on chromosome 16q21-22.3, which harbored 298 genes, including CDH3, previously associated with HJMD. However, whole-exome sequencing (WES) failed to identify the causative mutation in CDH3.

RESULTS

Further investigation revealed a missense variant in a gene closely linked to CDH3 (1.4 Mb distance: FHOD1: c.1306A>G, p.Arg436Gly). This variant was homozygous in all affected individuals and heterozygous in 18 out of 19 obligate carriers. While this variant was found by bioinformatics predictions to be likely pathogenic, a knock-in mouse for this variant, made by the CRISPR/Cas, showed no disease phenotype. However, using whole-genome sequencing (WGS), we were able to identify a novel Alu recombination-mediated deletion in CDH3:c.del161-811_246 + 1,044.

CONCLUSION

WGS was able to identify a deep intronic deletion mutation, not detected by WES.

Genetic Hair Disorders: A Review

Hair loss in early childhood represents a broad differential diagnosis which can be a diagnostic and therapeutic challenge for a physician. It is important to consider the diagnosis of a genetic hair disorder. Genetic hair disorders are a large group of inherited disorders, many of which are rare. Genetic hair abnormalities in children can be an isolated phenomenon or part of genetic syndromes. Hair changes may be a significant finding or even the initial presentation of a syndrome giving a clue to the diagnosis, such as Netherton syndrome and trichothiodystrophy. Detailed history including family history and physical examination of hair and other ectodermal structures such as nails, sweat glands, and sebaceous glands with the use of dermoscopic devices and biopsy all provide important clues to establish the correct diagnosis. Understanding the pathophysiology of genetic hair defects will allow for better comprehension of their treatment and prognosis. For example, in patients with an isolated hair defect, the main problem is aesthetic. In contrast, when the hair defect is associated with a syndrome, the prognosis will depend mainly on the associated condition. Treatment of many genetic hair disorders is focused on treating the primary cause and minimizing trauma to the hair.

CDH3 gene related hypotrichosis and juvenile macular dystrophy - A case with a novel mutation

Purpose

CDH3-related hypotrichosis with juvenile macular dystrophy (HJMD) is an autosomal-recessive entity characterized by congenital sparse scalp hair and macular dystrophy, leading to severe central visual loss. We report a family with HJMD caused by a novel CDH3 gene mutation and review the mutation spectrum in HJMD. A detailed phenotypic assessment for patients whose molecular results were reported previously is also summarized.

Observations

We present a 13-year-old Turkish girl who experienced gradual bilateral visual deterioration with marked hair loss. Hair-pull test results and scalp skin texture were normal. The eyebrows and eyelashes were normal, and no abnormality in the teeth, nails, or limbs was detected. Fundus examination revealed bilateral ring-shaped atrophy of the retinal pigment epithelium with patchy intraretinal pigment clumping at the posterior pole. DNA sequencing analysis detected a novel homozygous deletion (c.447_467del (p.149_156del)) in exon 5 of the CDH3 gene of the patient. Both healthy parents and an older brother were heterozygous for the mutation.

Conclusions and importance

This case of HJMD was related to a novel homozygous mutation, termed c.447_467del (p.149_156del). These findings have significance for the future mutational analysis and genetic counseling of families with HJMD, particularly in our region. The presence of sparse hair in childhood, with or without limb anomalies, should alert clinicians to request an eye consultation. Pediatricians, dermatologists, and ophthalmologists should be aware of the rarely seen entity of juvenile macular dystrophy with hypotrichosis.

New CDH3 mutation in the first Spanish case of hypotrichosis with juvenile macular dystrophy, a case report

Background

CDH3 on 16q22.1 is responsible for two rare autosomal recessive disorders with hypotrichosis and progressive macular dystrophy: Hypotrichosis with Juvenile Macular Dystrophy and Ectodermal Dysplasia, Ectrodactyly and Macular Dystrophy. We present a new case of Hypotrichosis with Juvenile Macular Dystrophy.

Case presentation

A Spanish male born in 1998 from non-consanguineous healthy parents with a suspected diagnosis of Keratosis Follicularis Spinulosa Decalvans and Retinitis Pigmentosa Inversa referred to our Genetics Department (IIS-Fundación Jiménez Díaz).

Molecular study of ABCA4 was performed, and a heterozygous missense p.Val2050Leu variant in ABCA4 was found.

Clinical revision reclassified this patient as Hypotrichosis with Juvenile Macular Dystrophy. Therefore, further CDH3 sequencing was performed showing a novel maternal missense change p.Val205Met (probably pathogenic by in silico analysis), and a previously reported paternal frameshift c.830del;p.Gly277Alafs*20, thus supporting the clinical diagnosis..

Conclusions

This is not only the first Spanish case with this clinical and molecular diagnosis, but a new mutation has been described in CDH3. Moreover, this work reflects the importance of joint assessment of clinical signs and evaluation of pedigree for a correct genetic study approach and diagnostic.

Hypotrichosis and juvenile macular dystrophy caused by CDH3 mutation: A candidate disease for retinal gene therapy

Hypotrichosis with juvenile macular dystrophy (HJMD) is an autosomal recessive disorder that causes childhood visual impairment. HJMD is caused by mutations in CDH3 which encodes cadherin-3, a protein expressed in retinal pigment epithelium (RPE) cells that may have a key role in intercellular adhesion. We present a case of HJMD and analyse its phenotypic and molecular characteristics to assess the potential for retinal gene therapy as a means of preventing severe visual loss in this condition. Longitudinal in vivo imaging of the retina showed the relative anatomical preservation of the macula, which suggested the presence of a therapeutic window for gene augmentation therapy to preserve visual acuity. The coding sequence of CDH3 fits within the packaging limit of recombinant adeno-associated virus vectors that have been shown to be safe in clinical trials and can efficiently target RPE cells. This report expands the number of reported cases of HJMD and highlights the phenotypic characteristics to consider when selecting candidates for retinal gene therapy.

Phenotypic observations in "hypotrichosis with juvenile macular dystrophy" (recessive CDH3 mutations)

PURPOSE

Recessive mutations in CDH3 cause "hypotrichosis with juvenile macular dystrophy," typically recognized by the presence of prominent dermatological features. We report novel phenotypic observations and associated mutations in four patients from three families, including one who did not have frank hypotrichosis.

METHODS

Retrospective case series (2010-2014).

RESULTS

Four affected individuals from three consanguineous Arabian families were identified. All four subjects (two sisters and two unrelated males; 5, 13, 17, and 26 years old) had homozygous recessive CDH3 mutations not previously associated with the condition (c.307C>T; p.R103 in two sisters, c.1859_1862delCTCT in both unrelated males). Symptomatic visual loss was since birth or early childhood. One male subject did not have frank hypotrichosis, but review of symptoms revealed relatively slow hair growth and an inability to conceive children. None had dental or digital findings, although one female noted slow nail growth. All had a circumscribed central maculopathy with borders that did not respect posterior pole horizontal arterioles (typically extending beyond the major arcades) and associated with polygonal pigment clumping. Recognition of this pattern led us to suspect the diagnosis in the male without frank hypotrichosis. Retinal dysfunction was cone-rod (rather than macular only) by ERG in one patient, who developed severe central macular atrophy and a macular hole.

CONCLUSIONS

Ophthalmologists should consider the diagnosis of CDH3-related retinopathy in individuals with such clinical features whether or not there is frank hypotrichosis.

A case of hypotrichosis with juvenile macular dystrophy

PURPOSE

To report a very rare case of hypotrichosis with juvenile macular dystrophy.

METHODS

Clinical case report and literature review.

RESULTS

A 6-year-old boy was referred to us for a retinal evaluation after retinal defects were found bilaterally by his optometrist. His ocular symptoms included decreased visual acuity and light sensitivity. His ocular history was unremarkable. Review of systems was positive for hypotrichosis. Fundus examination revealed bull's eye maculopathy bilaterally. The patient was found to have a cadherin-3 genetic defect, which is associated with hypotrichosis with juvenile macular dystrophy. In follow-up, fundus autofluorescence revealed severe hypoautofluorescence with severe retinal pigment epithelium loss, and spectral domain optical coherence tomography showed evidence of retinal pigment epithelium, photoreceptor, and inner segment/outer segment disruption bilaterally.

CONCLUSION

Hypotrichosis with juvenile macular dystrophy is a very rare genetic disorder that should be in the differential for macular degeneration during the first 4 decades of life. A detailed review of systems should always be performed on these patients.

P-cadherin and the journey to cancer metastasis

P-cadherin is a classical cell-to-cell adhesion molecule with a homeostatic function in several normal tissues. However, its behaviour in the malignant setting is notably dependent on the cellular context. In some tumour models, such as melanoma and oral squamous cell carcinoma, P-cadherin acts as a tumour suppressor, since its absence is associated with a more aggressive cancer cell phenotype; nevertheless, the overexpression of this molecule is linked to significant tumour promoting effects in the breast, ovarian, prostate, endometrial, skin, gastric, pancreas and colon neoplasms. Herein, we review the role of P-cadherin in cancer cell invasion, as well as in loco-regional and distant metastatic dissemination. We focus in P-cadherin signalling pathways that are activated to induce invasion and metastasis, as well as cancer stem cell properties. The signalling network downstream of P-cadherin is notably dependent on the cellular and tissue context and includes the activation of integrin molecules, receptor tyrosine kinases, small molecule GTPases, EMT transcription factors, and crosstalk with other cadherin family members. As new oncogenic molecular pathways mediated by P-cadherin are uncovered, putative therapeutic options can be tested, which will allow for the targeting of invasion or metastatic disease, depending on the tumour model.

Whole Exome Sequencing Reveals Mutations in Known Retinal Disease Genes in 33 out of 68 Israeli Families with Inherited Retinopathies

Whole exome sequencing (WES) is a powerful technique for identifying sequence changes in the human genome. The goal of this study was to delineate the genetic defects in patients with inherited retinal diseases (IRDs) using WES. WES was performed on 90 patient DNA samples from 68 families and 226 known genes for IRDs were analyzed. Sanger sequencing was used to validate potential pathogenic variants that were also subjected to segregation analysis in families. Thirty-three causative mutations (19 novel and 14 known) in 25 genes were identified in 33 of the 68 families. The vast majority of mutations (30 out of 33) have not been reported in the Israeli and the Palestinian populations. Nine out of the 33 mutations were detected in additional families from the same ethnic population, suggesting a founder effect. In two families, identified phenotypes were different from the previously reported clinical findings associated with the causative gene. This is the largest genetic analysis of IRDs in the Israeli and Palestinian populations to date. We also demonstrate that WES is a powerful tool for rapid analysis of known disease genes in large patient cohorts.

The role of P-cadherin in skin biology and skin pathology: lessons from the hair follicle

Adherens junctions (AJs) are one of the major intercellular junctions in various epithelia including the epidermis and the follicular epithelium. AJs connect the cell surface to the actin cytoskeleton and comprise classic transmembrane cadherins, such as P-cadherin, armadillo family proteins, and actin microfilaments. Loss-of-function mutations in CDH3, which encodes P-cadherin, result in two allelic autosomal recessive disorders: hypotrichosis with juvenile macular dystrophy (HJMD) and ectodermal dysplasia, ectrodactyly, and macular dystrophy (EEM) syndromes. Both syndromes feature sparse hair heralding progressive macular dystrophy. EEM syndrome is characterized in addition by ectodermal and limb defects. Recent studies have demonstrated that, together with its involvement in cell-cell adhesion, P-cadherin plays a crucial role in regulating cell signaling, malignant transformation, and other major intercellular processes. Here, we review the roles of P-cadherin in skin and hair biology, with emphasize on human hair growth, cycling and pigmentation.

Cadherin defects in inherited human diseases

The tight control of cell-cell connectivity mediated by cadherins is a key issue in human health and disease. The human genome contains over 115 genes encoding cadherins and cadherin-like proteins. Defects in about 21 of these proteins (8 classical, 5 desmosomal, 8 atypical cadherins) have been linked to inherited disorders in humans, including skin and hair disorders, cardiomyopathies, sensory defects associated with deafness and blindness, and psychiatric disorders. With the advent of exome and genome sequencing techniques, we can anticipate the discovery of yet more evidence for the involvement of additional cadherins. Elucidation of the related physiopathological mechanisms underlying these conditions should help to clarify the roles played by these cadherins in tissues and the ways in which defects in different cadherins cause such a wide spectrum of associated phenotypes. These disorders also constitute disparate model systems for investigations of the relative contributions of mechanical adhesive strength and intracellular signaling pathways to the pathogenic process for a given cadherin.

P-cadherin regulates human hair growth and cycling via canonical Wnt signaling and transforming growth factor-β2

P-cadherin is a key component of epithelial adherens junctions, and it is prominently expressed in the hair follicle (HF) matrix. Loss-of-function mutations in CDH3, which encodes P-cadherin, result in hypotrichosis with juvenile macular dystrophy (HJMD), an autosomal recessive disorder featuring sparse and short hair. Here, we attempted to recapitulate some aspects of HJMD in vitro by transfecting normal, organ-cultured human scalp HFs with lipofectamine and CDH3-specific or scrambled control siRNAs. As in HJMD patients, P-cadherin silencing inhibited hair shaft growth, prematurely induced HF regression (catagen), and inhibited hair matrix keratinocyte proliferation. In situ, membrane β-catenin expression and transcription of the β-catenin target gene, axin2, were significantly reduced, whereas glycogen synthase kinase 3 β (GSK3β) and phospho-β-catenin immunoreactivity were increased. These effects were partially reversed by inhibiting GSK3β. P-cadherin silencing reduced the expression of the anagen-promoting growth factor, IGF-1, whereas that of transforming growth factor β 2 (TGFβ2; catagen promoter) was enhanced. Neutralizing TGFβ antagonized the catagen-promoting effects of P-cadherin silencing. In summary, we introduce human HFs as an attractive preclinical model for studying the functions of P-cadherin in human epithelial biology and pathology. This model demonstrates that cadherins can be successfully knocked down in an intact human organ in vitro, and shows that P-cadherin is needed for anagen maintenance by regulating canonical Wnt signaling and suppressing TGFβ2.

CDH3-Related Syndromes: Report on a New Mutation and Overview of the Genotype-Phenotype Correlations

Hypotrichosis with juvenile macular dystrophy (HJMD) and ectodermal dysplasia, ectrodactyly and macular dystrophy (EEM) are both caused by mutations in the CDH3 gene. In this report, we describe a family with EEM syndrome caused by a novel CDH3 gene mutation and review the mutation spectrum and limb abnormalities in both EEM and HJMD. A protein structure model showing the localization of different mutations causing both syndromes is presented. The CDH3 gene was sequenced and investigation of the mutations performed using a protein structure model. The conservation score was calculated by ConSurf. We identified a novel CDH3 gene mutation, p.G277V, which resides in a conserved residue located on a β-strand in the second cadherin domain. Review of the data on previously published mutations showed intra-familial and inter-familial variations in the severity of the limb abnormalities. Syndactyly was the most consistent clinical finding present in all the patients regardless of mutation type. The results of our study point to a phenotypic continuum between HJMD and EEM. It is important for genetic counseling to keep in mind the possible clinical/phenotypic overlap between these 2 syndromes and to be aware of the possible risk of limb abnormalities in future pregnancies in families with HJMD syndrome. CDH3 gene mutation screening is recommended in patients with both these syndromes as part of the work-up in order to offer appropriate genetic counseling.

Cadherins as targets for genetic diseases

The 6-billion human population provides a vast reservoir of mutations, which, in addition to the opportunity of detecting very subtle defects, including specific cognitive dysfunctions as well as late appearing disorders, offers a unique background in which to investigate the roles of cell-cell adhesion proteins. Here we focus on inherited human disorders involving members of the cadherin superfamily. Most of the advances concern monogenic disorders. Yet, with the development of single nucleotide polymorphism (SNP) association studies, cadherin genes are emerging as susceptibility genes in multifactorial disorders. Various skin and heart disorders revealed the critical role played by desmosomal cadherins in epidermis, hairs, and myocardium, which experience high mechanical stress. Of particular interest in that respect is the study of Usher syndrome type 1 (USH1), a hereditary syndromic form of deafness. Studies of USH1 brought to light the crucial role of transient fibrous links formed by cadherin 23 and protocadherin 15 in the cohesion of the developing hair bundle, the mechanoreceptive structure of the auditory sensory cells, as well as the involvement of these cadherins in the formation of the tip-link, a key component of the mechano-electrical transduction machinery. Finally, in line with the well-established role of cadherins in synaptic formation, maintenance, strength, and plasticity, a growing number of cadherin family members, especially protocadherins, have been found to be involved in neuropsychiatric disorders.

Secreted phosphoprotein 1 upstream invasive network construction and analysis of lung adenocarcinoma compared with human normal adjacent tissues by integrative biocomputation

The aim of this study is to set up single molecular secreted phosphoprotein 1 (SPP1) upstream invasive network of lung adenocarcinoma. This paper proposed an integrated method based on linear programming and a decomposition procedure with integrated analysis of the significant function cluster using Kappa statistics and fuzzy heuristic clustering. Our study proved that only modules appearing in lung adenocarcinoma include cytokine module (CXCL13, GREM1_2 inhibition), cell adhesion module (COL11A1_2 activation; CDH3 inhibition), and receptor binding module (NMU activation; CXCL13, GREM1_2 inhibition), which increase the invasion of cancer cell. We compared skeletal development, signal, biological regulation, sequence variant modules between human normal adjacent tissues and lung adenocarcinoma. SPP1 skeletal development module appears in human normal adjacent tissues (COL11A1_1 activation; COL10A1 inhibition), whereas in lung adenocarcinoma (COL11A1_2, COL1A2 activation); signal module appears in human normal adjacent tissues (COL11A1_1, CXCL13, MMP11, SPINK1 activation; COL10A1, COL3A1 inhibition), whereas in lung adenocarcinoma (COL11A1_2, COL1A2, MMP12 activation; CDH3, CXCL13, GREM1_2, MMP11, SPINK1 inhibition); biological regulation module appears in human normal adjacent tissues (CXCL13, MKI67, PYCR1 activation; NEK2, SPDEF, TOP2A_2, TOX3_1 inhibition), whereas in lung adenocarcinoma (HMGB3, MKI67, NMU, PYCR1, TOX3_2 activation; CXCL13, SPDEF, TOP2A_2 inhibition); sequence variant module appears in human normal adjacent tissues (COL11A1_1, MKI67, MMP11 activation; ASPM, COL10A1, COL3A1, NEK2, TMPRSS4, TOP2A_2 inhibition), whereas in lung adenocarcinoma (COL11A1_2, COL1A2, HMMR, MKI67, MMP12 activation; ABCC3, ASPM, CDH3, MMP11, TOP2A_2 inhibition). It can be deduced that modules above in human normal adjacent tissues reflect the invasive inhibition of normal cells, whereas in lung adenocarcinoma increase the invasion of cancer cell. Our study of SPP1 upstream invasive network may be useful to identify novel and potentially targets for prognosis and therapy of lung adenocarcinoma.

A novel splice-acceptor site mutation in CDH3 gene in a consanguineous family exhibiting hypotrichosis with juvenile macular dystrophy

Mutations in CDH3 gene, encoding P-cadherin, are responsible for hypotrichosis with juvenile macular dystrophy (HJMD), which is a rare autosomal recessive disorder. The HJMD is characterized by congenital sparse hair on scalp and progressive severe degenerative changes of the retinal macula which leads to variable degrees of blindness. The present study reports a large consanguineous Pakistani family with six individuals affected with HJMD. Genotyping using polymorphic microsatellite markers showed linkage of the family to CDH3 gene on chromosome 16q22.1. Sequence analysis of the CDH3 gene revealed a novel splice site mutation (c.IVS10-1 G → A) in intron 10, which leads to skipping of exon 11 and probably synthesizing a non-functional premature truncated protein.

P-cadherin is a p63 target gene with a crucial role in the developing human limb bud and hair follicle

P-cadherin is a member of the classical cadherin family that forms the transmembrane core of adherens junctions. Recently, mutations in the P-cadherin gene (CDH3) have been shown to cause two inherited diseases in humans: hypotrichosis with juvenile macular dystrophy (HJMD) and ectodermal dysplasia, ectrodactyly, macular dystrophy (EEM syndrome). The common features of both diseases are sparse hair and macular dystrophy of the retina, while only EEM syndrome shows the additional finding of split hand/foot malformation (SHFM). We identified five consanguineous Pakistani families with either HJMD or EEM syndrome, and detected pathogenic mutations in the CDH3 gene of all five families. In order to define the role of P-cadherin in hair follicle and limb development, we performed expression studies on P-cadherin in the mouse embryo, and demonstrated the predominant expression of P-cadherin not only in the hair follicle placode, but also at the apical ectodermal ridge (AER) of the limb bud. Based on the evidence that mutations in the p63 gene also result in hypotrichosis and SHFM, and that the expression patterns of p63 and P-cadherin overlap in the hair follicle placode and AER, we postulated that CDH3 could be a direct transcriptional target gene of p63. We performed promoter assays and ChIP, which revealed that p63 directly interacts with two distinct regions of the CDH3 promoter. We conclude that P-cadherin is a newly defined transcriptional target gene of p63, with a crucial role in hair follicle morphogenesis as well as the AER during limb bud outgrowth in humans, whereas it is not required for either in mice.

Genetic diseases of junctions

Tight junctions, gap junctions, adherens junctions, and desmosomes represent intricate structural intercellular channels and bridges that are present in several tissues, including epidermis. Clues to the important function of these units in epithelial cell biology have been gleaned from a variety of studies including naturally occurring and engineered mutations, animal models and other in vitro experiments. In this review, we focus on mutations that have been detected in human diseases. These observations provide intriguing insight into the biological complexities of cell-cell contact and intercellular communication as well as demonstrating the spectrum of inherited human diseases that are associated with mutations in genes encoding the component proteins. Over the last decade or so, human gene mutations have been reported in four tight junction proteins (claudin 1, 14, 16, and zona occludens 2), nine gap junction proteins (connexin 26, 30, 30.3, 31, 32, 40, 43, 46, and 50), one adherens junction protein (P-cadherin) and eight components of desmosomes (plakophilin (PKP) 1 and 2, desmoplakin, plakoglobin--which is also present in adherens junctions, desmoglein (DSG) 1, 2, 4, and corneodesmosin). These discoveries have often highlighted novel or unusual phenotypes, including abnormal skin barrier function, alterations in epidermal differentiation, and developmental anomalies of various ectodermal appendages, especially hair, as well as a range of extracutaneous pathologies. However, this review focuses mainly on inherited disorders of junctions that have an abnormal skin phenotype.