KDF1, encoding keratinocyte differentiation factor 1, is mutated in a multigenerational family with ectodermal dysplasia

Genetic and phenotypic heterogeneity of tooth agenesis: An update including candidate genes

OBJECTIVE

This study aims to further investigate the genetic etiology as well as the corresponding characteristics of tooth agenesis (TA). It focuses on expanding the gene spectrum and exploring genotype-phenotype correlations and potential candidate genes for TA.

DESIGN

The narrative review approach was conducted, providing a comprehensive perspective of tooth agenesis-related literature.

RESULTS

We describe the (candidate) causal genes of syndromic TA and nonsyndromic TA respectively. There is overlap between the gene spectrum of the two forms. Tooth phenotypes (either the number of missing teeth or the malformations) of syndromic form are more severe than that of nonsyndromic form. The phenomenon even exists among family members carried the same variant, highlighting the disorder's complexity and the causal genes' expression variability. Besides, the candidate genes, corresponding functional and case evidence are updated, which contributes to improve the diagnosis of TA.

CONCLUSIONS

TA is a group of complex disorder regulated by multiple genetic signaling pathways. We review the previously known and novel found genes/candidate genes related to TA, emphasizing the genetic and phenotypic heterogeneity. The enlarged spectrum is useful for further promoting the understanding of TA and early diagnosis. It is suggested that molecular diagnosis is particularly vital for early management and genetic counseling.

Keratinocyte differentiation factor 1 enhances cervical cancer cell viability and migration by activating the PI3K/AKT pathway

BACKGROUND

The aim of This study is to investigate the effects of Keratinocyte differentiation factor 1 (KDF1) on cervical cancer cells and the underlying mechanisms.

METHODS

The Gene Expression Profiling Interactive Analysis database was used to analyse KDF1 expression in cervical cancer and paracancerous tissue samples. The correlation between the expression of KDF1 and clinicopathological features was also analysed. Cervical cancer cells (HeLa cells) with KDF1 overexpression or knockdown were constructed. Reverse transcription polymerase chain reaction was used to detect the mRNA expression of KDF1 in cervical cancer tissues and cells. In different treatment groups of cervical cancer cells, protein expression of KDF1, cell viability, invasion, and migration were subsequently confirmed by western blotting, CCK-8 assay, transwell assay, and wound healing assay, respectively. A PI3K inhibitor (LY294002) was used to detect the effect of KDF1 on the phosphoinositide 3-kinase (PI3K)/Protein Kinase B (AKT) pathway.

RESULTS

KDF1 was highly expressed in cervical cancer tissues and cell lines (p < 0.01), and was significantly associated with poor prognosis (p < 0.05). Knockdown of KDF1 in HeLa cells resulted in a significant decrease in cell proliferation, migration, and invasion, as well as phosphorylated PI3K (P-PI3K) and p-AKT levels (p < 0.01). However, KDF1 overexpression activated the PI3K/AKT pathway and significantly enhanced the malignant biological behaviour of cervical cancer cells (p < 0.01). Additionally, the PI3K inhibitor reduced the proliferation, invasion, and migration of HeLa cells overexpressing KDF1 (p < 0.01).

CONCLUSION

KDF1 enhances cervical cancer viability and migration by activating the PI3K/AKT pathway, and may serve as a therapeutic target for patients with cervical cancer.

KDF1 promotes ameloblast differentiation by inhibiting the IKK/IκB/NF-κB axis

Enamel protects teeth from external irritation and its formation involves sequential differentiation of ameloblasts, a dental epithelial cell. Keratinocyte differentiation factor 1 (KDF1) is important in the development of epithelial tissues and organs. However, the specific role of KDF1 in enamel formation and corresponding regulatory mechanisms are unclear. This study demonstrated that KDF1 was persistently expressed in all stages of ameloblast differentiation, through RNAscope in situ hybridization. KDF1 expression in the mouse ameloblast cell line LS8 was demonstrated via immunofluorescence assay. KDF1 was knocked out in LS8 cells using the CRISPR/Cas-9 system or overexpressed in LS8 cells through lentiviral infection. In vitro ameloblast differentiation induction, quantitative reverse transcription PCR, western blot analysis, and alkaline phosphatase (ALP) assay indicated that knockout or overexpression of KDF1 in LS8 cells decreased or increased the mRNA and protein levels of several key amelogenesis markers, as well as ALP activity. Furthermore, liquid chromatography-mass spectrometry and co-immunoprecipitation analyses revealed that KDF1 can interact with the IKK complex, thereby inhibiting the NF-κB pathway. Suppressing NF-κB activity partially recovered the decreased ameloblast differentiation in LS8 cells induced by KDF1-knockout. This study demonstrated that KDF1 can promote ameloblast differentiation of LS8 cells by inhibiting the IKK/IκB/NF-κB axis, and is a potential target for functional enamel regeneration.

Comprehensive Catalog of Variants Potentially Associated with Hidradenitis Suppurativa, Including Newly Identified Variants from a Cohort of 100 Patients

Hidradenitis suppurativa (HS) is a chronic skin disease characterized by painful, recurrent abscesses, nodules, and scarring, primarily in skin folds. The exact causes of HS are multifactorial, involving genetic, hormonal, and environmental factors. It is associated with systemic diseases such as metabolic syndrome and inflammatory bowel disease. Genetic studies have identified mutations in the γ-secretase complex that affect Notch signaling pathways critical for skin cell regulation. Despite its high heritability, most reported HS cases do not follow a simple genetic pattern. In this article, we performed whole-exome sequencing (WES) on a cohort of 100 individuals with HS, and we provide a comprehensive review of the variants known to be described or associated with HS. 91 variants were associated with the γ-secretase complex, and 78 variants were associated with other genes involved in the Notch pathway, keratinization, or immune response. Through this new genetic analysis, we have added ten new variants to the existing catalogs. All variants are available in a .vcf file and are provided as a resource for future studies.

Genome-wide association study for growth traits with 1066 individuals in largemouth bass (Micropterus salmoides)

The largemouth bass is a native species of North America that was first introduced to mainland China in the 1980s. In recent years, it has been extensively farmed in China due to its high meat quality and broad adaptability. In this study, we collected growth trait data from 1,066 largemouth bass individuals across two populations. We generated an average of approximately 7× sequencing coverage for these fish using Illumina sequencers. From the samples, we identified 2,695,687 SNPs and retained 1,809,116 SNPs for further analysis after filtering. To estimate the number of genome-wide effective SNPs, we performed LD pruning with PLINK software and identified 77,935 SNPs. Our GWAS revealed 15 SNPs associated with six growth traits. We identified a total of 24 genes related to growth, with three genes-igf1, myf5, and myf6-directly associated with skeletal muscle development and growth, located near the leading SNP on chromosome 23. Other candidate genes are involved in the development of tissues and organs or other physiological processes. These findings provide a valuable set of SNPs and genes that could be useful for genetic breeding programs aimed at enhancing growth in largemouth bass.

KDF1 Promoted Proliferation, Migration and Invasion of Lung Adenocarcinoma Cells through Activating STAT3 and AKT Pathway

KDF1 has been reported to be correlated with carcinogenesis. However, its role and mechanism are far from clear. To explore the possible role and underlying mechanism of KDF1 in lung adenocarcinoma (LUAD), we investigated KDF1 expression in LUAD tissues and the influence of KDF1 in the phenotype of LUAD cells (A549 and PC-9) as well as the underlying mechanism. Compared to non-tumor lung epithelial cells, KDF1 was upregulated in the cancer cells of the majority of LUAD patients, and its expression was correlated with tumor size. Patients with enhanced KDF1 in cancer cells (compared with paired adjacent non-neoplastic lung epithelial cells) had shorter overall survival than patients with no increased KDF1 in cancer cells. Knockdown of KDF1 inhibited the migration, proliferation and invasion of LUAD cells in vitro. And overexpression of KDF1 increased the growth of the subcutaneous tumors in mice. In terms of molecular mechanisms, overexpression of KDF1 induced the expression of AKT, p-AKT and p-STAT3. In KDF1-overexpressing A549 cells, inhibition of the STAT3 pathway decreased the level of AKT and p-AKT, whereas inhibition of the AKT pathway had no effect on the activation of STAT3. Inhibition of STAT3 or AKT pathways reversed the promoting effects of KDF1 overexpression on the LUAD cell phenotype and STAT3 inhibition appeared to have a better effect. Finally, in the cancer cells of LUAD tumor samples, the KDF1 level was observed to correlate positively with the level of p-STAT3. All these findings suggest that KDF1, which activates STAT3 and the downstream AKT pathway in LUAD, acts as a tumor-promoting factor and may represent a therapeutic target.

Functions of the RIP kinase family members in the skin

The receptor interacting protein kinases (RIPK) are a family of serine/threonine kinases that are involved in the integration of various stress signals. In response to several extracellular and/or intracellular stimuli, RIP kinases engage signaling cascades leading to the activation of NF-κB and mitogen-activated protein kinases, cell death, inflammation, differentiation and Wnt signaling and can have kinase-dependent and kinase-independent functions. Although it was previously suggested that seven RIPKs are part of the RIPK family, phylogenetic analysis indicates that there are only five genuine RIPKs. RIPK1 and RIPK3 are mainly involved in controlling and executing necroptosis in keratinocytes, while RIPK4 controls proliferation and differentiation of keratinocytes and thereby can act as a tumor suppressor in skin. Therefore, in this review we summarize and discuss the functions of RIPKs in skin homeostasis as well as the signaling pathways involved.

Gain-of-function variants in the KDF1 gene cause hidradenitis suppurativa associated with ectodermal dysplasia by stabilizing IκB kinase α

Keratinocyte differentiation factor (KDF)1 has been shown to cause ectodermal dysplasia with or without hidradenitis suppurativa in a single family. KDF1 is known to regulate epidermal differentiation through its interaction with IκB kinase (IKK)α. We report a novel de novo KDF1 variant (p.His254Tyr) in a 20-year-old male patient presenting with hidradenitis suppurativa and ectodermal dysplasia. We demonstrate that variants in KDF1 associated with hidradenitis suppurativa actually cause pathogenic gain-of-function of KDF1 through upregulation of IKKα. Ectodermal dysplasia may be present in a subset of individuals with hidradenitis suppurativa and should be investigated. Inhibition of IKKα appears to be a suitable therapeutic target for these individuals.

Dental Phenotype with Minor Ectodermal Symptoms Suggestive of WNT10A Deficiency

Ectodermal dysplasias (EDs) represent a heterogeneous group of genetic disorders characterized by the abnormal development of ectodermal-derived tissues. They include the involvement of the hair, nails, skin, sweat glands, and teeth. Pathogenic variants in EDA1 (Xq12-13.1; OMIM*300451), EDAR (2q11-q13; OMIM*604095), EDARADD (1q42-q43, OMIM*606603), and WNT10A (2q35; OMIM*606268) genes are responsible for most EDs. Bi-allelic pathogenic variants of WNT10A have been associated with autosomal recessive forms of ED, as well as non-syndromic tooth agenesis (NSTA). The potential phenotypic impact of associated modifier mutations in other ectodysplasin pathway genes has also been pointed out. We present on an 11-year-old Chinese boy with oligodontia, with conical-shaped teeth as the main phenotype, and other very mild ED signs. The genetic study identified the pathogenic variants WNT10A (NM_025216.3): c.310C > T; p. (Arg104Cys) and c.742C > T; p. (Arg248Ter) in compound heterozygosis, confirmed by parental segregation. In addition, the patient had the polymorphism EDAR (NM_022336.4): c.1109T > C, p. (Val370Ala) in homozygosis, named EDAR370. A prominent dental phenotype with minor ectodermal symptoms is very suggestive of WNT10A mutations. In this case, the EDAR370A allele might also attenuate the severity of other ED signs.

Enamel Structure Defects in Kdf1 Missense Mutation Knock-in Mice

The Keratinocyte differentiation factor 1 (KDF1) is reported to take part in tooth formation in humans, but the dental phenotype of Kdf1 mutant mice has not been understood. Additionally, the role of the KDF1 gene in dental hard tissue development is rarely known. In this study, we constructed a Kdf1 missense mutation knock-in mouse model through CRISPR/Cas9 gene-editing technology. Enamel samples from wildtypes (WT) and Kdf1 homozygous mutants (HO) were examined using micro-computed tomography (micro-CT), scanning electron microscopy (SEM), an atomic force microscope (AFM) and Raman microspectroscopy. The results showed that a novel Kdf1 missense mutation (c. 908G>C, p.R303P) knock-in mice model was constructed successfully. The enamel of HO mice incisors appeared chalky and defective, exposing the rough interior of the inner enamel and dentin. Micro-CT showed that HO mice had lower volume and mineral density in their tooth enamel. In addition, declined thickness was found in the unerupted enamel layer of incisors in the HO mice. Using SEM and AFM, it was found that enamel prisms in HO mice enamel were abnormally and variously shaped with loose decussating crystal arrangement, meanwhile the enamel rods were partially fused and collapsed, accompanied by large gaps. Furthermore, misshapen nanofibrous apatites were disorderly combined with each other. Raman microspectroscopy revealed a compromised degree of order within the crystals in the enamel after the Kdf1 mutation. To conclude, we identified enamel structure defects in the Kdf1 missense mutation knock-in mice, which displayed fragmentary appearance, abnormally shaped prism structure, decreased mineral density, altered crystal ordering degree and chemical composition of the enamel layer. This may support the potential role of the KDF1 gene in the natural development of enamel.

KDF1 Novel Variant Causes Unique Dental and Oral Epithelial Defects

Keratinocyte differentiation factor 1 (KDF1) is a recently identified and rare candidate gene for human tooth agenesis; however, KDF1-related morphological characteristics and pathological changes in dental tissue and the oral epithelium remain largely unknown. Here, we employed whole-exome sequencing (WES) and Sanger sequencing to screen for the suspected variants in a cohort of 151 tooth agenesis patients, and we segregated a novel KDF1 heterozygous missense variation, c.920G>C (p.R307P), in a non-syndromic tooth agenesis family. Essential bioinformatics analyses and tertiary structural predictions were performed to analyze the structural changes and functional impacts of the novel KDF1 variant. The subsequent functional assessment using a TOP-flash/FOP-flash luciferase reporter system demonstrated that KDF1 variants suppressed the activation of canonical Wnt signaling in 293T cells. To comprehensively investigate the KDF1-related oral morphological anomalies, we performed scanning electron microscopy and ground section of the lower right lateral deciduous incisor extracted from #285 proband, and histopathological assessment of the gingiva. The phenotypic analyses revealed a series of tooth morphological anomalies related to the KDF1 variant R307P, including a shovel-shaped lingual surface of incisors and cornicione-shaped marginal ridges with anomalous morphological occlusal grooves of premolars and molars. Notably, keratinized gingival epithelium abnormalities were revealed in the proband and characterized by epithelial dyskeratosis with residual nuclei, indistinct stratum granulosum, epithelial hyperproliferation, and impaired epithelial differentiation. Our findings revealed new developmental anomalies in the tooth and gingival epithelium of a non-syndromic tooth agenesis individual with a novel pathogenic KDF1 variant, broadening the phenotypic spectrum of KDF1-related disorders and providing new evidence for the crucial role of KDF1 in regulating human dental and oral epithelial development.

Identification of a novel missense heterozygous mutation in the KDF1 gene for non-syndromic congenital anodontia

OBJECTIVES

KDF1 is a recently identified gene related to tooth development, but it has been little studied. To date, only three cases have been reported in which KDF1 mutations are related to tooth development, including two ectodermal dysplasia cases accompanied by tooth loss and one non-syndromic case with tooth agenesis. However, no KDF1 mutations have been reported as associated with non-syndromic anodontia. Here, the aim was to investigate the genetic etiology of this condition and explore the functional role of a novel KDF1 mutation in a Chinese patient with non-syndromic anodontia.

MATERIALS AND METHODS

Pathogenic variants were identified by whole-exome and Sanger sequencing. Meanwhile, we conducted a literature review of the reported KDF1 mutations and performed an in vitro functional analysis of four anodontia-causing KDF1 mutations (one novel and three known).

RESULTS

We identified a novel de novo missense mutation (c.911 T > A, p.I304N) in the KDF1 gene in a Chinese patient with severe non-syndromic anodontia. In vitro functional studies showed altered mRNA and protein expression levels of the mutant KDF1.

CONCLUSIONS

Our results are the first report of KDF1 missense mutation causing non-syndromic anodontia.

CLINICAL RELEVANCE

This study not only further supports the important role of KDF1 in non-syndromic congenital anodontia, but also expands the spectrum of KDF1 mutations and will contribute to the genetic diagnosis and counselling of families with anodontia.

KDF1 Promoted Proliferation and Metastasis of Epithelial Ovarian Cancer via Wnt/Beta-Catenin Pathway: TCGA-Based Data Mining and Experimental Validation

Objectives: It has been reported that keratinocyte differentiation factor 1 (KDF1) was related to proliferation, differentiation, and cell cycle. However, the role of KDF1 has not been reported in ovarian cancer. The present study investigated the function and the potential mechanism of KDF1 in ovarian cancer.

Methods: We evaluated the prognostic value in ovarian cancer based on data from the Cancer Genome Atlas (TCGA) database. The Kruskal–Wallis test, Wilcoxon signed-rank test, and logistic regression were used to evaluate the relationship between KDF1 expression and clinicopathologic features. The Cox regression and the Kaplan–Meier method were adopted to evaluate prognosis-related factors. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) gene enrichment analysis, and Gene Set Enrichment Analysis (GSEA) were performed to identify the key biological process related to KDF1. Then the expression of KDF1 in ovarian cancer tissues was validated by streptavidin–peroxidase (SP) immunohistochemistry. The proliferation and invasion ability of KDF1 were determined by EdU and Transwell assay, respectively, with KDF1 gene silencing and overexpression. The mRNA expression of KDF1 was determined by qPCR. The protein expression of KDF1 was determined using the Western blot.

Methods: By performing differential expression analysis on the ovarian cancer data of the TCGA database, it was found that KDF1 is highly expressed in ovarian cancer patients and associated with poorer overall survival (OS) and progression-free survival (PFS) of ovarian cancer patients. The highly expressed KDF1 may reduce cell adhesion according to GO, KEGG, and GSEA results. After analysis combining the relevant clinical features, we found that the high expression of KDF1 is an independent prognostic factor of ovarian cancer and associated with platinum resistance and tumor metastasis in ovarian cancer. At the same time, the BioGRID database showed that there might be protein–protein interaction between KDF1 and E-cadherin. Then we further validated that the high expression of KDF1 had a close correlation with the stage and grade of ovarian cancer in ovarian cancer tissue chips. Silencing KDF1 inhibited the proliferation and invasion ability of SKOV3 cells. By contrast, ectopic expression of KDF1 promoted the proliferation and invasion ability of A2780 cells. We also found that KDF1 can interact with E-cadherin and regulate the expression of Wnt5A and β-catenin, hence activating Wnt/β-catenin pathway via in vitro and vivo experiments.

Conclusions: Based on the bioinformatics analysis, in vitro experiments, and an in vivo study, it is indicated that KDF1 played an important role in ovarian cancer progression and might be a therapeutic target for patients with ovarian cancer.

Clinical and genetic characteristics of ectodermal dysplasia in four Indian children

Introduction:

Ectodermal dysplasias (EDs) affect structures derived from the ectoderm such as skin, its appendages, nail, and teeth. In this series, we describe four patients presenting with a clinical phenotype of dysplasia of one or more ectodermal structures who underwent next-generation sequencing for mutational analysis.

Case Series:

The clinical phenotype of three patients was hypohidrotic ectodermal dysplasia (HED) and one patient was diagnosed with autoimmune polyglandular syndrome (APS) type 1. Two patients with classical clinical features of X-linked HED (XLHED) had mutations in EDA gene; variant c.924+ 8C>G (5′ proximal splice site) and c.760C>T (p.Gln254Ter). Case 3 had clinical phenotype of HED with urticaria pigmentosa, which was confirmed on skin biopsy and immunohistochemistry. This patient was found to have mutation in C1orf172; c.449G>A (p.Arg150Gln) which has not been reported previously. Case 4 was diagnosed to have APS type 1 with cutaneous features of discoloration of teeth and chronic mucocutaneous candidiasis. This patient had a compound heterozygous mutation of AIRE gene. The two variants detected were c.169C>T (p.Gln57Ter) and c.47C>T (p.Thr16Met).

Conclusion:

The present series highlights the clinic-genetic correlation in four patients with features of ED. Two variants of uncertain significance and two previously unreported variants were also found in this study.

KDF1, a Novel Tumor Suppressor in Clear Cell Renal Cell Carcinoma

KDF1 has been identified as a key regulator of epidermal proliferation and differentiation, but it is unknown whether KDF1 is involved in the pathogenesis of malignancy. No study has reported the expression and function of KDF1 in renal cancer. To explore the pathologic significance of KDF1 in clear cell renal cell carcinoma (ccRCC), the expression level of KDF1 protein in the tumor tissue of ccRCC patients was examined by immunohistochemistry and Western blot while the expression level of KDF1 mRNA was analyzed by using the data from TCGA database. In vitro cell experiments and allogeneic tumor transplantation tests were performed to determine the effects of altered KDF1 expression on the phenotype of ccRCC cells. Both the KDF1 mRNA and protein were found to be decreasingly expressed in the tumor tissue of ccRCC patients when compared with the adjacent non-tumor control tissue. The expression level of KDF1 in the tumor tissue was found to correlate negatively with the tumor grade. Patients with higher KDF1 in the tumor tissue were found to have longer overall survival and disease-specific survival time. KDF1 was shown to be an independent factor influencing the disease-specific survival of the ccRCC patients. Overexpression of KDF1 was found to inhibit the proliferation, migration and invasion of ccRCC cells, which could be reversed by decreasing the expression of KDF1 again. ccRCC cells with KDF1 overexpression were found to produce smaller transgrafted tumors. These results support the idea that KDF1 is involved in ccRCC and may function as a tumor suppressor.

MicroRNA miR-330-3p suppresses the progression of ovarian cancer by targeting RIPK4

Previous studies reported that miR-330-3p was involved in the progression of several cancers, but the potential roles of miR-330-3p in ovarian cancer (OC) were unclear. In the current study, we aimed to explore the expression pattern and functions of miR-330-3p in OC. The expression level of miR-330-3p in OC tissues and cell lines was detected using RT-qPCR. The proliferation, migration and invasion of OC cells were detected using CCK-8 assay and transwell assay, respectively. Bioinformatics analysis and luciferase reporter assay were used to analyze the targeted binding site of miR-330-3p and RIPK4. The results showed that miR-330-3p was significantly downregulated in OC tissues and cell lines. Overexpression of miR-330-3p inhibited the proliferation, migration and invasion of OC cells. Mechanistically, a dual-luciferase reported assay showed that RIPK4 is a target gene of miR-330-3p. Furthermore, rescue experiments revealed that miR-330-3p suppressed the proliferation, migration and invasion of OC cells by targeting RIPK4. In summary, our findings indicated that miR-330-3p suppressed the progression of OC by targeting RIPK4. Our results indicated that miR-330-3p/RIPK4 axis might act as a novel therapeutic target for OC treatment.

Regulation of epidermal differentiation through KDF1-mediated deubiquitination of IKKα

Progenitor cells at the basal layer of skin epidermis play an essential role in maintaining tissue homeostasis and enhancing wound repair in skin. The proliferation, differentiation, and cell death of epidermal progenitor cells have to be delicately regulated, as deregulation of this process can lead to many skin diseases, including skin cancers. However, the underlying molecular mechanisms involved in skin homeostasis remain poorly defined. In this study, with quantitative proteomics approach, we identified an important interaction between KDF1 (keratinocyte differentiation factor 1) and IKKα (IκB kinase α) in differentiating skin keratinocytes. Ablation of either KDF1 or IKKα in mice leads to similar but striking abnormalities in skin development, particularly in skin epidermal differentiation. With biochemical and mouse genetics approach, we further demonstrate that the interaction of IKKα and KDF1 is essential for epidermal differentiation. To probe deeper into the mechanisms, we find that KDF1 associates with a deubiquitinating protease USP7 (ubiquitin-specific peptidase 7), and KDF1 can regulate skin differentiation through deubiquitination and stabilization of IKKα. Taken together, our study unravels an important molecular mechanism underlying epidermal differentiation and skin tissue homeostasis.

Confirming the recessive inheritance of PERP-related erythrokeratoderma

Erythrokeratoderma (EK) is heterogeneous clinical entity characterized by excessive scaling with resulting erythrokeratotic plaques. Several genes have been linked to EK and they encode a number of proteins that are important for the integrity of the keratinocyte layer of the epidermis. PERP is a transcription factor that is activated by both p53 and p63. However, its deficiency in a mouse model appears to only recapitulate p63-mediated role in skin development and organization. We report an extended multiplex consanguineous family in which an EK phenotype with a striking similarity to that observed in Perp^-/- mice, is mapped to an autozygous region on chromosome 6 that spans PERP. Whole-exome sequencing revealed a novel variant in PERP that fully segregated with the phenotype. Functional analysis of patient- and control-derived keratinocytes revealed a deleterious effect of the identified variant on the intracellular localization of PERP. A previous report showed that PERP mutation causes a dominant form of keratoderma but a single patient in that report with a homozygous variant in PERP suggests that recessive inheritance is also possible. Our results, therefore, support the establishment of an autosomal recessive PERP-related EK phenotype in humans.

KDF1 is a novel candidate gene of non-syndromic tooth agenesis

OBJECTIVE

Tooth agenesis (TA) is featured by congenital loss of teeth, and can be divided into two subtypes, non-syndromic TA (NSTA) and syndromic TA (STA). Although 12 candidate genes of NSTA have been revealed, the genetic basis of NSTA needs to be further studied. We noticed an overlap of candidate genes between NSTA and STA, and hypothesized that some candidate genes of STA may be new candidate genes of NSTA.

METHODS

Sanger sequencing, whole exome sequencing, bioinformatics analyses and immunohistochemical staining were performed to reveal the genetic basis of the patients in a family with NSTA.

RESULTS

No pathogenic mutation was found in the 12 candidate genes of NSTA. We screened the variants of 76 STA candidate genes and identified a novel pathogenic mutation c.G908C (p.R303 P) in Keratinocyte Differentiation Factor 1 (KDF1). This mutation was cosegregated with the disease in the family. Bioinformatics analyses predicted the mutation to be pathogenic. Immunohistochemical staining of kdf1 in developing tooth germs indicated that kdf1 expression is important for the development of teeth.

CONCLUSIONS

This study identified KDF1 as a novel candidate gene for NSTA. STA candidate genes may be a promising source of new NSTA genes.

Molecular and cytoskeletal regulations in epidermal development

At the surface of the body, the epidermis covers great depth in its developmental regulation. While many genes have been shown to be important for skin development through their associations with disease phenotypes in mice and human, it is in the past decade that the intricate interplay between various molecules become gradually revealed through sophisticated genetic models and imaging analyses. In particular, there is increasing evidence suggesting that cytoskeleton-associated proteins, including adhesion proteins and the crosslinker proteins may play critical roles in regulating epidermis development. We here provide a broad overview of the various molecules involved in epidermal development with special emphasis on the cytoskeletal components.