Genetic Hair Disorders: A Review

Aesthetic oral rehabilitation of the upper-anterior sector with supra-nano filling resin in a patient with woolly hair syndrome: case report

BACKGROUND

Woolly Hair Syndrome (WHS) is a rare birth condition that affects the structure of hair in non-black people. The pathogenesis is not yet defined. It is postulated that the hair follicle's desmosomes (specifically desmoplaquine, placoglobin and placofilin-1, which are cell structural proteins that keep the adhesion among close cells) would be altered in this pathology, leading to fragility in the cellular union. It is subdivided into two large groups: the localized or circumscribed variant and the generalized variant. From birth or first months of life, patients with WHS are clinically characterized by the presence of a portion or entire scalp area of very short frizzy hair, usually of a smaller diameter, brittle and lighter color. The most frequent skin manifestations are pilar keratosis and palmo-plantar keratodermia. The diagnosis is based on the clinical findings, and it is facilitated by trichotoscopic examination. However, a definitive diagnosis of WHS requires genetic testing. Oral agenesis, enamel defects (such as hypomineralization), atypical caries, dental inclusion, and malformed pin-shaped teeth may occur.

OBJECTIVE

To describe an aesthetic alternative of oral rehabilitation using the mock-up technique in a patient with WHS.

CLINICAL CASE

A 5-year-old female patient diagnosed with WHS from the National Institute of Child Health NIHCH: Breña, Lima, who was referred from the Genetic service to the Pediatric Dentistry service in order to screen outbreaks of infection associated with odontogenic origin and dental anomalies. At the ectoscopy, a patient with short capillary length, brittle and curly hair, dry skin, and nail dystrophy was observed. At the intraoral clinical examination, anterior pieces of 52, 51, 61, 62, and enamel hypomineralization were observed in all teeth. The radiographic examination showed agenesis of parts 41, 34, and 45. Integral dental treatment was performed in the operating room under general anesthesia due to the complexity of the case. Pulpectomy in pieces 52, 51, 61, 62, post of composite resin, and rehabilitation with supra-nanow filling resin using the mock-up technique were proposed as alternative treatments.

CONCLUSION

The making of supra-nano filling resin-based crowns using the mock-up technique is an alternative treatment for aesthetic oral rehabilitation in deciduous dentition of patients with WHS. The aesthetic treatment was achieved using supra nano-filling resins. After 12 months of dental treatment, a favorable response was observed, improving the chewing, phonation and aesthetics of the patient.

Translational Research Techniques for the Facial Plastic Surgeon: An Overview

The field of facial plastic and reconstructive surgery (FPRS) is an incredibly diverse, multispecialty field that seeks innovative and novel solutions for the management of physical defects on the head and neck. To aid in the advancement of medical and surgical treatments for these defects, there has been a recent emphasis on the importance of translational research. With recent technological advancements, there are now a myriad of research techniques that are widely accessible for physician and scientist use in translational research. Such techniques include integrated multiomics, advanced cell culture and microfluidic tissue models, established animal models, and emerging computer models generated using bioinformatics. This study discusses these various research techniques and how they have and can be used for research in the context of various important diseases within the field of FPRS.

A novel homozygous mutation in LSS gene possibly causes hypotrichosis simplex in two siblings of a Tibetan family from the western Sichuan province of China

Aim: Hypotrichosis simplex (MIM 146520) is a rare form of monogenic hereditary alopecia. Several genes have been identified as being associated with the disease, including LPAR6, LIPH, and DSG4. LSS encoding lanosterol synthase (LSS) has been shown to cause hypotrichosis simplex, but the related mechanisms have not been elucidated to date. This study aims to find mutations in LSS from a Chinese family, among which a 21-year-old male patient and his 9-year-old sister were affected by hypotrichosis simplex. Methods: Dermoscopy and histological analysis were used to examine patients' scalps, while exome sequencing was used to find the mutations in LSS. Results: The hair loss was only detected on the scalp of the proband and his sister, while other ectodermal structures were normal with no systemic abnormalities. Further, the exome sequencing identified a new homozygous mutation NM_002340.6 (LSS_v001):c.812T>C (p.(Ile271Thr)) in the LSS gene of the proband, which was also found in his sister. In addition, a heterozygous mutation of LSS was found in their asymptomatic parents. Finally, the possible protein structure of the mutational LSS was predicted. Conclusion: The hypotrichosis simplex reported here could be an autosomal recessive disease in this family. The mutation on LSS might reduce the enzyme activity of LSS, thus leading to the disease.

Hair shaft disorders in children – An update

Disorders of hair shaft are a diverse group of congenital and acquired abnormalities of the hair that can pose a diagnostic and therapeutic challenge to the dermatologists. Hair shaft abnormalities can occur as an isolated phenomenon or can be associated with an underlying genetic syndrome. Any change in the texture, appearance, and growth of the hair should prompt evaluation of the patient for the presence of any hair shaft anomaly. The diagnosis can be suggested by a complete history and physical examination of the hair-bearing areas as well as other ectodermal structures (nails and teeth). A key feature in the evaluation of hair shaft defects is to determine the fragility of the hair shaft that can be elucidated by performing the "tug test." Trichoscopy and light microscopy serve as valuable tools in establishing the specific type of hair shaft disorder. An update of the approach for the diagnosis and management is included in this review.

A 15-Year-Old Girl with Trichorhinophalangeal Syndrome Type 1 with Non-ossifying Fibroma in Femur: A Case Report

Introduction: Trichorhinophalangeal syndrome (TRPS) is a sporadic autosomal dominant disorder with approximately 200 reported cases worldwide. We aimed to report a 15-year-old girl with TRPS type 1 (TRPS1) and the second reported case with a rare non-ossifying fibroma (NOF) in the distal part of her left femur. Case Presentation: We introduce a 15-year-old girl who presented to the outpatient rheumatology clinic at 17 Shahrivar Children's Hospital, Rasht, Iran, with the chief complaint of osteoarticular pain and bone deformities. She had sparse hair, a recession of the fronto-temporal hairline, and unusually thick eyebrows at the medial and abnormal sparseness of the lateral margins. Physical examination of the limbs revealed short fingers and toes with proximal interphalangeal (PIP) ulnar deviation of the second and third fingers in both hands. Shortness of the fourth fingers, especially in the right hand, and the swelling of the PIP joints of both hands were prominent. Genetic analysis showed deletion mutation in the TRPS1 gene in chromosome 8q24 compatible with TRPS1. Conclusions: Several symptoms and signs, including distinctive craniofacial features and ectodermal and skeletal abnormalities, are used for proper TRPS diagnosis. A correct and on-time diagnosis is essential to perform supportive care for the patient to prevent morbidities. Bone lesions, such as NOF1, can also be presented in TRPS1 patients and may be correlated with TRPS1 mutation. Further investigations are required on the association of the TRPS gene with NOF bone lesions.

Regulation and dysregulation of hair regeneration: aiming for clinical application

Hair growth and regeneration represents a remarkable example of stem cell function. Recent progress emphasizes the micro- and macro- environment that controls the regeneration process. There is a shift from a stem cell-centered view toward the various layers of regulatory mechanisms that control hair regeneration, which include local growth factors, immune and neuroendocrine signals, and dietary and environmental factors. This is better suited for clinical application in multiple forms of hair disorders: in male pattern hair loss, the stem cells are largely preserved, but androgen signaling diminishes hair growth; in alopecia areata, an immune attack is targeted toward the growing hair follicle without abrogating its regeneration capability. Genome-wide association studies further revealed the genetic bases of these disorders, although the precise pathological mechanisms of the identified loci remain largely unknown. By analyzing the dysregulation of hair regeneration under pathological conditions, we can better address the complex interactions among stem cells, the differentiated progeny, and mesenchymal components, and highlight the critical role of macroenvironment adjustment that is essential for hair growth and regeneration. The poly-genetic origin of these disorders makes the study of hair regeneration an interesting and challenging field.

Glucocorticoid signaling and regulatory T cells cooperate to maintain the hair-follicle stem-cell niche

Maintenance of tissue homeostasis is dependent on the communication between stem cells and supporting cells in the same niche. Regulatory T cells (Treg cells) are emerging as a critical component of the stem-cell niche for supporting their differentiation. How Treg cells sense dynamic signals in this microenvironment and communicate with stem cells is mostly unknown. In the present study, by using hair follicles (HFs) to study Treg cell-stem cell crosstalk, we show an unrecognized function of the steroid hormone glucocorticoid in instructing skin-resident Treg cells to facilitate HF stem-cell (HFSC) activation and HF regeneration. Ablation of the glucocorticoid receptor (GR) in Treg cells blocks hair regeneration without affecting immune homeostasis. Mechanistically, GR and Foxp3 cooperate in Treg cells to induce transforming growth factor β3 (TGF-β3), which activates Smad2/3 in HFSCs and facilitates HFSC proliferation. The present study identifies crosstalk between Treg cells and HFSCs mediated by the GR-TGF-β3 axis, highlighting a possible means of manipulating Treg cells to support tissue regeneration.

Identification of the Key Genes Associated with Different Hair Types in the Inner Mongolia Cashmere Goat

The Inner Mongolia cashmere goat is an excellent local breed in China. According to the characteristics of wool quilts, the Inner Mongolia cashmere goat can be divided into three types: a long-hair type (hair length of >22 cm), a short-hair type (hair length of ≤13 cm), and an intermediate type (hair length of >13 cm and ≤22 cm). It is found that hair length has a certain reference value for the indirect selection of other important economic traits of cashmere. In order to explore the molecular mechanisms and related regulatory genes of the different hair types, a weighted gene coexpression network analysis (WGCNA) was carried out on the gene expression data and phenotypic data of 12-month-old Inner Mongolia cashmere goats with a long-hair type (LHG) and a short-hair type (SHG) to explore the coexpression modules related to different coat types and nine candidate genes, and detect the relative expression of key candidate genes. The results showed that the WGCNA divided these genes into 19 coexpression modules and found that there was a strong correlation between one module and different hair types. The expression trends of this module’s genes were different in the two hair types, with high expression in the LHG and low expression in the SHG. GO functions are mainly concentrated in cellular components, including intermediate filaments (GO:0005882), intermediate filament cytoskeletons (GO:0045111), and cytoskeletal parts (GO:0044430). The KEGG pathway is mainly enriched in arginine as well as proline metabolism (chx00330) and the MAPK signaling pathway (chx04010). The candidate genes of the different hair types, including the KRT39, KRT74, LOC100861184, LOC102177231, LOC102178767, LOC102179881, LOC106503203, LOC108638293, and LOC108638298 genes, were screened. Through qRT-PCR, it was found that there were significant differences in these candidate genes between the two hair types, and most of them had a significant positive correlation with hair length. It was preliminarily inferred that these candidate genes could regulate the different hair types of cashmere goats and provide molecular markers for hair growth.

Independent DSG4 frameshift variants in cats with hair shaft dystrophy

Investigations of hereditary phenotypes in spontaneous mutants may help to better understand the physiological functions of the altered genes. We investigated two unrelated domestic shorthair cats with bulbous swellings of the hair shafts. The clinical, histopathological, and ultrastructural features were similar to those in mice with lanceolate hair phenotype caused by loss-of-function variants in Dsg4 encoding desmoglein 4. We sequenced the genomes from both affected cats and compared the data of each affected cat to 61 control genomes. A search for private homozygous variants in the DSG4 candidate gene revealed independent frameshift variants in each case, c.76del or p.Ile26fsLeu*4 in case no. 1 and c.1777del or p.His593Thrfs*23 in case no. 2. DSG4 is a transmembrane glycoprotein located primarily in the extracellular part of desmosomes, a complex of adhesion molecules responsible for connecting the keratin intermediate filaments of neighbouring epithelial cells. Desmosomes are essential for normal hair shaft formation. Both identified DSG4 variants in the affected cats lead to premature stop codons and truncate major parts of the open-reading frame. We assume that this leads to a complete loss of DSG4 function, resulting in an incorrect formation of the desmosomes and causing the development of defective hair shafts. Together with the knowledge on the effects of DSG4 variants in other species, our data suggest that the identified DSG4 variants cause the hair shaft dystrophy. To the best of our knowledge, this study represents the first report of pathogenic DSG4 variants in domestic animals.

Localized hair loss in infancy: a review

PURPOSE OF REVIEW

The current review will address the different causes of localized hair loss in infancy. The data presented here will provide clinicians with the latest understanding of different disorders leading to localized hair loss and will provide recommendations for further management of infants who present with alopecia.

RECENT FINDINGS

Localized hair loss in infancy is common, but its underlying causes vary greatly. Alopecia in infants can be categorized into congenital, genetic, inflammatory, mechanical, and physiologic causes. Decisions regarding further management are complex, as they often involve not only cosmetic concerns, but also work-up of possible systemic medical issues related to hair loss.

SUMMARY

Clinicians must be able to distinguish between the different causes of infantile hair loss so that appropriate work-up and further management can be pursued. Factors such as physical appearance, timing of presentation, dermoscopic exam, histopathology, and associated systemic features can help lead clinicians to the correct diagnosis in the case of an infant with localized alopecia.

Athena: Speciality Certificate Examination case for Paediatrics and Genetics - A case of brittle hair

The parents of a 1-year-old boy are concerned regarding his hair being very brittle. He is being investigated for seizures. He has significant delay in psychomotor development. He had complete lack of scalp and eyebrow hair at birth. On examination, his hair was sparse, coarse in texture and twisted. Hair microscopy demonstrated pili torti. He had a low serum ceruloplasmin and serum copper. A diagnosis of Menkes Syndrome (MS) was made.

A Nonsense Variant in Hephaestin Like 1 (HEPHL1) Is Responsible for Congenital Hypotrichosis in Belted Galloway Cattle

Genodermatosis such as hair disorders mostly follow a monogenic mode of inheritance. Congenital hypotrichosis (HY) belong to this group of disorders and is characterized by abnormally reduced hair since birth. The purpose of this study was to characterize the clinical phenotype of a breed-specific non-syndromic form of HY in Belted Galloway cattle and to identify the causative genetic variant for this recessive disorder. An affected calf born in Switzerland presented with multiple small to large areas of alopecia on the limbs and on the dorsal part of the head, neck, and back. A genome-wide association study using Swiss and US Belted Galloway cattle encompassing 12 cases and 61 controls revealed an association signal on chromosome 29. Homozygosity mapping in a subset of cases refined the HY locus to a 1.5 Mb critical interval and subsequent Sanger sequencing of protein-coding exons of positional candidate genes revealed a stop gain variant in the HEPHL1 gene that encodes a multi-copper ferroxidase protein so-called hephaestin like 1 (c.1684A>T; p.Lys562*). A perfect concordance between the homozygous presence of this most likely pathogenic loss-of-function variant and the HY phenotype was found. Genotyping of more than 700 purebred Swiss and US Belted Galloway cattle showed the global spread of the mutation. This study provides a molecular test that will permit the avoidance of risk matings by systematic genotyping of relevant breeding animals. This rare recessive HEPHL1-related form of hypotrichosis provides a novel large animal model for similar human conditions. The results have been incorporated in the Online Mendelian Inheritance in Animals (OMIA) database (OMIA 002230-9913).

Autosomal recessive hypotrichosis with loose anagen hairs associated with TKFC mutations

BACKGROUND

Loose anagen hair is a rare form of impaired hair anchorage in which anagen hairs that lack inner and outer root sheaths can be gently and painlessly plucked from the scalp. This condition usually occurs in children and is often self-limiting. A genetic basis for the disorder has been suggested but not proven. A better understanding the aetiology of loose anagen hair may improve prevention and treatment strategies.

OBJECTIVES

To identify a possible genetic basis of loose anagen hair using next-generation DNA sequencing and functional analysis of variants identified.

METHODS

In this case study, whole-exome sequencing analysis of a pedigree with one affected individual with features of loose anagen hair was performed.

RESULTS

The patient was found to be compound heterozygous for two single-nucleotide substitutions in TKFC resulting in the following missense mutations: c.574G> C (p.Gly192Arg) and c.682C> T (p.Arg228Trp). Structural analysis of human TKFC showed that both mutations are located near the active site cavity. Kinetic assays of recombinant proteins bearing either of these amino acid substitutions showed almost no dihydroxyacetone kinase or D-glyceraldehyde kinase activity, and FMN cyclase activity reduced to just 10% of wildtype catalytic activity.

CONCLUSIONS

TKFC missense mutations may predispose to the development of loose anagen hairs. Identification of this new biochemical pathobiology expands the metabolic and genetic basis of hypotrichosis.

Transcriptome Profiling and Differential Gene Expression in Canine Microdissected Anagen and Telogen Hair Follicles and Interfollicular Epidermis

The transcriptome profile and differential gene expression in telogen and late anagen microdissected hair follicles and the interfollicular epidermis of healthy dogs was investigated by using RNAseq. The genes with the highest expression levels in each group were identified and genes known from studies in other species to be associated with structure and function of hair follicles and epidermis were evaluated. Transcriptome profiling revealed that late anagen follicles expressed mainly keratins and telogen follicles expressed GSN and KRT15. The interfollicular epidermis expressed predominately genes encoding for proteins associated with differentiation. All sample groups express genes encoding for proteins involved in cellular growth and signal transduction. The expression pattern of skin-associated genes in dogs is similar to humans. Differences in expression compared to mice and humans include BMP2 expression mainly in telogen and high KRT17 expression in the interfollicular epidermis of dogs. Our data provide the basis for the investigation of the structure and function of canine skin or skin disease and support the use of dogs as a model for human cutaneous disease by assigning gene expression to specific tissue states.

Impact of Rheumatoid Arthritis on Alopecia: A Nationwide Population-Based Cohort Study in Taiwan

Objectives: Studies on the relationship between rheumatoid arthritis (RA) and alopecia areata (AA) are limited. This study investigated the effect of RA on alopecia areata risk in a nationwide cohort study. Methods: We analyzed 2000-2012 data from the Longitudinal Health Insurance Database in Taiwan. The follow-up period was extended up to the end of 2013. We defined RA as a diagnosis using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code 714.0 during at least three outpatient visits or one admission and the use of disease-modifying antirheumatic drugs (DMARDs) for >30 days. The enrollees with AA were identified using the ICD-9-CM code 704.01. We enrolled a comparison cohort comprising participants randomly matched by age and sex, with the same index date as that of the study cohort. Furthermore, we investigated alopecia risk by using Cox proportional-hazards regression models after propensity score matching for sex, age, comorbidities, and medication use. Results: In total, 2,905 patients with RA (74% women, mean age: 51.9 years) and 2,905 controls were followed for 22,276 and 25,732 person-years, respectively. Alopecia risk was 2.64-fold (95% confidence interval = 1.47-4.76) higher in patients with RA than in patients without RA after age, sex, comorbidities, and medication use were adjusted for. In addition, patients with thyroid disease presented considerable alopecia risk. Patients with RA in the younger age group (20-40 years) had the highest alopecia risk. Conclusions: Alopecia risk is significantly higher in patients with RA than in those without RA, particularly in the younger age group (20-40 years). RA assessment should be considered when examining patients with alopecia, especially young adults.

Loss-of-function variants in C3ORF52 result in localized autosomal recessive hypotrichosis

PURPOSE

Localized autosomal recessive hypotrichosis (LAH) has been associated with pathogenic variants in DSG4, encoding a desmosomal protein as well as in LIPH and LPAR6, encoding respectively lipase H, which catalyzes the formation of 2-acyl-lysophosphatidic acid (LPA), and lysophosphatidic acid receptor 6, a receptor for LPA. LPA promotes hair growth and differentiation. In this study we aimed at delineating the genetic basis of LAH in patients without pathogenic variants in these three genes.

METHODS

Variant analysis was conducted using exome and direct sequencing. We then performed quantitative reverse transcription polymerase chain reaction (RT-qPCR), immunofluorescence staining, immunoblotting, enzymatic, and coimmunoprecipitation assays to evaluate the consequences of potential etiologic variants.

RESULTS

We identified homozygous variants in C3ORF52 in four individuals with LAH. C3ORF52 was found to be coexpressed with lipase H in the inner root sheath of the hair follicle and the two proteins were found to directly interact. The LAH-causing variants were associated with decreased C3ORF52 expression and resulted in markedly reduced lipase H-mediated LPA biosynthesis.

CONCLUSION

LAH can be caused by abnormal function of at least three proteins which are necessary for proper LPA biosynthesis.