SEARCH · Search PubMed
Results for “Monilethrix”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Monilethrix: a review and case report.
Explore the source record for details and available documents.
Cuticle cell defects in lamellar ichthyosis hair and anomalous hair shaft syndromes visualized after detergent extraction.
BACKGROUND: The biochemical bases for fragility in most of the rare brittle hair shaft syndromes are unknown. The hypothesis being investigated in several syndromes is that the hair cuticle cells show defects in cross-linked protein features. Since transglutaminases stabilize protein structures by cross-linking them, hair from autosomal recessive lamellar ichthyosis patients lacking keratinocyte transglutaminase was examined to find whether this enzyme participates in hair shaft stabilization. METHODS: Hair shaft samples from patients afflicted with lamellar ichthyosis or several brittle hair syndromes were examined ultrastructurally by transmission electron microscopy after vigorous extraction with detergent and reducing agent to reveal cross-linked protein features. RESULTS: In hair cuticle cells from three patients with lamellar ichthyosis the marginal band (A layer) was present but nonuniform and subject to breakage, while in a fourth sample it was missing altogether. The exocuticle appeared less dense than in normal hair, consistent with extensive protein loss during detergent extraction. In cuticle cells from trichothiodystrophy hair, the exocuticle layer was essentially fully extractable in one sample, while in two others (from siblings) the exocuticle appeared less dense and the A layer was absent or greatly reduced in thickness. A sample of proximal trichorrhexis nodosa also displayed defects in cuticle cells, in which the endocuticle layer appeared subject to rupture. The outer cuticle cells in monilethrix hair displayed a thinning of the A layer and less dense exocuticle, while the cortex exhibited regions lacking remnant cell borders. Pili annulati hair displayed large gaps in the cortex, presumably reflecting the air-filled cavities characteristic of this syndrome, and wavy borders of some cuticle cells. CONCLUSIONS: Observations with autosomal recessive lamellar ichthyosis hair indicate that keratinocyte transglutaminase has a major role in maturation of the cuticle but appears unnecessary for stabilization of cell borders in the cortex. Defective cross-linking was also evident in cuticle cells of trichothiodystrophy and monilethrix.
Neurotrichosis: hair-shaft abnormalities associated with neurological diseases.
Six children with morphological hair-shaft abnormalities and neurological disease are presented, including two with Pollitt syndrome, one with biotin deficiency, two with Menkes diseases and one with argininosuccinic aciduria. The child with biotin deficiency grew normal hair following oral biotin therapy. Although the hair-shaft abnormalities may be seen with light microscopy (LM), they are best visualised with scanning electron-microscopy (SEM). Pili torti may be mistaken for monilethrix by LM, but SEM shows the true defect. A review of the literature shows that these hair-shaft abnormalities (trichorrhexis nodosa, monilethrix and pili torti) are not specific or pathognomonic, but do indicate a group of neurological disorders, including potentially treatable inborn errors of metabolism. The term 'neurotrichosis' is suggested to classify this group of disorders.
[Hair disorders and neurological impairments (neurotricosis): three new cases].
Three children with hair-shaft abnormalities and neurological disorders are reported. The first case is a young girl with monilethrix and Friedreich's ataxia that presented IgG and IgA deficiency, without telangiectasis. The second patient is a young girl with monilethrix and HMSN I. The third patient is a boy with a peculiar face, hypotrichosis and pili torti; he was mentally retarded and had epileptic seizures. His diagnosis was compatible with Noonan's syndrome or with a cardio-facio-cutaneous syndrome, because of the existence of hyperkeratosis and the neurological features. It is our aim to emphasize the heterogeneity of neurotrichosis, whose limits are not well established and whose manifestations are shared by some of them.
Hair keratinization in health and disease.
The cells of the epidermis and its derivative, the hair follicle, undergo processes of terminal differentiation that involves the synthesis and assembly of classes of protein and enzymes to form the stratum corneum of the epidermis, and the hair fiber and its cuticle. Using genetic linkage and DNA sequencing methods, we now know that mutations in several genes encoding epidermal keratins or a transglutaminase enzyme cause ichthyosis-related diseases. Similar methods have now suggested that mutations in hair keratin genes underlie some cases of monilethrix, and a deficiency in a cuticle lipid metabolizing enzyme causes maple syrup urine disease. It is to be expected that further application of these methods will elucidate the molecular bases of other genetic hair diseases.
Structural stability of wild type and mutated alpha-keratin fragments: molecular dynamics and free energy calculations.
The objective of this study is to investigate the influence of point mutations on the structural stability of coiled coil fragments of the human hair intermediate filament by molecular dynamics simulations and free energy calculations. Mutations in the helix termination motif of human hair keratin gene hHb6 seem to be connected to the hereditary hair dystrophy Monilethrix. The most common mutations reported are Glu413Lys and Glu413Asp, located at the C-terminal end of the coiled coil 2B rod domain of the IF. According to our simulations, significant conformational changes of the side chains at the mutation and neighboring sites occur due to the Glu413Lys mutation. Furthermore, the differences in electrostatic interactions cause a large change in free energy during transformation of Glu413 to Lys calculated by the thermodynamic integration approach. It is speculated that the structural rearrangement necessary to adapt the interactions in the mutated coiled coil leads to changes in the IF assembly or its stability. The second mutation, Glu413Asp, only leads to a small value of the calculated free energy difference that is within the error limits of the simulations. Thus, it has to be concluded that this mutation does not affect the coiled coil stability.
Lanceolate hair-J (lahJ): a mouse model for human hair disorders.
Lanceolate hair-J (lahJ) arose spontaneously in 1994 on the DBA/1LacJ inbred background at The Jackson Laboratory. Mutant mice were runted, alopecic, and lacked vibrissae. As they aged, their skin wrinkled. Affected mice developed a noninflammatory, proliferative skin disease with follicular dystrophy. Hair fibers developed a number of abnormalities including periodic nodules along the shaft (trichorrhexis nodosa), compaction resembling trichorrhexis invaginata, spiral fractures, broken tips, and lance-shaped tips. This mutation exhibits some characteristics that resemble an autosomal recessive ichthyosiform disease that occurs in humans characterized in part by peculiar, invaginating, multinodal, hair shaft abnormalities known as Netherton's syndrome. Periodic nodules also resemble the human genetic based disease monilethrix. This autosomal recessive mouse mutation, allelic with lanceolate hair (lah), based on breeding studies, is located on mouse Chromosome 18, within a cluster of genes coding for adhesion molecules. Homozygotes for either of these allelic mouse mutations have elevated serum IgE levels, a feature also common with human Netherton's syndrome.
Human keratin diseases: the increasing spectrum of disease and subtlety of the phenotype-genotype correlation.
Keratins are obligate heterodimer proteins that form the intermediate filament cytoskeleton of all epithelial cells. Keratins are tissue and differentiation specific and are expressed in pairs of types I and II proteins. The spectrum of inherited human keratin diseases has steadily increased since the causative role of mutations in the basal keratinocyte keratins 5 and 14 in epidermolysis bullosa simplex (EBS) was first reported in 1991. At the time of writing, mutations in 15 epithelial keratins and two trichocyte keratins have been associated with human diseases which include EBS, bullous congenital ichthyosiform erythroderma, epidermolytic palmoplantar keratoderma, ichthyosis bullosa of Siemens, diffuse and focal non-epidermolytic palmoplantar keratoderma, pachyonychia congenita and monilethrix. Mutations in extracutaneous keratins have been reported in oral white sponge naevus and Meesmann's corneal dystrophy. New subtleties of phenotype-genotype correlation are emerging within the keratin diseases with widely varying clinical presentations attributable to similar mutations within the same keratin. Mutations in keratin-associated proteins have recently been reported for the first time. This article reviews clinical, ultrastructural and molecular aspects of all the keratin diseases described to date and delineates potential future areas of research in this field.
Hair shaft abnormalities: Part I.
The light microscopic and electron microscopic appearances of the normal hair are briefly described. The major hair shaft abnormalities are reviewed in two parts, discussing clinical characteristics, light and electron microscopy and, where information is available, the pathogenesis of these rare conditions. Part I describes monilethrix, pili torti and trichorrhexis nodosa.
Human keratin diseases: hereditary fragility of specific epithelial tissues.
Keratins are heteropolymeric proteins which form the intermediate filament cytoskeleton in epithelial cells. Since 1991, mutations in several keratin genes have been found to cause a variety of human diseases affecting the epidermis and other epithelial structures. Epidermolysis bullosa simplex (EBS) was the first mechanobullous disease for which the underlying genetic lesion was found, with mutations in both the K5 and K14 genes rendering basal epidermal keratinocytes less resilient to trauma, resulting in skin fragility. The site of mutation in the keratin protein correlates with phenotypic severity in this disorder. Since mutations were identified in the basal cell keratins, the total number of keratin genes associated with diseases has risen to eleven. The rod domains of suprabasal keratins K1 and K10 are mutated in bullous congenital ichthyosiform erythroderma (BCIE; also called epidermolytic hyperkeratosis, EH) and mosaicism for K1/K10 mutations results in a nevoid distribution of EH. An unusual mutation in the VI domain of K1 has also been found to cause diffuse non-epidermolytic palmoplantar keratoderma (DNEPPK). Mutations in palmoplantar specific keratin K9 cause epidermolytic palmoplantar keratoderma (EPPK) and mutations in the late differentiation suprabasal keratin K2e cause ichthyosis bullosa of Siemens (IBS). In the last year or so, mutations were discovered in differentiation specific keratins K6a and K16 causing pachyonychia congenita type 1 and K17 mutations occur in pachyonychia congenita type 2. K16 and K17 mutations have also been reported to produce phenotypes with little or no nail changes: K16 mutations can present as focal non-epidermolytic palmoplantar keratoderma (NEPPK) and K17 mutations can result in a phenotype resembling steatocystoma multiplex. Recently, mutation of mucosal keratin pair K4 and K13 has been shown to underlie white sponge nevus (WSN). This year, the first mutations in a keratin-associated protein, plectin, were shown to cause a variant of epidermolysis bullosa associated with late-onset muscular dystrophy (MD-EBS). An unusual mutation has been identified in K5 which is responsible for EBS with mottled pigmentation and genetic linkage analysis suggests that the hair disorder monilethrix is likely to be due to a mutation in a hair keratin. The study of keratin diseases has led to a better understanding of the importance of the intermediate filament cytoskeleton and associated connector molecules in maintaining the structural integrity of the epidermis and other high stress epithelial tissues, as well as allowing diagnosis at the molecular level thus facilitating prenatal testing for this heterogeneous group of genodermatoses.
Oculodentodigital dysplasia syndrome. Report of four cases.
Four cases of oculodentodigital dysplasia are reported. Three cases are from the same family, father and two daughers. These three cases have the characteristics typical of this disorder: narrow nose, hypoplastic alae nasi, microphthalmia, defects of the teeth, syndactylyl of the IV and V fingers, and skeletal anomalies. The fourth case differs from the earlier reported cases; he has all the typical findings of oculodentodigital dysplasia but in addition he shows features not previously reported, namely exceptionally poor vision, mental retardation, monilethrix and pili annuli changes of the hair.
Light microscopic examination of scalp hair samples as an aid in the diagnosis of paediatric disorders: retrospective review of more than 300 cases from a single centre.
BACKGROUND: Microscopic examination of scalp hair can provide important diagnostic information in a range of paediatric conditions. It is a non-invasive and cost effective investigation, which is not widely performed. AIMS: To examine retrospectively the value of hair examination by light microscopy, including polarising microscopy, in a specialist paediatric pathology department during a 15 year period (1989-2004) and to describe the morphological abnormalities indicative of specific paediatric conditions. METHODS: Three hundred and twenty two hair samples were submitted. Microscopic changes were analysed in the light of clinical information categorised as: (1) erythroderma, (2) neurological impairment, (3) immunological/haematological defect, (4) ectodermal dysplasia, (5) abnormal hair only, and (6) non-specific/absent clinical details. RESULTS: Abnormalities were evident in 49% of the samples. In 25%, the changes were compatible with specific diagnoses including Menkes disease, Netherton's syndrome, trichothiodystrophy, Griscelli and Chediak-Higashi syndromes, monilethrix, uncombable hair, and loose anagen syndromes. In respect of the clinical presentation groups noted above, diagnostic changes were seen in 41%, 32%, 33%, 0%, 29%, and 0%, respectively. CONCLUSIONS: Morphological light microscopic examination of scalp hair is an inexpensive, rapid, and non-invasive investigation, which can provide valuable diagnostic information in a range of paediatric conditions.
Regression and disappearance of clinical symptoms in some cases of genodermatoses.
Genetic skin diseases are usually thought of as stable phenotypes caused by a mutant gene. However, a review of the literature on genodermatoses and my personal experience with a number of these disorders show that the concept of a stable phenotype is not always true. A number of genodermatoses actually show a regression of symptoms. Among these are monilethrix, several types of erythrokeratoderma, several forms of palmoplantar keratoderma such as the varians Wachters type and the Richner-Hanhart syndrome, and some forms of epidermolysis bullosa, for example the Dowling-Meara type. Three different reasons possibly underlying the regression of symptoms in genetic diseases are briefly discussed: (1) environmental factors, (2) hormonal influences and (3) movable, transposable elements causing instability of the genome.
Retinoids in disorders of keratinization: their use in adults.
Hereditary disorders of keratinization may be a considerable handicap. Oral treatment with retinoids has been shown to be effective in many of these diseases. In the group of ichthyoses, the best results can be obtained in the various types of nonbullous congenital ichthyosis (erythrodermic autosomal recessive lamellar ichthyosis, nonerythrodermic autosomal recessive lamellar ichthyosis, autosomal dominant lamellar ichthyosis). It should be borne in mind, however, that retinoid therapy alone cannot lead to a complete response of these forms of ichthyosis and that this treatment cannot replace an appropriate topical treatment. During continuous treatment with etretinate a reduction of the dosis to 0.5 mg/kg is often necessary. Etretinate treatment of bullous congenital ichthyosiform erythroderma is more difficult, and it is advisable to begin with a low dosis of 0.25-0.5 mg/kg. The epidermolytic form of palmoplantar keratoderma is in our opinion no indication for retinoid treatment which seems to result inevitably in large erosions. Good or excellent results have been seen in other forms of palmoplantar keratoderma including mal de Meleda, Papillon-Lefèvre syndrome, erythrokeratodermia variabilis, verrucous epidermal nevi, Darier disease and pityriasis rubra pilaris. In patients with Darier disease it is wise to begin with a relatively low dosage of 0.5 mg/kg and to adjust the dosage to the further course of the disease. The same is true for the ichthyosis seen in the Netherton syndrome, which may be either a diffuse hyperkeratosis or ichthyosis linearis circumflexa. In view of the fact that any inherited keratinization disorder requires long-term treatment, the risk of bone toxicity should be carefully weighed against the benefit of this therapy. The results so far obtained indicate that the effect of etretin is comparable to that of etretinate in the treatment of inherited keratinization disorders. Intermittent therapy should be tried whenever possible. A combination therapy seems reasonable in pityriasis rubra pilaris of the adult type. We have seen good results by combination with PUVA treatment. Autosomal dominant ichthyosis vulgaris and X-linked recessive ichthyosis are inappropriate to treat with oral retinoid therapy because these diseases are too mild. Papillomatous epidermal nevi should also be excluded because they do not respond to the drug. Hailey-Hailey disease may even be worsened by this treatment. According to our experience, oral retinoid therapy has no effect in monilethrix.
The molecular genetics of keratin disorders.
Keratins are the type I and II intermediate filament proteins which form a cytoskeletal network within all epithelial cells. They are expressed in pairs in a tissue- and differentiation-specific fashion. Epidermolysis bullosa simplex (EBS) was the first human disorder to be associated with keratin mutations. The abnormal keratin filament aggregates observed in basal cell keratinocytes of some EBS patients are composed of keratins K5 and K14. Dominant mutations in the genes encoding these proteins were shown to disrupt the keratin filament cytoskeleton resulting in cells that are less resilient and blister with mild physical trauma. Identification of mutations in other keratin genes soon followed with attention focussed on disorders showing abnormal clumping of keratin filaments in specific cells. For example, in bullous congenital ichthyosiform erythroderma, clumping of filaments in the suprabasal cells led to the identification of mutations in the suprabasal keratins, K1 and K10. Mutations have now been identified in 18 keratins, all of which produce a fragile cell phenotype. These include ichthyosis bullosa of Siemens (K2e), epidermolytic palmoplantar keratoderma (K1, K9), pachyonychia congenita (K6a, K6b, K16, K17), white sponge nevus (K4, K13), Meesmann's corneal dystrophy (K3, K12), cryptogenic cirrhosis (K8, K18) and monilethrix (hHb6, hHb1).In general, these disorders are inherited as autosomal dominant traits and the mutations act in a dominant-negative manner. Therefore, treatment in the form of gene therapy is difficult, as the mutant gene needs to be inactivated. Ways of achieving this are actively being studied. Reliable mutation detection methods from genomic DNA are now available. This enables rapid screening of patients for keratin mutations. For some of the more severe phenotypes, prenatal diagnosis may be requested and this can now be performed from chorionic villus samples at an early stage of the pregnancy. This review article describes the discovery of, to date, mutations in 18 keratin genes associated with inherited human diseases.