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Dermatology > PEDIATRIC DISEASES
Monilethrix
Article Last Updated: Jun 4, 2007
AUTHOR AND EDITOR INFORMATION
Section 1 of 9  
Author: Robert A Schwartz, MD, MPH, Professor and Head of Dermatology, Professor of Medicine, Professor of Pediatrics, Professor of Pathology, Professor of Preventive Medicine and Community Health, UMDNJ-New Jersey Medical School
Robert A Schwartz is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American College of Physicians, and Sigma Xi
Coauthor(s):
Malgorzata Alexiewicz-Slowinska, MD, Consulting Dermatologist, Group Medical Practice, Poznan, Poland
Editors: Carrie L Kovarik, MD, Assistant Professor, Department of Dermatology and Dermatopathology, University of Pennsylvania School of Medicine; David F Butler, MD, Professor of Dermatology, Texas A&M University College of Medicine; Director, Division of Dermatology, Scott and White Clinic; Director Dermatology Residency Training Program, Scott and White Clinic; Camila K Janniger, MD, Clinical Professor of Dermatology, Clinical Associate Professor of Pediatrics, Chief of Pediatric Dermatology, New Jersey Medical School; Glen H Crawford, MD, Assistant Clinical Professor, Department of Dermatology, University of Pennsylvania School of Medicine; Chief, Division of Dermatology, The Pennsylvania Hospital; Dirk M Elston, MD, Director, Department of Dermatology, Geisinger Medical Center
Author and Editor Disclosure
Synonyms and related keywords:
beaded hair, nodose hair, moniliform hair, hair fragility, patchy dystrophic alopecia, breakage of hair, alopecia, keratosis pilaris, koilonychia, follicular keratosis
Background
Monilethrix is an autosomal dominant disorder characterized by a beaded appearance of the hair due to periodic thinning of the shaft. The phenotype results in hair fragility and patchy dystrophic alopecia. The term monilethrix is derived from monile (Latin), which means necklace, and thrix (Greek), which means hair. This term indicates the resemblance of the hair to a string of beads or a necklace. Monilethrix is also known as nodose hair. In 1897, Walter Smith first described monilethrix (pili moniliformes [Latin]). Regular nodes and internodes that lead to breakage of the hair and varying degrees of alopecia characterize this hair-shaft anomaly. Monilethrix is inherited as an autosomal dominant trait with high penetrance but variable expressivity. However, autosomal recessive inheritance for this disease has been sporadically reported.1
Pathophysiology
The etiology remains obscure. Results of genetic linkage analysis suggest that monilethrix is likely caused by a mutation in a hair keratin. Mutations in the human hair basic keratins hHb1 and hHb6 have been described with this disorder.2 The most frequent mutation is the E413K mutation in hHb6.3 These mutations in the helix-encoding region in the hair-specific keratins hHb1 and hHb6 may represent different novel heterozygous point mutations of the same codon in exon 7 of the hHb6 gene.4 A mutational hotspot may exist in the helix termination motif of hHb6.5 A missense mutation in the type II hair keratin hHb3 has been shown to be associated with monilethrix.6 Twenty-one affected individuals in 2 unrelated monilethrix families of Indian origin were studied, and a point mutation (g.4624G>A) in the HTM motif (exon-7) of the KRTHB6 gene was found in all the affected members, leading to E413K change in this basic keratin.7 An autosomal recessive form of monilethrix was found to be caused by mutations in DSG4 while evaluating 12 Jewish families from Iraq, Iran, and Morocco, with microscopic findings of monilethrix, but with no evidence of vertical transmission.1 Sequencing of the main candidate gene from this region revealed 4 different mutations in desmoglein 4 (DSG4). To date, whether monilethrix is a disorder of the function or structure of the hair has not been determined.
Frequency
United States
No data are available.
International
No data are available.
Race
- No racial predilection is evident.
- The condition is not linked to any particular hair color.
Sex
No sex limitation is evident.
Age
The onset is during infancy.
History
- Course
- Monilethrix is a lifelong disease.
- Internodal fragility leads to breakage of hair and varying degrees of alopecia.
- Symptoms spontaneously regress during puberty and pregnancy, but the condition never disappears completely.
- Affected persons are generally healthy.
- Associated defects
- Keratosis pilaris is almost invariably associated with monilethrix. Sites of predilection are the scalp, nape of the neck, and extensor surfaces of the upper arm and thigh. No evidence suggests that keratosis pilaris can lead to the formation of beaded hair.
- Koilonychia is commonly associated with monilethrix.
- A wide variety of concomitant ectodermal defects are reported in the literature. Examples include dental abnormalities, juvenile cataracts, and some neurologic defects that appear as a cognitive deficiency or epilepsy.
Physical
- Lanugo hair usually appears normal at birth. Several months later, it is replaced by moniliform hair, which is dry, brittle, fragile, and lusterless.
- The hair breaks spontaneously to 0.5-2.5 cm. Broken short hair looks as if it has been burnt.
- Monilethrix occurs mainly on the scalp, predominantly on the occiput and nape and occasionally on other scalp areas. Scalp involvement can be widespread or circumscribed.
- The eyelashes, eyebrows, pubic, axillary, and limb hair are occasionally involved.
- Monilethrix is associated with follicular keratosis (horny follicular papules).
- Patients with monilethrix and a prolonged clinical course of several years' duration may have cutaneous atrophy (aplasia pilorum moniliformes [Latin]).
Causes
See Pathophysiology.
Trichorrhexis Invaginata (Netherton Syndrome or Bamboo Hair)
Other Problems to be Considered
Pili torti
Trichorrhexis nodosa
Pseudomonilethrix
Other Tests
- Light microscopy, with macroscopic examination, aids in diagnosis.
- The hair shaft has regular, elliptical, fusiform, or spindle-shaped swellings (nodes) that are 0.7-1.0 mm in diameter and separated by constricted internodes.
- The nodes have the diameter of normal hair and are medullated, whereas the internodes have no medulla and are the sites of fracture.
- Pigment is present in both segments.
- Scanning electron microscopy may reveal useful findings.
- All nodes demonstrate normal or worn transverse cuticular scales.
- Internodes show a dense longitudinal pattern of scales and ridging.
- Dermoscopy can be used as a tool for rapid diagnosis of monilethrix.8 It may show hair shafts with uniform elliptical nodes and intermittent constrictions, with hairs bent regularly at multiple locations and having a tendency to fracture at constriction sites.
Histologic Findings
Landau et al recently described an easy way to diagnose severe neonatal monilethrix.9 One can scrape the scalp with a glass slide, collect epidermal cells and rudimentary hair fragments, and examine the unstained specimen by using a microscope. One should find single or paired beads of typical monilethrix hair.
Medical Care
No effective treatment is available.
- A wig can be used.
- Some report spontaneous improvement.
- The systemic administration of vitamins, retinoids, griseofulvin, oral contraceptives, steroids, radiation therapy and external desquamative ointments, steroid preparations, and minoxidil does not show impressive results. A 7-year-old girl treated with oral acitretin had good clinical and cosmetic results, but clinical symptoms recurred after discontinuation of acitretin therapy.10
- The avoidance of trauma is the most effective method of managing this anomaly.
- Congenitally abnormal hair tends to have an increased susceptibility to weathering and cosmetic damage (eg, sunlight exposure, dyeing, bleaching, perming, curling), which can prevent hair from growing to its maximum length.
Deterrence/Prevention
- The avoidance of trauma is the most effective method of managing this anomaly.
- Because congenitally abnormal hair tends to have an increased susceptibility to weathering and cosmetic damage, patients should avoid exposing their hair to the following:
- Sunlight
- Dyes
- Bleaches
- Chemicals used in permanent waving
- Curling devices
Prognosis
- Monilethrix is a lifelong disease.
- Symptoms spontaneously regress during puberty and pregnancy, but the condition never disappears completely.
| Media file 1:
Lusterless, dry, brittle hair with alopecia and keratosis pilaris mainly on the occiput. The hair of this 4-year-old boy was never cut. |
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| Media file 2:
Photomicrograph shows the regular nodes and internodes of the hair shaft in monilethrix, or pili moniliformes (original magnification X200). |
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| Media file 3:
Photomicrograph shows the regular nodes and internodes of the hair shaft in monilethrix, or pili moniliformes (original magnification X200). |
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| Media file 4:
Monilethrix that affects the entire scalp in the mother of the boy in Media File 1. |
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| Media file 5:
Monilethrix that affects the entire scalp in the mother of the boy in Media File 1. |
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- Zlotogorski A, Marek D, Horev L, Abu A, Ben-Amitai D, Gerad L, et al. An autosomal recessive form of monilethrix is caused by mutations in DSG4: clinical overlap with localized autosomal recessive hypotrichosis. J Invest Dermatol. Jun 2006;126(6):1292-6. [Medline].
- Korge BP, Hamm H, Jury CS, Traupe H, Irvine AD, Healy E, et al. Identification of novel mutations in basic hair keratins hHb1 and hHb6 in monilethrix: implications for protein structure and clinical phenotype. J Invest Dermatol. Oct 1999;113(4):607-12. [Medline].
- Muramatsu S, Kimura T, Ueki R, Tsuboi R, Ikeda S, Ogawa H. Recurrent E413K mutation of hHb6 in a Japanese family with monilethrix. Dermatology. 2003;206(4):338-40. [Medline].
- Pearce EG, Smith SK, Lanigan SW, Bowden PE. Two different mutations in the same codon of a type II hair keratin (hHb6) in patients with monilethrix. J Invest Dermatol. Dec 1999;113(6):1123-7. [Medline].
- Horev L, Glaser B, Metzker A, Ben-Amitai D, Vardy D, Zlotogorski A. Monilethrix: mutational hotspot in the helix termination motif of the human hair basic keratin 6. Hum Hered. Sep-Oct 2000;50(5):325-30. [Medline].
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- Khandpur S, Bairwa NK, Reddy BS, Bamezai R. A study of phenotypic correlation with the genotypic status of HTM regions of KRTHB6 and KRTHB1 genes in monilethrix families of Indian origin. Ann Genet. Jan-Mar 2004;47(1):77-84. [Medline].
- Rakowska A, Slowinska M, Czuwara J, Olszewska M, Rudnicka L. Dermoscopy as a tool for rapid diagnosis of monilethrix. J Drugs Dermatol. Feb 2007;6(2):222-4. [Medline].
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Monilethrix excerpt Article Last Updated: Jun 4, 2007
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