Genetic Hair Disorders: A Review

Abstract

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.

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

“…To date, many molecules involved in skin homeostasis have been extensively studied and their role in disease development in humans and rodents is well known [ 30 , 31 , 32 ]. Additionally, in domestic animals, numerous gene variants involved in genodermatoses were identified by whole genome sequencing and other approaches [ 33 ].…”

Autosomal recessive hypotrichosis with loose anagen hairs associated with TKFC mutations*

“…Inherited forms of hypotrichosis are genetically heterogeneous, with> 30 genes implicated in a spectrum of syndromic and nonsyndromic Mendelian disorders 1 . However, in some forms of hair loss the genetic contribution is more circumspect.…”

Sparse Hair on the Scalp

“…The autosomal-recessive form is caused by mutations in the DSG4 gene, coding for the desmoglein 4 protein. 2 Trichoscopy or light microscopy is essential to establish a diagnosis of monilethrix. Trichoscopy is an easy and rapid tool that is utilized to illustrate the beaded appearance of the hair shafts.…”

“…Therefore, thorough clinical examination of other ectodermal structures such as the nails and teeth is crucial as well as obtaining a detailed family history and review of systems to exclude other syndromes. 2 Hypotrichosis simplex is characterized by hair loss exclusively on the scalp, sparing other ectodermal structures and with no systemic abnormalities. Ectodermal dysplasia is a heterogeneous group of disorders affecting not only the hair but also the teeth, nails, and sweat glands.…”

“…Ectodermal dysplasia is a heterogeneous group of disorders affecting not only the hair but also the teeth, nails, and sweat glands. 2 Pili torti is another rare genetic hair disorder that is characterized by twisting of the hair fiber on its own axis. It presents clinically as sparse, depigmented, lusterless hair that is easily broken.…”