according to Maria Hordinsky, MD, of the University of Minnesota, Minneapolis.
The ectodermal dysplasias are a heterogeneous group of disorders in which a main feature is the absent, incomplete, or delayed development of one or more of the appendages derived from ectoderm, such as the hair follicle, Dr. Hordinsky said in a presentation at Skin Disease Education Foundation’s Women’s & Pediatric Dermatology Seminar.
Patients with pure hair and nail ectodermal dysplasia generally present with absent or sparse eyebrows and eyelashes, as well as follicular papules on the scalp and fragile, irregular hair, Dr. Hordinsky said. The condition is caused by a mutation in a gene associated with the production of keratin. In another rare form of hereditary hair loss – hypotrichosis simplex – patients are born with normal hair but lose it gradually from the scalp during the middle of the first decade of life.
The inability to grow long hair characterizes short anagen syndrome, a congenital disorder not to be confused with loose anagen syndrome, Dr. Hordinsky said. Patients with short anagen syndrome experience an idiopathic short anagen phase and as a result, an increased number of hairs in the telogen phase. Children with short anagen syndrome have unusually short hair in early childhood. “Parents typically complain that their children exhibit short hair even though they have never had a haircut,” she explained.
Trichothiodystrophy, a rare autosomal recessive disease, is distinguished by hair that is brittle and sulfur deficient, Dr. Hordinsky said. She cited a review of 112 patients with trichothiodystrophy in which additional distinguishing features included developmental delay/intellectual impairment (86%), short stature (73%), and ichthyosis (65%).
Some cases of hair loss in children have a structural basis, Dr. Hordinsky noted. Structural hair abnormalities include fractures of the hair shaft, extraneous matter on the hair shaft, and hair shaft irregularities such as coiling or twisting, she said.
In trichoptilosis, extensive cuticle loss results in fraying and splitting of the hair shaft, while in patients with trichoclasis, a fractured hair is splinted by a partially intact cuticle.
In trichorrhexis nodosa, the most common type of structural hair abnormality, “intact nodes [of hair] resemble two paintbrushes thrust together,” Dr. Hordinsky explained. Trichorrhexis nodosa may be congenital or acquired, and occurs in children with mental retardation and argininosuccinic aciduria, she said.
A hair shaft abnormality is the culprit behind uncombable hair syndrome, which can be inherited or can occur sporadically, Dr. Hordinsky said. The key feature of the condition is unruly hair caused by a distinctive hair shaft defect, “possibly related to an abnormality in the inner root sheath.” Abnormal hairs usually become apparent at about 3-4 years of age, but eyebrows and eyelashes appear normal. Many patients have a silvery blonde tint to their hair because of how the abnormal hairs reflect light, she said.
Dr. Hordinsky is a consultant for P&G, Concert, Cassiopea, and BioAZ; and receives grant/research support from Aclaris, Allergan, and the National Alopecia Areata Foundation. SDEF and this news organization are owned by Frontline Medical Communications.