Hypotrichosis simplex

ARTICLE

An 8-year-old boy was referred to our clinic because of his sparse hair.

Physical examination showed a boy of normal growth. There was no obvious intellectual or neurological impairment. The scalp hair was sparse, thin and curly (Figs. 1 and 2). Eyelashes, eyebrows and body hair were normal. There were no signs of dysplasia on the skin, nails or teeth. The previous medical history was unremarkable. Normal lanugo hair was present at birth.

Analysis of his hair under a light and polarizing microscope did not reveal any nodes, constructions or banding.

Hypotrichosis simplex

Comment

This case presents the typical features of hypotrichosis simplex. Normal lanugo hair is present at birth, but it is insufficiently replaced by terminal hair. This hypotrichosis becomes more obvious in later childhood [3].

Hypotrichosis simplex is inherited as an autosomal dominant trait that was recently mapped to 6p21.3 [5]. The present case may represent a new mutation as there are no other affected family members.

Hereditary hypotrichosis simplex is often misdiagnosed. It is more common than one might assume from studying the literature [3].

References

1. Toribio J, Quinones PA. Hereditary hypotrichosis simplex of the scalp: evidence for autosomal dominant inheritance. Br J Dermatol 1974; 91: 687-96.

2. Diaz ER, Blasco GF, Pascual AM, Armijo M. Hereditary hypotrichosis simplex of the scalp. Dermatology 1995; 191: 139-41.

3. Happle R. Genetic defects involving the hair. In: Orfanos CE, Happle R, eds. Hair and hair diseases. Berlin: Springer, 1989: 325-62.

4. Just M, Ribera M, Fuente MJ, Bielsa I, Ferrandis C. Hereditary hypotrichosis simplex. Dermatology 1998; 196: 339-42.

5. Betz RC, Lee YA, Bygum A, Brandrup F, Bernal AI, Toribio J, Alvarez JI, Kukuk GM, Rasmussen HB, Wienker TF, Reis A, Propping P, Kruse R, Cichon S, Nöthen MM. Am J Hum Genet 2000; 66: 1979-83.