Hypotrichosis congenita of Marie Unna

ARTICLE

The patient, a woman aged 54, was born with normal hair. With age, particularly during adolescence, the hair became sparse on the scalp and formed a peculiar pattern reminiscent of androgenetic alopecia of the Ludwig type, but somewhat asymmetrical (Fig. 1). The remaining hair was rather coarse. Eyebrows and eyelashes were almost absent and the body hair was sparse. Her nails and teeth were normal and other ectodermal structures were likewise unaffected. Sweating was normal. Her general physical and mental development was normal. Hypotrichosis congenita of Marie Unna

Comment

The patient reported that her sister had similar hair problems. The patient's sister, aged 50, showed almost the same clinical findings and clinical course (Fig. 2). Evaluation of the family history revealed 8 members affected to various degrees by the same hair abnormalities, suggesting an autosomal dominant mode of inheritance (Fig. 3). Light microscopical examination of a knotted hair shaft showed an iron-wire appearance of the knot (Fig. 4).

The disorder is characterized by a distinctive structural defect of the hair shaft and generalized hair loss [1-6]. At birth, scalp hair is of almost normal appearance. During early childhood terminal hair of an unusual type appears. The hair is coarse, unruly, and uncombable, resulting in the impression that the children wear an ill-fitting wig. After puberty, the hair becomes increasingly sparse, especially at the vertex, and this balding may be confused with androgenetic alopecia. Eyelashes are often absent, and eyebrows, axillary and pubic hair are usually very sparse. The remaining body hair is likewise extremely sparse or absent. The mucous membranes, nails, and other ectodermal structures as well as the general physical and mental development are normal. However, widely spaced upper incisor teeth were noted by Roberts et al. [7] in 50% of affected individuals.

Microscopical examination of the abnormal hair reveals irregular variations in shaft diameter. On scanning electron microscopic examination, the hair shafts show irregular twisting and flattening as well as an irregular cuticula.

Histopathologically, the epidermis may show moderate hyperkeratosis. Horny masses fill some follicular ostia. Many follicles are in various stages of atrophy, but their sebaceous glands are preserved. Hyalinosis of the dermis is conspicuous at the sites of atrophic follicles. In later stages the follicles are reduced in number (Fig. 5) and foreign body granulomas surround some follicular remnants.

This disorder represents a genetically determined defect in the sulfur-containing interfibrillar substance of the inner root sheath, cuticular cells, and cortex of the hair, resulting in deficient bonding of keratin fibrils into larger fibers. The abnormally structured hair is vulnerable to torsion damage but not to longitudinal strain unless the former has fractured the keratin fibers [5].

Hypotrichosis congenita of Marie Unna is transmitted as an autosomal dominant trait and the gene maps to a locus close to, but apparently distinct from, the hairless gene on 8p22-21 [8, 9].

Although this disease does not imply serious functional problems, it creates a cosmetic handicap. No effective treatment is currently available. A wig is at present the best help for the patients.

References

1. Unna M. Über hypotrichosis congenita hereditaria. Derm Wochenschrift 1925; 81: 1167-78.

2. Ludwig E. Hypotrichosis congenita hereditaria. Typ. Marie Unna. Arch Derm Syph 1953; 196: 261-78.

3. Souied E, Amalric P, Chauvet ML, Chevallier C, Le Hoang P, Munnich A, et al. Unusual association of juvenile macular dystrophy with congenital hypotrichosis: occurrence in two siblings suggesting autosomal recessive inheritance. Ophthalmic Genet 1995; 16: 11-5.

4. Marren P, Wilson C, Dawber RPR, Walshe MM. Hereditary hypotrichosis (Marie-Unna type) and juvenile macular degeneration (Stargardt's maculopathy). Clin Exp Dermatol 1992; 17: 189-91.

5. Solomon LM, Esterly LB, Medenica M. Hereditary trichodysplasia: Marie Unna's hypotrichosis. J Invest Dermatol 1971; 57: 389-400.

6. Argenziano G, Sammarco E, Rossi A, Delfino M, Calvieri S. Marie Unna hereditary hypotrichosis. Eur J Dermatol 1999; 9: 278-80.

7. Roberts JL, Whiting DA, Henry D, Basler G, Woolf L. Marie Unna congenital hypotrichosis: clinical description, histopathology, scanning electron microscopy of a previously unreported large pedigree. J Invest Dermatol 1999; 114: 261-7.

8. Van Steensel M, Smith FJD, Steijlen PM, Kluijt I, Stevens HP, Messenger A, et al. The gene for hypotrichosis of Marie Unna maps between D8S258 and D8S298: exclusion of the hr gene by cDNA and genomic sequencing. Am J Hum Genet 1999; 65: 413-9.

9. Sreekumar GP, Roberts JL, Wong CQ, Stenn KS, Parimoo S. Marie Unna hereditary hypotrichosis gene maps to human chromosome 8p21 near hairless. J Invest Dermatol 2000; 114: 595-7.