Alopecia universalis congenita (ALUNC) is a rare disorder characterized by generalized absence of hair at or shortly after birth. There are various forms of this condition, with inheritance showing autosomal recessive, dominant or even X-linked forms. However, the autosomal recessive form of this condition is the most common, and also the most severe form of the disease. Patients with this recessive form exhibit a complete absence of hair development, affecting all scalp and body hair. Affected individuals may show a broad spectrum of follicle alterations, ranging from absence of hair in the follicles to complete absence of the hair follicles themselves. Not only are the scalp hairs affected, but so are the axillary and pubic regions, eyebrows, and eyelashes. Neonates may have a few sparse hairs at the crown of head, which fall off within a few weeks and never regrow. The skin is otherwise unaffected, as evidenced by the unremarkable dermis and epidermis seen upon biopsy of the skin.
Linkage analysis was used to map the gene responsible for the autosomal recessive alopecia universalis, which pointed towards the short arm of chromosome 8. The locus, initially designated as ALUNC, was later revealed to carry a gene coding for a nuclear receptor co-repressor called the hairless gene (HR), which in its mutated form has been found to be responsible for the pathogenesis of the disease condition.
Kenue and Al-Dhafri (1994) described a large consanguineous Omani kindred with 22 members (13 females, 9 males) from six generations affected with congenital atrichia. A typical autosomal recessive inheritance could be noticed. None of the patients showed any ectodermal defects. In 1998, Cichon et al. were able to characterize the cDNA sequence encoding the human hairless gene and link it to the disease condition in the family of Kenue and Al-Dhafri (1994). Affected individuals were born with fine hair and displayed hair loss starting two months after birth. Patients showed universal absence of scalp, eyebrows, pubic and axillary hair, but scanty eyelashes on the upper lid were seen in few subjects. No hair follicles were detected in a skin biopsy taken from an 11 year old boy.
Betz et al. (2007) described a Saudi family affected with Alopecia Universalis Congenita. The proband was a 2-month-old girl born to half first-cousin consanguineous parents. She was born with normal hair, but progressively lost it. At the time of examination, she had only a few hairs remaining at the vertex. On her second examination at 8-months, she had hardly any hair left. There were no other signs or symptoms. She had an older brother who was born without hair. The parents were normal, as were two other siblings. The proband had an affected cousin, also born to half first cousin parents. Molecular analysis revealed a homozygous insertion mutation in the HR gene in the proband and her affected brother.