Loose Anagen Hair Associated with Wooly Hair Caused by a Heterozygous, Intronic Variant.

BACKGROUND

Loose anagen hair syndrome is a recently described genetic form of non-scarring alopecia that occurs in children and is due to poorly anchored hair shafts during the anagen phase. It can occur alone or in association with hair pathology or complex systemic phenotypes.

METHODS

We report a mother and daughter with loose anagen hair syndrome that is associated with wooly hair, although it shows variable expressivity. We studied the family using genomic sequencing and identified an intronic variant in their that segregates in an autosomal dominant pattern and is suspected to affect splicing in the tail domain of this hair follicle keratin. We studied this variant with a minigene experimental approach.

RESULTS

We provide experimental evidence that the identified intronic variant affects splicing in the tail domain, which is critical to the biomechanical properties of the keratin intermediate filaments. We demonstrate that it affects splicing by adding 12 bases to the mature transcript and consequently four amino acids to the peptide.

CONCLUSION

We suspect that this variant is responsible for the poorly anchored and finely curled hair in the mother and daughter, which leads to a proposed diagnosis of autosomal dominant wooly hair, as well as loose anagen hair syndrome. We thus expand the variant spectrum of and its associated phenotypes to include both disorders.