People with this rare genetic condition, also known as UHS, have “dry, frizzy, and wiry” hair that cannot be combed flat, usually starting from a young age between three months and 12 years of age, say researchers, including those from the University of Bradford in the UK.
While studies have been published on the condition since the 1970s, most have been case reports.
In the new study, published recently in the journal Jama Dermatology, scientists assessed one of the largest worldwide data collections of affected individuals, and have found the spectrum of genes involved in the condition.
Researchers analysed 107 unrelated patients with a suspected diagnosis of UHS and family members who were recruited worldwide from January 2013 to December 2021.
The findings confirm that one of the main causes of this rare condition is linked to mutations in the PADI3 gene along with roles played by two other genes – TCHH, and TGM3.
The variation observed among humans on Earth, such as in physical features, including hair colour, texture, and style, is due to small variations in genes between people.
Genes are the blueprints the body’s cells follow to produce proteins, and sometimes mutations in genes can lead to a change in the function of the protein they code.
In the new research, scientists found mutations in the genes PADI3, TCHH, and TGM3 that code for important proteins involved in the formation of hair fibres.
They say children may start showing signs of UHS if both parents carry the mutated genes, even if the parents themselves may not have the condition.
The new findings, researchers say, shed light on the factors influencing normal hair growth, and highlight the role played by different proteins in controlling hair shape and appearance.
“This cohort study extends and gives an overview of the genetic variant spectrum of UHS based on molecular genetic analyses of the largest worldwide collective of affected individuals, to our knowledge,” scientists wrote in the study.
“The discovery of pathogenic variants in PADI3, TCHH, and TGM3 may open a new avenue for clinicians and affected individuals by introducing molecular diagnostics for UHS,” they added.