Researchers discover a new gene for hair loss

Hypotrichosis simplex results in progressive hair loss as early as childhood. A team of researchers led by human geneticists from the Bonn University Hospital discovered a gene responsible for this rare form of hair loss. The modifications of the LSS gene result in the degradation of an important enzyme that plays a crucial role in the metabolism of cholesterol. Scientists have presented their findings in the famous newspaper The American Journal of Human Genetics.

The condition is limited to a few hundred families in the world. In early childhood, thin hair tends to sprout sparingly. With age, hair loss progresses. In the end, there are only a few hair left on the head and body. Simple hypotrichosis is a rare form of hair loss (alopecia). Until now, only a few genes causally linked to the disease are known. Under the guidance of the Institute of Human Genetics at the University Hospital Bonn, a team of German and Swiss researchers has deciphered mutations of another gene responsible for hair loss.

The scientists examined the coding genes of three unrelated families of different ancestry. In total, eight members of the family presented the typical symptoms of hair loss. All those affected had mutations in the LSS gene. "This gene codes for lanosterol synthase – LSS for short," said Professor Regina C. Betz of the Institute of Human Genetics at the University Hospital Bonn. "The enzyme plays a key role in the metabolism of cholesterol." However, the blood cholesterol values ​​of the persons concerned are not modified. According to Betz, "There is an alternative metabolic pathway for cholesterol, which plays an important role in the hair follicle and is not related to cholesterol levels in the blood."

The mutation causes the displacement of lanosterol synthase

With the help of tissue samples, the scientists tried to determine exactly where lanosterol synthase was found in the hair follicle cells. The roots of the hair form in the follicle. If the LSS gene is not mutated, the associated enzyme is located in a system of very fine channels in follicular cells, the endoplasmic reticulum. If a mutation is present, lanosterol synthase also spreads outside these channels into the adjacent substance, the cytosol. "We are not yet able to tell why the hair is falling," said lead author Maria-Teresa Romano, a PhD student in Professor Betz's team. "It is likely that the displacement of the LSS from the endoplasmic reticulum will cause a malfunction."

Prof. Matthias Geyer of the Department of Structural Immunology at the University of Bonn examined the consequences of mutations on the structure of the enzyme lanosterol synthase. With him and Professor Betz, there are now two senior researchers from the ImmunoSensation Excellence Group of the University of Bonn, which has been impressively endorsed in the latest cycle of the competition for excellence and who will receive additional funding.

Improved diagnosis

For scientists, the result of the current study is an important discovery: each new decoded gene is an additional element of the puzzle and helps to complete the image of the biological basis of the disease. "A better understanding of the causes of the disease could in the future allow new approaches to the treatment of hair loss," said the geneticist. But there is still a long way to go. However, the discovery of the gene already contributes to improving the diagnosis of the rare disease. Betz: "People with simple hypotrichosis have to do only lose their hair.It is upsetting, but the other organs are not affected."

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More information:
Maria-Teresa Romano et al, Biallelic Mutations in LSS, Lanosterol Synthase Encoding, Inducing Autosomal Recessive Simplex Hypotrichosis, The American Journal of Human Genetics (2018). DOI: 10.1016 / j.ajhg.2018.09.011