Hypotrichosis simplex is a progressive, rare form of hair loss
which involves the hair shaft becoming increasingly thinner. It tends to start in early childhood and worsen with age.
There are three forms of hypotrichosis simplex; one is confined to causing diffuse hair thinning to the scalp only, whilst another other also affects all body hair. The third form, known as the Marie Unna type, is less seen and involves a twisting hair dystrophy.
The appearance of thinning hair in these instances is similar to that found in cases of genetic hair loss - Male Pattern Baldness
and Female Pattern Hair Loss
- and is also hereditary, so genetics are still very much involved.
To this end, according to research published in the American Journal of Human Genetics
, a new gene responsible for hypotrichosis simplex
has been discovered by researchers in Germany.
Prof. Dr. Regina C. Betz from the team of German and Swiss researchers at the University Hospital of Bonn's Institute of Human Genetics, which has been investigating the cause of hypotrichosis simplex by studying affected families, explained the new gene development.
"This gene encodes lanosterol synthase -- LSS for short. The enzyme plays a key role in cholesterol metabolism. There is an alternative metabolic pathway for cholesterol, which plays an important role in the hair follicle and is not related to blood cholesterol levels.
Cholesterol blood values remain unaffected by this in those with the condition.
"We are not yet able to say why the hair is falling out,"
lead study author Maria-Teresa Romano, a doctoral student in Prof. Betz's team, told Science Daily. "It is likely that the displacement of LSS from the endoplasmic reticulum results in a malfunction."
Previously, according to information from the US Department of Health & Human Services' Genetic and Rare Diseases Information Centre, hypotrichosis simplex was only thought to occur as a result of inheriting it as either an autosomal dominant or autosomal recessive trait, or where there are mutations in the APCDD1 gene on chromosome 18p11.
Help understanding of pattern hair loss
The University Hospital of Bonn team states that relatively little is known about controlling hair growth
on a molecular level, but is optimistic that this new discovery will benefit not only those investigating hypotrichosis simplex, but also genetic hair loss
, as well as potentially furthering our understanding of hair growth in general.
The team's findings state: 'Investigation of genetic conditions in individuals with isolated alopecia offers the unique possibility to identify factors that are not only necessary but also specific for hair growth. HSS [hypotrichosis simplex], with no involvement of body hair, eyebrows, and eyelashes, may be particularly important for our understanding of the genetic, molecular, and cellular pathways that regulate growth of scalp hair. Interestingly, the histological picture of scalp biopsies from patients with HSS has many features of androgenetic alopecia, such as miniaturized follicles of the vellus type
and absence of scarring (Ibsen et al. 1991). Ultimately, the identification of the mutated gene could illuminate our understanding of common androgenetic alopecia.'
Although there are clinically-proven, MHRA licensed and FDA approved hair loss treatments
for male and female pattern baldness, there are currently no options for treating hypotrichosis simplex. However, with every new development - like this latest gene discovery - scientists get closer to understanding how one may be developed.