Information on hypotrichosis - a type of genetic baldness



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Home >> Genetic hair disorders >> Hypotrichosis and its similar types

Hypotrichosis
Hypotrichosis is the term dermatologists use to describe a condition where there has never been any hair growth. This is different from an alopecia. Alopecia describes any condition where there was once hair growth, but there isnít any more. Hypotrichosis describes a situation where there wasnít any hair growth in the first place. The affected area is totally bald and it remains the same for the whole life of the individual.

Hypotrichosis is a condition that affects an individual right from birth and it usually stays with them throughout their lives. Hypotrichosis is generally due to genetic aberrations or defects of embryonic development.

Hereditary issues or genetics also lead to pattern baldness but this is quite different from Hypotrichosis. In pattern baldness the hair remains on the scalp up to puberty. Only after the onset of puberty, due to hormones and other factors, the hair begins to shed off from a particular portion of the scalp.

Also pattern baldness only affects the hair follicles on the scalp whereas, individuals affected with hypotrichosis have many other physical or mental problems beyond their lack of hair. Conditions like Graham-Little syndrome, Ofuji syndrome, cartilage-hair hypoplasia, Jeanselme and Rime hypotrichosis are some of the major conditions where hypotrichosis is a symptom. But more studies are yet needed to be done to understand the mechanism underlying the symptoms.

Studies are also going on to find out how the different genetic defects lead to the formation of bald patches in the scalp. There are also other hair diseases like Alopecia Areata and Seborrheic Dermatitis where hereditary issues play an important role.

Types of Hypotrichosis
There are a few forms of hypotrichosis which are worth mentioning as they are relatively common forms of this hair disorder.
  • Aplasia cutis congenita
  • Triangular alopecia
  • Congenital atrichia
Aplasia cutis congenita.
Aplasia cutis congentia (congenital aplasia) is a developmental defect. Sometimes the skin of the infant in the mother's womb doesn't develop totally. The underlying cause behind this birth defect has yet to be understood.

A baby may be born with a patch of skin that is like an open wound or an ulcer. Often this defect occurs right at the back central portion of the scalp. If the defect is small, the skin will scab over and the baby is left with a scar. This leaves a patch of bald skin devoid of hair follicles.

However, if the defect is large it usually requires an operation. The operation is done to cut out the affected area and close up the skin. This is often done with some urgency as the open wound is a site of potential hemorrhage and infection.

Triangular alopecia.
A similar condition to aplasia cutis congentia is Triangular Alopecia (Alopecia Triangularis). The condition is usually apparent from birth itself. In this hair defect, a triangular patch of skin and hair above the temples is affected. The skin fails to grow hair follicles in this affected area.

The long term result of this hair defect is much same as that of Aplasia cutis congenita. There is a bald patch on the temples where hair does not grow in the whole lifetime. The affected area can be surgically removed or if desired hair transplant can also be done.

Congenital atrichia.
Congenital atrichia or papular atrichia is a hair loss pattern. While congenital atrichia is genetic and runs in families, it is also a gene defect that can spontaneously develop in the embryo during pregnancy though the parents may not have the condition.

Although congenital atricha is considered similar to hypotrichosis, it is not strictly so. People with congenital atrichia can be born with a full head of hair like any normal baby. But in early childhood they lose all their hair, and it never regrows.

Mechanism of congenital atricha
Researchers suggest that baldness due to congenital atricha is related to the blockage of chemical communication between Keratinocytes and dermal papilla cells. Keratinocytes are the cells which form the outer skin epithelium. In a normal scalp, these two cells react with each other and the biochemical signals that they receive from the reaction helps in hair growth and proper functioning of the normal cyclical process.

As the hair follicles enter their first telogen or resting state in early childhood, the two cell types get separated from each other in congenital atrichia. The epithelial cell component of the hair follicle retracts, as it normally does when the hair follicles go into the resting phase of the hair cycle. The dermal papilla cells normally go with the retracting epithelial cells thus keeping close contact which helps in the proper functioning of the hair growth cycles.

But in congenital atrichia the dermal papilla cells are left far behind deep in the skin. The reason behind their remaining in the deep dermis is not known but as they are too far from the epithelial cells there is no communication possible between them. Without this communication, a new anagen growth phase cannot occur and the hair never grows again.

Studies are going on to understand in more detail the mechanism of congenital atricha. There are no baldness treatments for Congenital Atricha or most of the conditions of hypotrichosis as they are due to genetic defects.

However, in recent years clinicians and scientists have been conducting extensive research to understand the hair biology and its related problems. This extensive research will certainly help to understand the various hair formation mechanisms. It will provide a better explanation of the hair problems and may also lead to some baldness treatments that will be able to control the hair loss to an extent.


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