Information on hypertrichosis and excessive hair growth
Information on hypertrichosis and hair removal treatments
Congenital Hypertrichosis Lanuginosa (CHL)
Hypertrichosis is an excessive hair growth disorder that refers only to hair length and density, which is more than the accepted normal limits for the age, sex and racial group of the patient and does not imply any particular hair distribution. It is not androgen related.
One category of hypertrichosis is called generalized congenital hypertrichosis. Congenital Hypertrichosis Lanuginosa (CHL) comes under this category.
CHL, a rare inherited disorder, is a truly generalized and confluent hypertrichosis with a different hair growth pattern. At birth, the entire body of the newborn except the hands and feet are covered with excess fine blond hairs. Lanugo hairs are normally shed in the seventh or eighth month of pregnancy or in the first few months after birth. In CHL, lanugo hairs remain after birth or may develop later in infancy. It is not definite that these are lanugo hairs. They could be vellus since in very few cases was any microscopic examination done.
CHL cases are known to persist, resolve or increase with age. In most cases of CHL, hair shedding begins from the trunk during the first year of life and later spreads to the limbs, but some excess hair is retained throughout life. It is unclear why in some patients there is no resolution of CHL. Opinion is divided on whether in such cases the expression of CHL is different or whether it is an entirely different syndrome. CHL can be inherited as an autosomal trait but there are exceptions to it. Many authors have reported abnormalities of chromosome 8q in CHL. The incidence of CHL is estimated at one in a billion.
Most cases of CHL are otherwise normal except for dental eruptions. This condition has been categorized as a form of tricho-odonto-ectodermal dysplasia. Cases of CHL with photophobia, infantile genitalia, and growth and mental retardation have also come to light.
Sub-types of Congenital Hypertrichosis Lanuginosa
CHL has been categorized into various subtypes. These include:
- Ambras syndrome
Ambras syndrome: Ambras syndrome also called hypertrichosis universalis congenital shows persistent hairs 4 inches to 10 inches long. The growth is more prominent and the hair darker on the shoulders and the face. The face includes the nose. In some cases Ambras syndrome is inherited as Ambras syndrome with cytogenic abnormalities.
Congenital generalized hypertrichosis: This type of CHL probably has an X- linked dominant form of inheritance and was first found in a Mexican family. The hair here is curly and shorter than in Ambras syndrome. The disorder affects males more severely than females who have a patchy growth. The gene for this disorder has reportedly been located on a type of X-chromosome.
Hypertrichosi terminalis, generalized, with gingival hyperplasia: Hereditary gingival fibromatosis or hyperplasia associated with hypertrichosis is the cause of this disorder. It actually mimics CHL and is not classified as such, except wrongly. It is a rare disorder occurring in 1 out of 175,000. It is usually autosomal dominant.
Gingival fibromatosis appears and develops only when primary or secondary teeth have emerged. These teeth are buried in its hypertrophying redundant tissue. When the disorder is associated with hypertrichosis, gingival fibromatosis is almost always present at birth or develops in the first year of life, though it can appear as late as puberty. Excessive hair growth is not as severe as in CHL and appears mainly on the eyebrows, face, limbs and mid-back.
Ramon syndrome: The Ramon syndrome, an autosomal recessive inherited condition, is characterized by gingival fibromatosis, mental retardation, epilepsy, cherubism and stunted growth with or without juvenile rheumatoid arthritis. The hypertrichosis is moderate and inconstantly associated.
Brachmann-de Lange syndrome: CHL, although easily identifiable in its fully developed state, may be difficult to distinguish in infancy from hypertrichosis cases which are generalized but not necessarily confluent. Brachmann-de Lange syndrome is one example of such hypertrichosis.
The hypertrichosis is nowhere as generalized or confluent as CHL but in infancy there might be some overlap of excess hair growth. The infants affected by Brachmann-de Lange syndrome can be easily recognized because of their highly characteristic and persistent features. The features include distinctive faces, secondary to a low hairline, penciled but not bushy eyebrows, long eyelashes and thin lips. They also have relatively constant abnormalities like mental and growth retardation. Excess and persistent lanugo hairs occur at birth or infancy on the forehead, lateral face, back, shoulders and extremities.
This syndrome is usually sporadic but may be a genetic disorder with autosomal dominant inheritance.