Hypertrichosis (also called Ambras Syndrome or werewolf syndrome) is an abnormal amount of hair growth on the body. There are two distinct types of hypertrichosis: generalized hypertrichosis, which occurs over the entire body, and localized hypertrichosis and hirsutism, which are restricted to a certain area. 


The excess growth of hair occurs in areas of the skin with the exception of androgen-dependent hair of the pubic area, face, palms and soles of the feet and axillary regions. The density of the hairs per square centimeter, the thickness of the hairs, color of the hairs, speed of hair growth, and qualities such as kinkiness tend to vary from one part of the body to another and also from one person to another


Hypertrichosis can be either congenital (present at birth), caused by genetic mutations or acquired later in life and may be caused by cancer.

Congenital generalized hypertrichosis terminalis is thought to be caused by genetic changes on chromosome 17 resulting in the addition or removal of millions of nucleotides. A female carrying the hypertrichosis gene has a 50% chance of passing it to her offspring. A male carrier will pass this form of hypertrichosis to his daughters, but never the sons.

Congenital forms of hypertrichosis are rare. Only 50 cases of congenital hypertrichosis lanuginosa have been recorded since the Middle Ages, and fewer than 100 cases of congenital generalized hypertrichosis have been documented in scientific publications and by the media. Congenital generalized hypertrichosis is isolated to one family in Mexico.[ Acquired hypertrichosis and hirsutism are more common.

Famous specimen

People with hypertrichosis often found jobs as circus performers due to their unique appearance. Fedor Jeftichew ("Jo-Jo the Dog-Faced Man"), Stephan Bibrowski ("Lionel the Lion-Faced Man"), Jesus "Chuy" Aceves ("Wolfman"), Julia Pastrana and Annie Jones ("the bearded woman"), all had hypertrichosis.

In 2011, Supatra Sasuphan, an 11-year old girl from Thailand with hypertrichosis was named the world’s hairiest girl by the Guinness Book of World Records.

In 1826, John Crawford was leading a mission for the Governor-General of India through Burma. He tells of meeting a hairy man, Shwe-Maong. Shwe-Maong lived in the court of King Ava and acted as an entertainer. Shwe-Maong had four children: three normal children, and one child with congenital hypertrichosis, named Maphoon. On a second mission to Ava, Maphoon was described as a thirty year old woman with two sons, one of which had hypertrichosis.The affected son was named Maong-Phoset. He had an affected daughter named Mah-Me. Whereas all affected members of the family had dental problems, the unaffected members had perfect teeth.