The cause of this condition is unknown, but it is thought that it might be caused by elevated levels of the female sex hormone oestrogen.

BBC: Surgery

Details of his condition are still unknown.

ECONOMIST: The political implications of a cancer diagnosis

The condition of the IFOR personnel was unknown.

CNN: NATO heads for Bosnia's front lines

China Central Television and other major media say four new people living in different cities in Jiangsu province are in critical condition with H7N9, a strain of bird flu that was previously unknown in humans.

BBC: China media: Concerns over bird flu

On a global scale, however, autism rates are largely unknown, because of a lack of research and reliable epidemiological studies and a relative lack of awareness surrounding the condition, Dawson told CNN.

CNN: Autism efforts go global at U.N. forum