Subcutaneous fat rapidly disappears completely and the skin becomes thin and brownish with the underlying blood vessels clearly visible. Dental development is also abnormal with delayed shedding of deciduous teeth and early loss of permanent teeth. A severe and painful arthrosis develops, with thickening of the joints leading to impaired mobility. As the children turn old within a remarkably short time, their change in appearance can be shocking. The head is disproportionally large and bald and the facial appearance is one of hollow cheeks with a tight skin, scanty eyebrows and eyelashes, a pointed nose and, frequently, either crowded or missing teeth.
Progeria is extremely rare.
World-wide approximately 36 people are known to have this disease. Following the first description of the disease in 1886, approximately one hundred cases have been registered. The incidence is estimated at 1 in 10,000,000 births for the annual number of new cases, equally spread over all parts of the world and irrespective of race or skin colour. The exact cause of progeria is still unknown. Possibly, it is caused by a genetic defect in the repair of DNA, the genetic material in all living cells, but this has not been proved.