In the United States, about 1 in 3,500 people have NF1 and 1 in 25,000 have NF2. Males and females are affected equally often. In NF1, symptoms are often present at birth or develop before 10 years of age. While the condition typically worsens with time, most people with NF1 have a normal life expectancy. In NF2, symptoms may not become apparent until early adulthood. NF2 increases the risk of early death. Descriptions of the condition occur as far back as the 1st century. It was formally described by Friedrich Daniel von Recklinghausen in 1882, after whom it was previously named.