Edison had a learning disability and could not read until the age of 12 years old. He went through life experiencing great difficulty writing; nevertheless, he made some remarkable achievements. These included: the improvement of Bell’s telephone so that it could transmit voice over hundreds of miles instead of the three miles of the prototype; perfection of the automatic stock ticker tape machine; the invention of the cinema projector and the invention of the first practical electric light bulb. He also designed the first system for delivery of electric current to the community through copper wire.
Source: Graham,J., Shinkfield, A., Smith, K. & Polzin, U., 'Employer benefits and costs of employing a person with a disability', Journal of Vocational Rehabilitation, vol. 17, pp. 251-263.