Agraphia (or dysgraphia) is a difficulty writing coherently, if at all, regardless of ability to read. People with dysgraphia often can write, and may even have a higher than average IQ, but lack co-ordination, and may find other fine motor tasks such as tying shoes difficult (It often does not affect all fine motor skills).
They can also lack basic spelling skills (having difficulties with p,q,b,d), and often will write the wrong word when trying to formulate thoughts (on paper). In children, the disorder generally emerges when they are first introduced to writing. They make inappropriately sized and spaced letters, or write wrong or misspelled words despite thorough instruction.
Children with the disorder may have other learning disabilities; however, they usually have no social or other academic problems. Cases of dysgraphia in adults generally occur after some neurological trauma or it might be diagnosed in a person with Autism such as Asperger's or ADHD.