<unk>  is a communication disorder in which there are difficulties with verbal and written expression. It is a specific language impairment characterized by an ability to use expressive spoken language that is markedly below the appropriate level for the mental age, but with a language comprehension that is within normal limits. There can be problems with vocabulary, producing complex sentences, and remembering words, and there may or may not be abnormalities in articulation. Careful diagnosis is also important because "atypical language development can be a secondary characteristic of other physical and developmental problems that may first manifest as language problems".
Expressive language disorder
Developmental language disorder
Mixed receptive-expressive language disorder
Nonverbal autism
Pervasive developmental disorder
Developmental disability
Low-functioning autism
Multiple complex developmental disorder