Language disorders occurring with these conditions need to be assessed and children offered appropriate intervention, but a terminological distinction is made so that these cases would be diagnosed as language disorder associated with the main diagnosis being specified: e.g. "language disorder associated with autism spectrum disorder." The reasoning behind these diagnostic distinctions is discussed further by Bishop (2017). Benchmarks for children with developmental language disorder
Common red flags at one year of age:  

No reaction to sound
No babbling
Difficulty feeding
No imitation
Limited use of gesturesAt two years of age:

Makes minimal attempts to communicate with gestures or words
Has not spoken their first words
Difficulty following simple directions
Inconsistent response to "no"At three years of age:

Limited use of speech
Incomprehensible speech
Limited understanding of simple questions
Difficulty naming objects
Frustration related to communicationAt four years of age:

Uses only 3-word phrases
Speech is not understandable to parents
Takes a long time to understand others
Difficulty asking questions and finding words to express thoughtsAt five years of age:

Speaks only in simple sentences
Speech is not understandable to teachers
Difficulty answering questions
Difficulty with complex directions
Difficulty telling stories
Difficulty with peer interactions

Assessment
Assessment will usually include an interview with the childs caregiver, observation of the child in an unstructured setting, a hearing test, and standardized tests of language. There is a wide range of language assessments in English. Some are restricted for use by experts in speech-language pathology: speech and language therapists (SaLTs/SLTs) in the UK, speech-language pathologists (SLPs) in the US and Australia. A commonly used test battery for diagnosis of DLD is the Clinical Evaluation of Language Fundamentals (CELF).
Developmental language disorder (DLD) is identified when a child has problems with language development that continue into school age and beyond. The language problems have a significant impact on everyday social interactions or educational progress, and occur in the absence of autism spectrum disorder, intellectual disability or a known biomedical condition. The most obvious problems are difficulties in using words and sentences to express meanings, but for many children, understanding of language (receptive language) is also a challenge. This may not be evident unless the child is given a formal assessment. Classification
Terminology
The term developmental language disorder (DLD) was endorsed in a consensus study involving a panel of experts (CATALISE Consortium) in 2017. The study was conducted in response to concerns that a wide range of terminology was used in this area, with the consequence that there was poor communication, lack of public recognition, and in some cases children were denied access to services. Developmental language disorder is a subset of language disorder, which is itself a subset of the broader category of speech, language and communication needs (SLCN). The terminology for childrens language disorders has been extremely wide-ranging and confusing, with many labels that have overlapping but not necessarily identical meanings. In part this confusion reflected uncertainty about the boundaries of DLD, and the existence of different subtypes. Historically, the terms "developmental dysphasia" or "developmental aphasia" were used to describe children with the clinical picture of DLD. These terms have, however, largely been abandoned, as they suggest parallels with adult-acquired aphasia.