Autism Spectrum Disorder 53
To use the specifier “with or without acco mpanying language impairment,” the cur-
rent level of verbal functioning should be ass essed and described. Ex amples of the specific
descriptions for “with accompanying language impairment” might include no intelligible
speech (nonverbal), single words only, or phrase speech. Language level in individuals
“without accompanying language impairment” might be further described by speaks in
full sentences or has fluent speech. Since receptive language may lag behind expressive
language development in autism spectrum disorder, receptive and expressive language
skills should be considered separately.
The specifier “associated with a known medica l or genetic condition or environmental fac-
tor” should be used when the individual has a known genetic disorder (e.g., Rett syndrome,
Fragile X syndrome, Down syndrome), a medical disorder (e.g. epilepsy), or a history of envi-
ronmental exposure (e.g., valproate, fetal alcohol syndrome, very low birth weight).
Additional neurodevelopmental, mental or be havioral conditions should also be noted
(e.g., attention-deficit/hypera ctivity disorder; developmenta l coordination disorder; dis-
ruptive behavior, impulse-control, or conduct disorders; anxiety, depressive, or bipolar
disorders; tics or Tourette’s disorder; self-inj ury; feeding, eliminatio n, or sleep disorders).
Diagnostic Features
The essential features of autism spectrum diso rder are persistent impairment in reciprocal
social communication and social interaction (Criterion A), and restricted, repetitive pat-
terns of behavior, interests, or activities (Criterion B). These symptoms are present from
early childhood and limit or impair everyday  functioning (Criteria C and D). The stage at
which functional impairment becomes obvious will vary according to characteristics of