A diagnostic concept reaches acceptance through the following four phases: oversight of diagnosis due to ignorance, exposure to a diagnostic concept, overdiagnosis, and appropriate diagnosis. In terms of autism spectrum disorder (ASD), some clinicians are in the phase of oversight, and others are in the phase of overdiagnosis.
 In this case, an uncertain diagnosis was made due to the ignorance of a clinician, and then the diagnosis of ASD was retracted after notification. In other words, this case involved "oversight", "diagnosis", and "retraction of diagnosis" in the 12-year follow-up.
 On considering this case, we reviewed the issues of two conflicting diagnostic procedures: oversight and overdiagnosis. We consider that oversight of diagnosis will result in:
 1) difficulty for people around patients to realize the patients' everyday life difficulties, 2) lowestimation of character and personality by people around the patients, 3) inappropriate support for ASD symptoms provided by people around the patients, and 4) the chronicity, prolongation, and consolidation of symptoms that would otherwise be transient. On the other hand, in overdiagnosis:1)a diagnosis is made based on subclinical symptoms, 2) clinically significant symptoms disappear once psychological stresses are gone, which eventually results in diagnostic error, 3) it is hard for patients to embrace the diagnosis, and 4) patients cannot receive support in spite of the diagnosis.
 Finally, we propose that since the diagnostic boundary of developmental disorders is undermined, the dimensional approach and support are favorable.
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