This article is in Japanese, so I have only seen the abstract.
In the abstract, the authors suggest that people with autism spectrum disorders (ASD) “often have identity crises which sometimes include gender dysphoria.” They speculate that when people with ASD become teenagers, they “realize their uniqueness and differences compared to others, and, as a result, they may develop confusion of identity which could be exhibited as gender identity disorder.”
They talk about a recent study that found that “amongst 204 children and adolescents who visited a GID clinic in the Netherlands, 7.8% were diagnosed with autism spectrum disorders after a careful diagnostic procedure by a multi-disciplinary team.”
The paper looks at four cases of young people with both ASD and either gender dysphoria or “related symptoms.” Their study included:
“1) a girl with PDD (pervasive developmental disorders=autism/ASD) who repeatedly asserted gender identity disorder (GID) symptoms in response to social isolation at school,
2) a junior high school boy with PDD and transvestism,
3) a boy diagnosed with Asperger’s disorder who developed a disturbance of sexual orientation, and
4) a boy with Asperger’s disorder and comorbid childhood GID.”
They believe that “Many of the clinical symptoms related to gender dysphoria might be explained by the cognitive characteristics and psychopathology of PDD.”
Without seeing more, it is hard to evaluate this study.
Nevertheless, they do not seem to have proven their case very well. Two of the four people they discuss do not sound like they have gender dysphoria.
For the other two children, it would help to know more details – did they outgrow the gender dysphoria? do they now believe that they were wrong about their gender? could they have gender dysphoria and ASD?
The authors conclude by saying that gender dysphoria has become more well-known in Japan and they are seeing more patients complaining of it.
They believe that it is important to consider an underlying diagnosis of ASD for patients with gender dysphoria; I can agree with that conclusion at least.