First from Journal of the American Academy of Child & Adolescent Psychiatry, November 2018. The lead investigator is Jack L. Turban at Harvard. Emphasis added:
The topic of gender identity in children and adolescents has gained widespread attention in Western society during the past decade … More recently, growing attention has been paid to a putative relation between gender dysphoria (GD) and autism spectrum disorder (ASD). This concept has become particularly popular in the lay press. Some individuals have gone so far as to suggest that transgender identity is a result of underlying psychopathology, with ASD being one example. These conclusions are not supported by extant research, and practicing child and adolescent psychiatrists should be aware of the literature on this topic and its limitations.
Note that Turban is dismissing “underlying psychopathology” including ASD.
Dr. Anna I.R. van der Miesen (Department of Child and Adolescent Psychiatry, Center of Expertise on Gender Dysphoria, VU University Medical Center, The Netherlands) et al have a more nuanced take. Again, emphasis added:
In their Translations article in the January issue of the Journal, Turban and van Schalkwyk provide a critical evaluation of the recently published literature on co-occurring gender dysphoria (GD) and autism spectrum disorder (ASD). … Given the low-grade evidence in this field for most clinical recommendations, good-quality research is of great relevance. We support the debate on the GD-ASD literature and acknowledge that translations of the findings to the lay press such as “Do transgender children just have autism?” are not helpful. Also, we agree with many of the limitations brought forward by the authors and acknowledge that, at present, sound underlying evidence for a GD−ASD link is lacking. However, we believe that some nuance in argumentation could help forward the debate of this clinically important topic.
In other words, given the existing evidence there is no link but additional research in this area is worthwhile.
Turban and van der Miesen are leading experts in juvenile gender dysphoria. You may recall that Jack Turban went to war with Michelle Cretella over her misleading BS.