Behavioural phenotypes of autism in autistic and nonautistic gender clinic-referred youth and their caregivers.

In recent years, referrals of youth to specialised gender services have risen sharply, with ~11% of these youth diagnosed as autistic compared with a general population rate of ~1%. In two preregistered studies, we addressed this insufficiently understood intersection. In Study 1, we examined the number and developmental trajectory of autism traits in autistic and nonautistic gender clinic-referred and cisgender youth (aged 7-16 years) using both screening measures (Autism-Spectrum Quotient Children's Version and Autism-Spectrum Quotient Adolescent Version, Social Communication Questionnaire-Lifetime) and diagnostic tools (Autism Diagnostic Interview-Revised, Brief Observation of Symptoms of Autism). In Study 2, we examined autism traits among the caregivers of participants from each group using the Autism-Spectrum Quotient Adolescent Version. Study 1 results showed the autism phenotype in autistic gender clinic-referred youth closely resembled that of their cisgender autistic peers. In addition, after addressing methodological limitations in previous research, we found no evidence of elevated autism traits in nonautistic gender clinic-referred youth, challenging findings of some earlier studies. Study 2 provided evidence of familial aggregation of both autism traits and diagnoses among caregivers of both autistic gender clinic-referred and cisgender participants. Taken together, these findings challenge the hypothesis that autism in gender-diverse youth is merely a 'phenomimic' of autism and provide valuable clinical insights into the presentation of autism in this population.Lay abstractIn recent years, more young people have been referred to specialised gender clinics for support with their gender identity. Interestingly, about 11% of these young people are also diagnosed with autism-much higher than the general population rate of only around 1%. This overlap has raised important questions about how autism and gender diversity are related, and even whether autism traits in gender-diverse people with an autism diagnosis really reflect autism. In this research, we carried out two studies to understand this link better. In the first study, we looked at autism traits in gender-diverse children and adolescents aged 7-16 years who were referred to a gender clinic for issues with their gender identity. We compared them with both autistic and nonautistic children who were not referred to gender services. We used several standard tools to assess autism-related traits, including both questionnaires and clinical interviews. We found that gender-diverse youth who were also autistic showed similar patterns of autism traits as cisgender autistic children who were not exploring their gender. Importantly, nonautistic gender-diverse youth did not show unusually high levels of autism traits, which challenges some earlier studies that suggested they might. In the second study, we explored autism traits in the caregivers (mostly mothers) of the young people in our first study. We found that caregivers of autistic children-whether the children were gender-diverse or not-were more likely to be autistic than the caregivers of nonautistic children. Moreover, even