Although it is not necessarily new news that (a) autism rarely exists in some sort of diagnostic vacuum, and (b) that some of the comorbidity 'over-represented' when it comes to autism can actually be more disabling than autism itself, there are still more investigations to be done.
The paper by Vicki Bitsika & Christopher Sharpley  represents an example of how autism science is starting to go past the whole 'is there a connection between...' bit when it comes to autism and various comorbidity, specifically focused on the issue of anxiety. Looking at parental responses on "the Social Responsiveness Scale (SRS) and the GAD subscale of the Child and Adolescent Symptom Inventory (CASI-4 GAD) about their sons" researchers reported some rather interesting trends when it came to the two based on a cohort of young males diagnosed with autism. The authors used the term 'high-functioning' to describe the particular 'type' of autism being looked at in their study but I'm rather less sure this is an appropriate description ('high- and low-functioning' tend to be very generalised terms).
I should back-track slightly and point out that the reasoning behind this research was to "assist in treatment or avoidance of GAD [generalised anxiety disorder] by identifying ASD [autism spectrum disorder]-related behaviours as 'targets' for intervention with anxious children as well as for preventative treatments that could be implemented into daily routines before children become anxious." Of all the debates past and present in relation to autism, specifically on the topic of 'treatment' (or even 'cure'), I don't think anyone would be opposed to the idea that anxiety (whether symptoms or disorder) should be treated and potentially 'cured' in this context. Anxiety can be absolutely disabling including when tied into autism.
Results: bearing in mind their focus on only two parameters (SRS scores and GAD scores) in this study, there are some interesting trends in need of further investigation. So: "For pre-adolescents, high levels of tension in social situations were associated with 3.5-times greater likelihood of having GAD; for adolescents, experiencing difficulty in changes in routine was associated with a 10-fold increase in risk of GAD." The pre-adolescents and adolescents bit in that sentence was due to the division of their cohort on the basis of age. The results suggest therefore that anxiety (or at least GAD) might express itself for various different reasons potentially linked to the age/maturity of the person.
I know some people might be shrugging their shoulders at such a finding and saying 'we already knew that'. Well, I'm not one of them. Take for example the 'change in routines' as being a possible factor in the expression of GAD in adolescents. The recent work by Joyce and colleagues  looking at another important term relevant to this issue - intolerance of uncertainty - adds an additional layer to the Bitsika/Sharpley findings as per their conclusion that: "replicated previous findings based on parent report showing a significant positive relationship between RRB [restricted and repetitive behaviours] and anxiety." RRBs can, amongst other things, include responses to routine (and changes to said routines).
As to the question of what such findings might mean in the context of intervention, the authors talk about how intervening in the symptoms of GAD (a kind of reactionary approach) might also benefit from also trying to focus intervention on certain autistic symptoms too. Outside of the [careful] use of some of the talking/behavioural therapies and perhaps the whiff of some effect from certain pharmacological interventions when it comes to RRBs and autism, there isn't a great deal on offer at the moment in autism science and practice in this area. Indeed, if the relationship between RRBs and anxiety is further confirmed (and I mean confirmed ), I'd perhaps suggest that moves to target RRBs in the context of autism could/should be a research priority if only to potentially reduce the effects of anxiety.
And the inquiry continues ...
 Bitsika V. & Sharpley CF. The association between parents' ratings of ASD symptoms and anxiety in a sample of high-functioning boys and adolescents with Autism Spectrum Disorder. Res Dev Disabil. 2017 Mar 1;63:38-45.
 Joyce C. et al. Anxiety, Intolerance of Uncertainty and Restricted and Repetitive Behaviour: Insights Directly from Young People with ASD. J Autism Dev Disord. 2017 Feb 25.
 Wang S. et al. Sex Differences in Diagnosis and Clinical Phenotypes of Chinese Children with Autism Spectrum Disorder. Neurosci Bull. 2017 Feb 25.
 South M. et al. Symptom overlap on the srs-2 adult self-report between adults with asd and adults with high anxiety. Autism Res. 2017. March 7.
Bitsika, V., & Sharpley, C. (2017). The association between parents’ ratings of ASD symptoms and anxiety in a sample of high-functioning boys and adolescents with Autism Spectrum Disorder Research in Developmental Disabilities, 63, 38-45 DOI: 10.1016/j.ridd.2017.02.010