Comorbidity.

In Dr. Orzonoff's presentation, she discussed comorbidity, the simultaneous occurrence of two or more clinical diagnoses, as it specifically relates to Autism.  She gave several examples of symptoms and characteristics that ASD shares with other clinical diagnoses and how they may complicate the diagnostic and treatment process. 
Overall, I found the video very interesting and informative.  Many of the characteristics Dr Orzonoff identified as being shared with ASD and other diagnoses are symptoms that I've commonly seen in many of the kids I work with.  For instance, I work with many kids who have severe tantrums, which I often assume are directly related to their ASD diagnosis.  I don't often consider the likelihood that it could it be due to something else such as bipolar disorder.  The video definitely gave me a few things to think about.
I think that in terms of taking into consideration during an FBA, one should keep in mind the point Dr. Orzonoff made about treatments that frequently work for a certain diagnosis NOT working for someone who has said diagnosis.  Orzonoff considers this situation to be indicative of the possibility of comorbidity. 
It's also to be aware of changes in baseline.  In the context of an FBA, the interventionist should be aware of any changes in the observed problem behavior or the onset of new ones before treatment begins.  According to Orzonoff, this is also a sign of comorbidity.
In terms of FBAs, the issue of comorbidity is reason to have a very well-rounded FBA team.  A comorbid diagnosis may result in difficulties that one professional may not be educated or experiened in treating.  In the example of the presentation's case study about the ten year old boy who had asperger's as well as depression, he would likely need a behavior specialist as well as a psychologist.  A behavior analyst who does an assessment and behavior plan for a child on the spectrum is only focusing on behavior and the environmental variables controlling the behavior.  Depression does not fall under the category of an environmental variable because it cannot be objectively observed. 
More importantly, I think the chart that Dr. Orzonoff presented should be used in the diagnosis process.  I think it would help a diagnostician make a parsimonious conclusion about the patient's diagnosis by ruling out the diagnosis of ASD before a unneeded treatment begins.