Could they have missed an ASD?

What condition are you referring to as ASD? ASD could be Atrial septal defect or it could be Autism Spectrum Disorder. If it is the former, you should definitely get a 2nd opinion, as heart problems are often missed. If it is the latter, the test was designed by psychologist Simon Cohen at Cambridge's Autism Research Centre. In the first major trial using the test, the average score in the control group was 16.4. Eighty percent of those diagnosed with autism or a related disorder scored 32 or higher. It should be noted that the test is not a means for making a diagnosis, and many who score above 32 and even meet the diagnostic criteria for mild autism or Asperger's report no difficulty functioning in their everyday lives.