I will believe this study once they do smaller studies that replicate the data. They should be able to look at each individual group (ADHD, Bipolar, Schizophrenia, Autism) and find a significant difference from the control group based on the pathways they have identified. (Differences in the calcium ion channels and whatever else they found)

It wasn't about this study. I've mentioned something like this at one point or another.

Also, this study doesn't link major depression to the other 4. It also doesn't make the claim that these genes are heritable.

Plus you have to remember that this is a casual study. Causation doesn't prove anything. In the first sentence they said 'may'! Replication will tell us if their findings are valid. If this study produces accurate work it means treatment will get better because they can find medication that directly affects the ion channels that they identified.