Background: While autism spectrum disorder (ASD) is generally thought of as distinct from other neuropsychiatric disorders such as schizophrenia or attention deficit-hyperactivity disorder (ADHD), the actual symptoms of ASD can show remarkable overlap with those of individuals with schizophrenia or ADHD.  Likewise, genetics studies have shown that there is a significant degree of genetic overlap between ASD and other psychiatric disorders, with rare and common genetic variants affecting many of the same genes in individuals with these disorders.

What’s New: A new study published online, February 28, 2013, in The Lancet reports that patients diagnosed with one of five psychiatric disorders, including ASD, schizophrenia, bipolar disorder, ADHD, and major depressive disorder, share common variations along four spots in their DNA. While two of the locations have unknown functions, the other two are found in genes that code for subunits of ion channels that, when activated, open and allow calcium ions to enter into neurons.  One of these genes, CACNA1C, is responsible for Timothy syndrome, in which as many as 80% of affected individuals are also diagnosed with ASD.

Why it’s Important: The findings of this study suggest that specific common genetic variants, in particular those variants in genes that encode for calcium channel subunits and other brain-expressed genes, can act as shared genetic risk factors for not only ASD, but other psychiatric disorders as well.  These results also help to explain the sometimes-blurred boundaries between ASD and other psychiatric disorders. According to the present study, drugs that affect calcium channel signaling may offer a promising therapy for these disorders, although additional studies are required to test safety and efficacy.

Genetics

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