“Autism Cluster” Sparks Renewed Questions in the Role of Genetics in ASD

The discovery of a cluster of 12 genetically related children diagnosed with autism has renewed questions into the role DNA plays in causing autism spectrum disorder, or ASD. The children in question are all related through a common sperm donor that provided reproductive material to numerous sperm banks, resulting in an unprecedented “autism cluster” of children.

The connection between these children who live in various locations across the United States, Canada, and Europe; was made when Danielle Rizzo’s sons, both conceived via in vitro fertilization, were diagnosed with autism. Connecting with other parents through social media, Rizzo found that at least twelve children conceived using sperm from a common donor, known only as “Donor H898”, were all diagnosed as being somewhere on the autism spectrum, with many having  secondary diagnoses of ADHD, dyslexia, mood affective disorders, epilepsy, and other developmental challenges.

A clustering effect of this sort is also virtually unheard of: according to a genetics councilor she spoke with, Rizzo was told that the odds of so many blood-related children with autism occurring spontaneously was akin to all the mothers “opening up a dictionary and pointing to the same letter of the same word on the same page at the same time.” The uniqueness of this case has garnered the attention of some of the world’s foremost experts in the genetics of autism, who have been gathering genetic samples from the families involved.

More than 100 genes have been identified that appear to be linked to autism, a condition that affects 1 in 59 children in the United States. But while having these genes doesn’t guarantee that one will develop ASD, they do appear to increase the odds of an individual becoming autistic. According to Doctor Stephen Scherer, who conducts research into the genetics of ASD at Toronto’s Hospital for Sick Children, there appears to be a subset of what he calls “high impact” genes that are estimated to be involved in 5 to 20 percent of all autism cases.

In the case of Rizzo’s sons, they do have genetic mutations that are associated with ASD: the older son has mutations in his MBD1 and SHANK1 genes, and the younger with the MBD1 variant. Upon investigating Donor H898’s background, Rizzo found that the individual had extensively falsified his profile with the sperm bank, having not only been diagnosed with ADHD, but also that he “went to a school for children with learning and emotional disabilities.” H898 had instead simply put “NA” on over 100 medical questions, including those involving mental health issues, on his profile.

But does this mean that we can blame our genetics when a child develops ASD? It turns out that the answer isn’t nearly that simple.

“We call autism one thing, but it’s different in every person,” explains Dr. Wendy Chung, a professor of pediatric medicine at Columbia University. “In some, it’s all about the genes. Some it’s a combination of genes and the environment. Some people, it’s unknown.”