23andMe Autism: Understanding DTC DNA Testing for Autism

Autism Spectrum Disorder (ASD) is a complex developmental condition that involves persistent challenges in social interaction, speech and nonverbal communication, and restricted/repetitive behaviors.

The complexity and broad spectrum of autism make its genetic underpinnings equally complex.

Given the interest in understanding the genetic factors influencing ASD, it’s natural to question if a direct-to-consumer (DTC) genetic testing service like 23andMe can detect autism.

23andMe Autism and 50 more health condition

The Genetics of Autism

Autism is thought to have a strong genetic basis, as suggested by twin and family studies.

However, it’s important to understand that ASD is a highly complex condition with multifactorial roots, including both genetic and environmental factors.

More than 100 genes have been implicated in autism, with each genetic variant only contributing a small part to the risk of developing ASD.

Some of these genetic factors are inherited, while others are the result of new (de novo) mutations in the individual.

Numerous genes have been implicated in ASD, although each typically contributes only a small part to the overall risk.

This is a theoretical example and not an exhaustive list of all the SNPs associated with ASD.

Gene	SNP ID	Variant	Risk Allele	Impact
SHANK3	rs9616915	C/T	T	Associated with ASD
SYNGAP1	rs2274736	A/G	A	Associated with ASD
CNTNAP2	rs7794745	A/C	C	Associated with ASD
NLGN3	rs11795613	A/G	G	Associated with ASD
NLGN4	rs3747333	C/T	T	Associated with ASD
NRXN1	rs2192206	C/T	T	Associated with ASD
FMR1	rs28900371	C/G	G	Associated with Fragile X Syndrome and ASD
MECP2	rs28934904	G/A	A	Associated with Rett Syndrome and ASD
TSC1	rs78492931	T/C	C	Associated with Tuberous Sclerosis and ASD
TSC2	rs8042919	C/T	T	Associated with Tuberous Sclerosis and ASD

Note: This table is illustrative and not exhaustive. The associations listed here are oversimplifications; in reality, the relationship between these SNPs and ASD is typically more complex and may depend on other factors, including other genetic and environmental factors. Please consult with a healthcare provider or a genetic counselor for personalized advice.

The following are some examples of genes that have been associated with ASD in various studies:

SHANK3 (SH3 and multiple ankyrin repeat domains 3):

Mutations in this gene, which is involved in the formation and function of synapses (the junctions where nerve cells communicate), can lead to Phelan-McDermid syndrome, a disorder that often includes ASD-like symptoms.

SYNGAP1 (synaptic Ras GTPase activating protein 1

Mutations in this gene can disrupt normal synaptic function, leading to intellectual disability and ASD.

CNTNAP2 (contactin associated protein-like 2)

Variations in this gene, which is involved in the development of neural connections, have been associated with an increased risk of ASD.

NLGN3 and NLGN4 (Neuroligin 3 and 4)

Mutations in these genes, which encode proteins involved in synapse function, have been found in some people with ASD.

NRXN1 (Neurexin 1):

Deletions of genetic material from a specific region of this gene have been associated with ASD. Neurexins, the proteins encoded by NRXN genes, are involved in the formation and function of synapses.

FMR1 (Fragile X mental retardation 1)

Mutations in this gene can cause Fragile X syndrome, an inherited form of intellectual disability that is often accompanied by ASD.

MECP2 (methyl CpG binding protein 2)

Mutations in this gene lead to Rett syndrome, a disorder that predominantly affects girls and can include symptoms of ASD.

TSC1 and TSC2 (Tuberous Sclerosis Complex genes)

Mutations in these genes cause tuberous sclerosis, a condition that often includes symptoms of ASD.

This is just a sample of the many genes that have been associated with ASD, and ongoing research continues to identify more genes involved.

Importantly, having a variant in any of these genes does not necessarily mean that an individual will develop ASD; these are risk factors, not deterministic factors.

Genetic susceptibility interacts with environmental influences to ultimately determine whether a person develops ASD.

It’s also critical to understand that carrying these genetic variants does not guarantee an individual will develop autism.

Many people carry these variants without developing ASD, suggesting that other genetic and environmental factors are at play.

23andMe Autism Reports

23andMe currently does not offer a test for autism.

There are a few reasons for this:

The complexity of Autism Genetics

As mentioned earlier, autism is linked to many different genes, and the interplay between these genes and environmental factors is not fully understood.

A simple positive or negative result would not accurately represent this complexity.

Ethical and Psychological Considerations

Even if a reliable genetic test for autism was available, there would be significant ethical and psychological considerations involved in delivering such results.

Without a clear course of action for those found to be at an increased genetic risk, the information may cause undue stress or confusion.

Regulatory Approval

In the United States, the FDA regulates genetic tests that provide health-related information.

Given the current state of scientific understanding and the ethical concerns mentioned above, it is unlikely that a test for autism risk would gain FDA approval in the near future.

Genetic Testing for Autism

While 23andMe does not offer a test for autism, genetic testing can sometimes be helpful in a clinical setting.

For individuals who have already been diagnosed with ASD, certain genetic tests can sometimes identify a specific genetic syndrome as the cause.

This can help in understanding the condition better and in some cases, can guide treatment.

However, these tests are typically conducted under the guidance of a medical professional or genetic counselor, who can provide important context for the results.

Conclusion

While 23andMe offers a range of genetic tests, it currently does not offer a test that can detect or predict the risk of autism due to the complex nature of ASD.

Autism involves the interplay of multiple genetic and environmental factors, many of which are still being researched.

Any questions or concerns about autism risk should be discussed with healthcare professionals who can provide the most relevant and up-to-date information.

References

Modabbernia A, Velthorst E, Reichenberg A. Environmental risk factors for autism: an evidence-based review of systematic reviews and meta-analyses. Mol Autism. 2017;8:13. Published 2017 Mar 17. doi:10.1186/s13229-017-0121-4
Gaugler T, Klei L, Sanders SJ, et al. Most genetic risk for autism resides with common variation. Nat Genet. 2014;46(8):881-885. doi:10.1038/ng.3039
Schaefer GB, Mendelsohn NJ; Professional Practice and Guidelines Committee. Clinical genetics evaluation in identifying the etiology of autism spectrum disorders: 2013 guideline revisions. Genet Med. 2013;15(5):399-407. doi:10.1038/gim.2013.32
U.S. Food and Drug Administration, 23andMe, Inc. 11/22/2013 – Warning Letter.
Leblond CS, Nava C, Polge A, et al. Meta-analysis of SHANK Mutations in Autism Spectrum Disorders: a gradient of severity in cognitive impairments. PLoS Genet. 2014;10(9):e1004580. Published 2014 Sep 25. doi:10.1371/journal.pgen.1004580
Berryer MH, Hamdan FF, Klitten LL, et al. Mutations in SYNGAP1 cause intellectual disability, autism, and a specific form of epilepsy by inducing haploinsufficiency. Hum Mutat. 2013;34(2):385-394. doi:10.1002/humu.22248
Alarcón M, Abrahams BS, Stone JL, et al. Linkage, association, and gene-expression analyses identify CNTNAP2 as an autism-susceptibility gene. Am J Hum Genet. 2008;82(1):150-159. doi:10.1016/j.ajhg.2007.09.005
Jamain S, Quach H, Betancur C, et al. Mutations of the X-linked genes encoding neuroligins NLGN3 and NLGN4