Autism spectrum disorders (ASD) are diagnosed or begin to be symptomatic in infancy or early childhood, and persist through adulthood. ASD tends to affect communication, social interaction, and certain behavioral patterns.
While autism is oftentimes accompanied by, and can sometimes be mistaken for, other conditions and diseases, autism spectrum disorder symptoms can also be closely associated with certain rare diseases.
What rare diseases and disorders are comorbid with autism?
Comorbidity simply refers to more than one condition occurring in the same person at the same time. Quite a few rather rare conditions and diseases tend to exist in comorbidity with ASD, including tuberous sclerosis complex, Timothy Syndrome, and Fragile X, as well as less rare diseases such as epilepsy.
In the case of genetic disorders and rare diseases that are comorbid with autism spectrum disorders and their related symptoms, there may be similar or identical genetic and biological causes, in some cases a missed or duplicated gene or chromosome.
For example, a recent study revealed that the brains of people with autism contain similar gene-expression patterns to those of people with schizophrenia or bipolar disorders. Certain traits and genetic variants such as language difficulties or aggressive behaviors may show up across both types of conditions. And, schizophrenia and bipolar disorders may be comorbid with autism as well as associated conditions.
Another related comorbidity pattern shows that the incidence of epilepsy in people with autism is 1 in 3, and, vice versa, people who have epilepsy are 8 times more likely to have autism. There may be a partial genetic connection, or it may be that early seizures open the door to some features of autism. Epilepsy is a common enough disorder that it is relatively easy to both connect it with an incidence of autism and to separate from it. However, some disorders and their symptoms cannot be easily distinguished from autism (ASD), although they are different.
Aside from rare or severe diseases comorbid with autism symptoms, there are the more common physical and mental health conditions that may not immediately seem related to autism, but in fact appear alongside it very frequently. Medical problems can include sleep disorders, gastrointestinal issues, and seizures. Mental health comorbid conditions often include ADHD (attention deficit hyperactivity disorder), depression, anxiety, and OCD (obsessive-compulsive disorder).
Intellectual disability and autism
Most genes that have been identified as autism genes can also cause what is now termed intellectual disability. This was once known as mental retardation, a term that is no longer used as it has come to be considered derogatory. The causative genes are the same, but the resulting conditions are not identical. Attitudes toward autism have changed drastically as well, with a better understanding of what autism is, and how it is distinguished from intellectual disability. Autism and intellectual disability can sometimes appear together, but they should not be mistaken for each other.
Dual diagnosis of autism plus intellectual disability has declined. In the 1980s, up to 69% of autism diagnoses were also diagnosed with mental retardation. Unfortunately, medical professionals still sometimes mistake one condition for the other, despite narrowed and more defined diagnostic criteria for autism. Other things that can influence and distort proper evaluation and the distinction between autism and rare chromosomal diseases can share some symptoms: age, race, sex, and intelligence, or rather tested intelligence quotient (IQ). For example, female children and adults are less likely to receive an autism diagnosis, while autistic black children are more likely to be diagnosed as intellectually disabled rather than autistic, in contrast to autistic white children who receive a diagnosis of autism.
Clearer diagnoses would open up new paths to the correct services for people who have been diagnosed incorrectly. Autism and intellectual disability may share some genetic bases, but of course, they need to be understood and treated differently. And for children who have one but not the other, or who have both, this would lead them to services that are more appropriate for them and their needs.
Rare disease with autism symptoms
- DEAF1-related disorders: neurologic diseases that often feature intellectual disability, speech difficulties, and motor developmental delay. Additional features of DEAF1-related disorders include seizures, malformations of the brain, behavioral disorders, autism, gastrointestinal issues, and skeletal problems including flat foot or dislocation of the hip.
- SYNGAP1-related non-syndromic intellectual disability primarily affects the central nervous system. Moderate to severe intellectual disability is usually apparent in infancy and early childhood. Some affected people may also have seizures and/or autism spectrum disorder (ASD).
- 16p11.2 Deletion Syndrome is caused by a missing “deleted” piece on chromosome 16. This syndrome usually includes developmental delay and intellectual disability, and, most often, at least some features of autism spectrum disorder. Some affected individuals have minor physical abnormalities, including an increased risk for obesity. Symptoms vary. Some affected people appear to have absolutely zero physical, intellectual, or behavioral abnormalities.
- Primrose Syndrome, was originally described in 1982. Less than a dozen cases have been reported. The most distinctive feature is a hardening of the outer ear (calcification). Other features can include certain characteristic facial features, a large head (macrocephaly), and intellectual disability. Neurological signs such as autism, brain calcifications, and behavioral abnormalities have been reported in some cases as well. Additional characteristics including diabetes, sparse body hair, and muscle wasting may appear in adulthood.
Rare disease with or without autism symptoms
If you have noticed certain characteristics in yourself or your child that may point to a rare disease or autism, or if you have been referred for testing, have been considering getting tested, or have received abnormal results on your tests, you may wish to speak with a genetic counselor. A genetic counselor is professionally trained to understand and explain your results, direct you to services that may offer the support you need, and help you make informed decisions about your health or your child’s health.
We also recommend using our Child Development Checker app to assess developmental delays and potential genetic concerns at home. The app helps analyze your child’s development and identify early red flags. Plus, the “Connect to Expert” feature offers personalized support from genetic professionals. Together, these resources empower you to support your child’s unique developmental journey proactively.
