April 1, 2021

Rare Diseases and Autism Spectrum Disorder: What You Should Know

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Autism is a behavioral diagnosis, so it’s possible for individuals with rare single-gene disorders to receive an autism diagnosis on top of their rare disease diagnosis.

The month of April is Autism Acceptance Month (formerly Autism Awareness Month) and April 2 is World Autism Awareness Day. The purpose of these events is to build a better understanding of the signs, symptoms and realities of autism. Although autism spectrum disorder is not considered rare, there are many points of connection between people in the autism community and rare disease community.

What is autism?

Autism, or autism spectrum disorder (ASD), is a developmental disability that affects communication and behavior. Autism is known as a “spectrum” because it can look different in different people.

What causes autism?

Numerous studies show that genetics plays a role in autism spectrum disorder. ASD is a multifactorial condition, meaning both genetic and environmental factors contribute to a person’s risk of having the disorder. Usually the genetic component of that risk comes from the combined impact of many common genetic variants that individually impact risk only slightly. Much less commonly, a single rare genetic variant can cause a significantly increased risk for ASD.

What is the connection between autism and rare disease?

There is no one “autism gene” that is consistently mutated in every person with ASD. Yet, there are certain rare, single-gene disorders, or disorders caused by a variant in one out of 25,000 protein-coding genes in a human body, associated with a significantly increased risk of ASD.These rare conditions may be the cause of up to 25% of ASD cases, and can be caused by either inherited or de novo (spontaneous) genetic variants.

Autistic-like behavior is often just one of the symptoms caused by these rare disorders; many affected individuals experience a variety of symptoms that impact many different parts of the body. For example, take the rare condition fragile X syndrome. Fragile X syndrome is caused by a variant on the FMR1 gene and is the leading genetic cause of autism. One in three people with fragile X syndrome also have a behavioral diagnosis of autism. Additionally, affected individuals may experience intellectual disability, seizures, connective tissue problems, heart problems, and other symptoms.

Since autism is a behavioral diagnosis, individuals with rare single-gene disorders associated with an increased risk of autism may or may not receive an autism diagnosis on top of their rare disease diagnosis.

Sometimes, doctors do not separate the diagnoses and refer to autistic-like behaviors or intellectual disability as symptoms of an individual’s primary rare disease diagnosis.

Healthcare professionals should be aware that a diagnosis of ASD can be an indicator of an underlying rare genetic condition that may have a treatment, clinical trial, or additional research opportunities.

How is AllStripes trying to help?

At AllStripes, we have research programs for numerous rare conditions that are linked to autism spectrum disorder and intellectual disability, such as SLC6A1. We are working to better understand these conditions, and patients and caregivers can join in that effort by contributing their medical records to advance research.

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