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If you’re considering in vitro fertilization (IVF) and preimplantation genetic testing (PGT), you may wonder about potential risks to your future child. A common question is: Is intellectual disability genetic? Understanding the causes of intellectual disability can help prospective parents make informed decisions. In this post, we explain what intellectual disability is, explore its genetic causes, and discuss how whole genome PGT can provide insight for families planning a healthy future.

What is Intellectual Disability?

Intellectual disability (ID) is a developmental condition characterized by significant limitations in cognitive ability, learning and everyday adaptive skills. Individuals with ID typically have an IQ around 70 or below and may struggle with specific types of learning, problem-solving, and independent living. This condition often arises before adulthood (usually identified in childhood) and can range from mild to profound. Children with intellectual disability often experience developmental delays in milestones like speech, learning, or self-care, and they may require extra support in school and daily life.

Genetic Causes of Intellectual Disability

Intellectual disability can have many causes, and genetics plays a major role in a substantial number of cases. Research suggests that roughly one-third of intellectual disability cases have an identifiable genetic cause (according to Orchid’s educational guide on ID and genetics). Some of the known genetic contributors include:

• Chromosomal abnormalities: An extra or missing piece of a chromosome can affect development. For example, Down syndrome (caused by an extra copy of chromosome 21) is a genetic condition that leads to intellectual disability.
  
• Single-gene disorders: A change in a specific gene can cause intellectual disability. Fragile X syndrome, for instance, is due to a mutation on the X chromosome and is one of the most common inherited causes of intellectual disability.
  
• New (de novo) mutations: Sometimes a genetic change arises spontaneously in an embryo (with no family history). For example, a new mutation in a crucial developmental gene can result in conditions like Rett syndrome, leading to intellectual disability even when parents have no known genetic issues.
  

It’s important to note that not all intellectual disabilities are genetic. Some cases result from non-genetic factors such as pregnancy complications, birth injuries, or environmental exposures. Often the causes are  multifactorial, implicating  a mix of genetic and environmental influences. However, understanding the genetic component is key, since it accounts for a significant portion of ID cases and is something we can screen for before pregnancy.

How Whole Genome PGT Can Help

Whole genome preimplantation genetic testing (PGT) is an advanced option during IVF that can shed light on an embryo’s genetic health before pregnancy begins. This testing involves sequencing the embryo’s entire DNA to look for genetic abnormalities. Whole-genome PGT, like Orchid’s embryo screening, can detect a wide range of genetic factors linked to intellectual disability in a single comprehensive test. This includes checking for chromosomal issues (such as extra or missing pieces that could cause conditions like Down syndrome) as well as hundreds of single-gene mutations associated with neurodevelopmental disorders. In fact, Orchid’s embryo screen analyzes 200+ known genetic variants that are tied to intellectual disability, developmental delays, autism, and related conditions (drawing on decades of genetic research in these areas).

What does this mean for prospective parents? By screening embryos at the genetic level, PGT provides actionable insight before the  pregnancy begins. For example, if an embryo is found to carry a mutation known to cause a severe intellectual disability syndrome, parents and doctors can choose not to transfer that embryo and instead select one with a healthier genetic profile. Likewise, if all tested embryos lack high-risk genetic markers, families gain reassurance that the risk of certain genetic causes of intellectual disability is greatly reduced. Importantly, whole genome PGT can identify both inherited risk factors and many spontaneous (de novo) mutations – the kind that would not be evident from standard carrier testing or family history alone. This proactive approach empowers families to avoid or prepare for genetic conditions before a child is conceived.

It’s also crucial to have realistic expectations. No genetic test can detect every possible cause of intellectual disability. PGT focuses on known genetic variants, so a “clear” result means the embryo has no known high-risk mutations for the conditions screened – it does not guarantee zero chance of any developmental issues. Some intellectual disabilities stem from factors that genetic tests cannot screen for. Nonetheless, using whole genome PGT significantly improves the ability to identify major genetic risks ahead of time, providing  a much better understanding of an embryo’s health than IVF alone.

Final Thoughts

So, is intellectual disability genetic? In many cases it can be, with numerous intellectual disabilities traced to genetic causes – ranging from chromosome differences to single-gene mutations. For hopeful parents going through IVF, modern tools like whole genome PGT offer a valuable window into these genetic factors before pregnancy, helping prospective parents stack the odds in favor of a healthy baby. While PGT isn’t a crystal ball for all outcomes, it does arm couples with knowledge about known genetic risks for intellectual disability and other disorders, enabling more informed choices in  family planning.

As options are considered, remember that guidance is available. Speaking with a genetic counselor or fertility specialist can help address a family’s specific risk factors and the benefits and limits of genetic screening. Additionally, resources like Orchid’s Guides provide educational information on how genetics can impact a child’s health. Through education, couples are provided with the opportunity to take advantage of advanced genetic testing when appropriate. The IVF journey is then approached with greater confidence and peace of mind in building a healthy family.