DS Behavioral Phenotype Part I: Say what?

Stereotypes about Down syndrome are frustrating, and the one I am often most shocked by is the assumption that all people with DS are the same. I try to give people the benefit of the doubt because before I had Grace, I didn’t know anyone with DS. I believed things then that are so obviously false to me now. I thought, for example, that my difficulty in understanding how some people with DS speak was attributable to their level of intellect, not their oral muscle tone and functioning. Yes, I, too, was once uninformed. (I know. Give it a minute. Let your shock dissipate before moving on.)

Of course, not even identical twins are exactly alike and no two people with DS are the same, either. However, research shows that there are patterns of development among individuals with DS in their unique relative strengths and weaknesses as related to cognition (thinking and learning) and behavior. Decades of research have gone into forming a unique behavioral phenotype for Down syndrome that highlights patterns in important behaviors during different developmental periods.

Before we move on, let’s take a little trip down memory lane to ninth grade biology. Punnett squares, anyone? In my seven years of freshman bio (don’t worry, only one as a student), I learned that phenotypes are the observable characteristics resulting from an organism’s genes and interactions with the environment. We know that people with DS share a unique genetic mutation involving the 21st chromosome. We also know that this affects characteristics ranging from brain anatomy to muscle tone, to propensity toward vision and hearing issues. So, it makes sense that although each individual with DS is unique, many do share patterns in how they absorb, process, and respond to the people and environment around them.

That is good news because evidence-based information is reliably useful not only for helping parents but also for therapists, physicians, school districts, and teachers to know how to best support the development of people with DS in their respective areas.

What is a behavioral phenotype?

The Down syndrome behavioral phenotype is:

  • Probabilistic, meaning people with DS are more likely (but not guaranteed) to show these trends in behaviors
  • A guide for monitoring areas of probable weakness to ensure timely intervention (therapy, education) to address them
  • A way of adapting interventions (educational, therapeutic, medical) to better meet the needs of people with DS
  • A way of better understanding relative strengths and weaknesses in people with DS to improve independence and quality of life

The Down syndrome behavioral phenotype is NOT:

  • A suggestion that all people with DS are the same
  • An intention to ignore or override what is known about an individual with DS
  • A flawless look at development – most studies on this topic look at individuals at distinct ages from infancy through late adulthood, but few follow individuals throughout to the lifespan to see how these characteristics actually change as an individual develops.  

What are some of the main characteristics of the DS phenotype?

There are quite a few characteristics in the phenotype. For example, people with DS show relative strength in understanding information they see, as compared with information they hear. They also show a stronger ability to understand what is communicated to them, compared with their ability to express their own thoughts. In Part II of this post, I will describe and give examples of phenotype characteristics in four main areas: cognitive, social, speech and language, and motor skills.

Why is the phenotype important?

Supporting people with DS by addressing areas of need and providing opportunities for learning and growth that utilize strengths can help to reduce frustration and undesirable behaviors, increase learning and academic success, and promote independence.

How can we use this knowledge?

That’s a big part of what I’ll talk about here on The Extra Life. Part II of this post will give some basic information. But moving forward, much of the information I present will take into account the Down syndrome behavioral phenotype and give you strategies for meeting these needs and building on strengths at home, in therapy, and at school.

I can’t wait to read Part II!

Are you on-edge-of-your-seat excited for Part II? Be among the first to know when I post it! Subscribe to my blog in the right sidebar or at the bottom of this page. Just type in your email address and click “Follow” to receive all of my latest posts by email.  

The Emerging Down Syndrome Behavioral Phenotype in Early Childhood: Implications for Practice. By: D. Fidler

Down Syndrome: Cognitive and Behavioral Functioning Across the Lifespan. By: J. Grieco, M. Pulsifer, K. Seligsohn, B. Stotko, and A. Schwartz

The Down syndrome behavioral phenotype: Taking a developmental approach. By: D. Fidler, D. Most, and A. Philofsky

4 thoughts on “DS Behavioral Phenotype Part I: Say what?

Add yours

  1. Very helpful information to share Heather, thanks. Yes I’m can’t wait to read part ll. A lot has changed in like 24 years of education, but being a IA, I don’t always get all of the information that’s out there so this has been most enlightening to me.


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