Why is Down syndrome a syndrome?

Syndrome from The Incredibles

October is National Down Syndrome Awareness Month. In previous posts, I’ve discussed what is Down syndrome and why the condition is called “Down syndrome.” But why is it a “syndrome?”

Medically-speaking, a “syndrome” describes a group of symptoms that occur together and characterize a particular condition. This is what Dr. Down did when he wrote the first paper describing Down syndrome. He described a group of symptoms that occurred with certain of his patients with intellectual disability that seemed to characterize their particular condition. To this day, this is how most visual diagnoses are made of Down syndrome.

In a postnatal setting, the labor and delivery team may suspect a child has Down syndrome because the child has low muscle tone where her arms and legs lay out from the body. The medical team may notice the shape of the child’s eyes, a single crease across the child’s palm, or a thong-gap between the big and second toe.

Prenatally, an obstetrician may notice a thickening of the back of the fetus’s neck, the long bones being shorter than average (i.e. the humerus in the upper arm and femur in the leg), a shorter than average pinky finger, or the absence of a nasal bone on ultrasound. All of these are considered “soft” markers that may suggest the fetus has Down syndrome. The obstetrician may also notice a malformation of the heart or gastrointestinal track as other characteristics that are not definitive for Down syndrome but associated with a certain percentage of children born with the condition.

All of these, and others, are characteristics to describe the syndrome named after Dr. Down. Syndromes, however, are named that because the underlying cause for the condition is unknown. AIDS, Acquired Immune Deficiency Syndrome, was termed that because its cause was not known until the Human Immunodeficiency Virus (HIV) was discovered. SARS, Severe Acute Respiratory Syndrome, was so named because patients were exhibiting a group of symptoms before the discovery of the underlying cause, the coronavirus. Even Shaken-Baby Syndrome describes characteristics associated with children who have been shaken, but does not determine that the child’s injuries were in fact caused by being shaken.

In the case of Down syndrome, though, the use of the word “syndrome” is outdated and regrettable.

It’s outdated because the cause of the condition described by the characteristics of the syndrome has been known since the 1950’s. Down syndrome is not caused by the individuals having intellectual disability, a penchant for mimicry, or a single crease across the palm. It’s caused by an extra copy of the 21st Chromosome, most commonly Trisomy 21.

The continued use of the word “syndrome,” therefore, is regrettable. It’s difficult to think of a condition described as a “syndrome” that people would want to have. Almost universally, something described as a “syndrome” is something to be avoided and even feared. In pop-culture, the China Syndrome, was a movie about a nuclear reactor meltdown. Stockholm syndrome describes a hostage becoming sympathetic to the views of her captors. And, for many children today, “Syndrome” is the villain in the Pixar movie, The Incredibles (pictured above).

The name “Down syndrome” unfortunately compounds its negative connotations. “Down,” though named for a 19th Century English physician, has a negative association, suggesting that a person’s IQ, capabilities, and worth are “down” or lower than others. Popularly, “syndrome,” is a word most often associated with deadly diseases of unknown origin, and is so negative that it was chosen as the name of a movie super-villain to scare children.

So why is Down syndrome still a “syndrome” when its cause has been known for over 50 years? Essentially, because we keep calling it that.

UPDATE: This post is discussed at episode two of the Down Syndrome Prenatal Testing Podcast, available at this link.