Down Syndrome: Symptoms & Signs

Medically Reviewed on 9/10/2019

Down syndrome is a genetic disorder and a common chromosome abnormality in humans, in which an embryo contains extra genetic material from chromosome 21. These extra genes and DNA cause changes in development of the embryo and fetus leading to both physical and mental abnormalities. Not every patient with Down syndrome will have all the signs and symptoms or have symptoms and signs with the same degree of severity. Some characteristic signs and symptoms include intellectual disability, a small head, short neck, a flat face, upward slanting eyes, flat, low-set ears, and a protruding tongue.

Causes of Down syndrome

The most common cause of Down syndrome is trisomy 21, where the embryo gets three copies of chromosome 21, instead of two. Translocation describes a less common cause of Down syndrome in which an extra piece of chromosome 21 attaches to another chromosome.

Other down syndrome

  • Bowlegs
  • Developmental Delay
  • Flat Ears
  • Flat Face
  • Flexible Joints
  • Intellectual Disability
  • Lack of Muscle Tone
  • Large and Protruding Tongue
  • Low-Set Ears
  • Motor Delay
  • Obesity
  • One Single Flexion Crease on the Palm of the Hand
  • Short Neck
  • Short Stature
  • Small Head
  • Speech Delay
  • Upward Slanting Eyes
  • Wide Hands With Short Fingers

Subscribe to MedicineNet's Children's Health & Parenting Newsletter

By clicking "Submit," I agree to the MedicineNet Terms and Conditions and Privacy Policy. I also agree to receive emails from MedicineNet and I understand that I may opt out of MedicineNet subscriptions at any time.

"Down Syndrome." National Down Syndrome Society. <>.