Mental impairment  limits intellectual abilities and adaptive behaviors (conceptual, social, and practical skills people use to function in everyday lives).  Most people with Down syndrome have IQs that fall in the mild to moderate range of  people with Mental impairment.  They may have delayed language development and slow motor development.  

Physical signs of Down syndrome include:

  Flat face with an upward slant to the eye,
  Short neck, and abnormally shaped ears
  Deep crease in the palm of the hand
  White spots on the iris of the eye
  Poor muscle tone, loose ligaments
  Small hands and feet  

Other health conditions in Down syndrome:

  Congenital heart disease
  Hearing problems
  Intestinal problems like blocked small bowel or esophagus
  Celiac disease  
  Eye problems like cataracts
  Thyroid dysfunctions
  Skeletal problems
  Dementia—similar to Alzheimer’s