Symptoms include:
Wide-set eyes
Microcephaly: technical term for a small head
Low-set ears
Epicanthic folds: extra folds of skin on the eyelid
Palmar creases (also called a simian crease)

High pitched ‘cat cry’ primarily during infancy
Hypotonia during infancy
Hypertonia in later years
Difficulty swallowing
Intellectual disability
Language development problems
Short attention span
Hyperactivity and other behavior problems

Symptoms that are likely to accompany but are not symptoms for a diagnosis are heart defects, cleft palate and lip, skeletal problems generally in the lower body, and digestive problems.

These symptoms may not be harmful or even much of a hassle themselves but can lead to other problems that do cause suffering.