There are many characteristic signs and symptoms associated with Down syndrome. Not every child will haveall of these and the degree to which they are affected may vary greatly. Signs and symptoms include:

• A small head with small, low-set ears
• Slanting eyes, a broad flat face, and a short nose
• A small mouth and protruding tongue
• Short, small but broad hands and feet and a single crease across the palm
• Short fingers and an abnormal bone in the 5th finger
• Poor muscle tone (hypotonia)
• Hyperflexible joints
• Atlantoaxial instability (a malformation of the top of the spine)
• Mild to moderate mental retardation

Complications of Down syndrome vary greatly. Some may be present at birth, some may arise during childhood, others during adulthood, and others may never be experienced. Doctors and family members must be aware of these potential complications as patients may or may not be able to clearly communicate their symptoms and/or may express them in unexpected ways.

Complications can include:

• Coeliac disease
• Dental disease
• Developmental delays
• Diabetes
• Food sensitivities and constipation
• Gastrointestinal abnormalities and obstructions (5 to 10%)
• Hearing loss (75%)
• Heart defects and disease (close to 50%)
• Increased incidence of respiratory and ear infections, colds, bronchitis, tonsillitis, and pneumonia
• Increased risk of acute leukaemia
• Premature aging, loss of cognitive abilities, and Alzheimer’s type symptoms in patients under 40 years of age
• Seizure disorders
• Sleep apnoea (50 to 75%)
• Spinal cord compression
• Thyroid disease (about 15%)
• Visual problems, including cataracts (about 60%)