Caused by three copies of chromosome 21 - also called trisomy 21

Clinical features

• Hypotonia
• Brachycephaly (small head with a flat back)
• Short neck
• Short stature
• Distinctive facial features
  • Prominent tongue
  • Flattened face and nose
  • Prominent epicanthic folds
  • Brushfield spots

Complications

• Develop at a different pace
• Learning disability common
• Recurrent otitis media
• Deafness - eustachian tube abnormalities lead to glue ear and conductive hearing loss
• Visual problems such myopia, strabismus and cataracts
• Hypothyroidism occurs in 10-20%
• Cardiac defects affect 1 in 3, particularly ASD, VSD, patent ductus arteriosus and tetralogy of Fallot
• GI issues - Hirschsprung’s disease, duodenal atresia
• Atlantoaxial instability
• Predisposed to developing diabetes and coelic
• Leukaemia is more common in children with Down’s
• Dementia is more common in adults with Down’s