Symptoms of FD include:
- hypotonia (poor muscle tone)
- feeding difficulties
- poor growth
- lack of tears
- attacks of nausea with vomiting
- frequent lung infections
- difficulty maintaining body temperature
- erratic swings in blood pressure.
Older infants and young children with FD may hold their breath for long periods of time, which may cause cyanosis (a bluish appearance of the skin or lips) or fainting. Developmental milestones, such as walking and speech, are usually delayed, although some affected individuals show no signs of developmental delay. Other problems include:
- scoliosis (curvature of the spine)
- poor bone quality and increased risk of bone fractures
- kidney and heart problems.
About one-third of children with FD have learning disability. By adulthood, affected individuals often have increasing difficulties with balance and walking unaided.
Other problems that may appear in adolescence or early adulthood include lung damage due to repeated infections, impaired kidney function, and worsening vision due to the shrinking size (atrophy) of optic nerves, which carry information from the eyes to the brain.
'Dysautonomia crisis' is a group of symptoms that include nausea, high blood pressure, fast heart rate and a change in personality. It is usually caused by stress. Episodes can occur as frequently as daily, but some patients will never experience a crisis.