Definition:
Riley-Day syndrome is an inherited disorder that affects nerve function throughout the body. Symptoms are present at birth and grow worse over time.
Alternative Names:
Familial dysautonomia; Hereditary sensory and autonomic neuropathy - type IIICauses, incidence, and risk factors:
Riley-Day syndrome is inherited as an autosomal recessive trait, which means that a person must inherit a copy of the malfunctioning gene from each parent in order to develop the condition.
It is seen most often in people of Eastern European Jewish ancestry (Ashkenazi Jews), where the incidence is 1 in 3,700. The disease is caused by mutation of the IKBKAP gene on chromosome 9. It is rare in the general population.
Symptoms:
- Poor growth
- Feeding difficulties
- Breath holding
- Sweating while eating
- Long episodes of vomiting
- Lack of response to painful stimuli
- Seizures
- Hypotonia, low muscle tone
- Repeated fevers
- Repeated episodes of high blood pressure
- Poor coordination - unsteady gait
- Unusually smooth tongue surface
- Decreased taste
- Diarrhea
- Constipation
- Severe scoliosis
- Skin blotching
Infants with this condition have feeding problems and develop pneumonia caused by breathing food into their airways. Vomiting and sweating spells begin as the infant gets older. Young children may also have breath-holding spells that cause them to lose consciousness, since they can hold their breath for long enough to pass out without feeling the discomfort that normal children would.
An important sign of Riley-Day syndrome is inability to feel pain. This leads to injuries that might not have occurred had the child felt the pain. Children do not feel the normal sensations such as drying of the eyes, pressure over pressure points, and chronic rubbing and chaffing. Bone and skin pain, including burns, are also poorly perceived. However, they can feel internal pain, such as menstrual cramps.
Intelligence is expected to be in the normal range.
Signs and tests:
The health care provider will perform a physical exam. The patient may have:
- Absent or decreased deep tendon reflexes
- Lack of a response after receiving a histamine injection (normally redness and swelling would occur)
- Lack of tears with emotional crying
- Tiny pupils after receiving certain eye drops
- Parents of Ashkenazi Jewish ancestry
Blood tests are available to check for IKBKAP gene on chromosome 9. The detection rate in the Ashkenazi Jewish population is greater than 99%.
Treatment:
Treatment may include:
- Protecting the person from injury
- Treatment of aspiration pneumonia
- Anticonvulsant therapy if seizures are present
- Medicines, including liquid tears, to prevent dry eyes
- Medicines called anti-emetics, to control vomiting
Postural hypotension (low blood pressure when standing) can be managed with increased fluid and salt intake, caffeine, and waist-high elastic stockings
Expectations (prognosis):
With advances in diagnosis and treatment, survival continues to improve. Currently, a newborn with Riley-Day has a 50% chance of reaching age 30.
Complications:
The following symptoms of "autonomic crises" occur in about 40% of patients:
- Excessive sweating of the head and torso
- Blotching of the face and torso
- Mottling of the hands and feet
- Hypertension (high blood pressure) and tachycardia (rapid heart rate)
- Nausea/vomiting
- Severe dysphagia/drooling
- Irritability
- Insomnia
- Worsening of muscle tone
Prevention:
Individuals of Eastern European Jewish background and families with a history of Riley-Day syndrome who are thinking of having children can seek genetic counseling to discuss risk and undergo testing where appropriate.
Genetic testing is very accurate for Riley-Day syndrome and may be used for diagnosis of affected individuals as well as for carrier detection and prenatal diagnosis.
