Familial dysautonomia

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

Causes

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

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.

Exams 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

Outlook (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.

Possible 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

When to Contact a Medical Professional

Call your doctor if symptoms change or worsen.

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.