May 12, 2010
Paging Dr. House…A Jewish infant is severely ill
Dr. House of TV fame was not available, so I was called into consultation for this 24 day old female Jewish infant. She had been hospitalized and seen by other physicians previously. Shortly after birth, when the baby was fed, she gagged and became agitated. Because of the suspicion of sepsis at this young age, intravenous antibiotics were initiated. After 48 hours, however, the cultures were negative and the antibiotics were discontinued. Feeding was re-attempted, but the baby began vomiting and gagging again on the sixth day of life. She was re-admitted to the hospital, where abdominal x-rays were reported normal with no sign of obstruction or infection and a scan of the brain was also normal. Gastrointestinal (GI) and cardiology consults were requested. The GI specialist diagnosed reflux and the cardiologist, after performing an echocardiogram and an EKG, reported that there were no heart abnormalities. The doctors diagnosed her as “failure to thrive”.
When I interviewed the mother, I learned that the baby sustained second degree burns on her back and legs first noticed during her previous hospital admission. The doctors felt that a heating blanket probably malfunctioned and overheated and caused the burn. On my examination, the baby’s lower left back showed a scar which was slightly red and well healed, consistent with the history of the second-degree burn. A neurological exam revealed generalized hypotonia (decreased muscle tone) and also an absence of the deep tendon reflexes, which is the response elicited when your doctor hits your knee with a reflex hammer. Additionally, her tongue was unusually smooth.
There are about a dozen disorders that could lead to absent or decreased reflexes in childhood. One of them which affect persons of Ashkenazi Jewish descent and which presents in infancy is known as familial dysautonomia (Riley-Day Syndrome). The incidence of this autosomal recessive disorder is about 1 in 3,600 live births and approximately 1 in 30 persons is a carrier. The defective gene has been mapped to the 9q31-33 locus.
Patients with this disorder have abnormal or reduced numbers of nerve fibers that usually carry pain, temperature and taste sensations. They also have a smooth tongue. Infants with familial dysautonomia present with poor sucking and swallowing, occasional vomiting and aspiration pneumonia. Breath-holding spells are common, followed by fainting and cyanosis, and various neurological defects. Walking is delayed and clumsy, probably because of poor sensory feedback from muscle spindles. Of significance is that when these children cry, tears are absent. Seizures are also common.
There are many specific tests to help make the diagnosis, including Amniocentesis. Genetic counseling is readily available for patients and their families.
Currently, treatment is symptomatic with certain medications that control temperature and blood pressure as well as seizures
Because of better therapy, over 40% of surviving patients are over 20 years of age. It still remains, however, a progressive and life-threatening disorder. Genetic treatment is not yet available but there are many clinical trials currently underway to correct the underlying abnormality.
In the meantime, however, Dr. Lorenz Studer from Sloan-Kettering in New York recently extracted reprogrammed or induced pluripotential cells (able to become any cell type in the adult body) from patients with familial dysautonomia and grew them in the laboratory in Petri dishes, which recapitulated the abnormalities seen in the patients. Now the doctor can experiment with medications and other therapies in an attempt to cure the disease without harming the patient.
My patient most likely developed second-degree burns on the heating blanket because she did not feel pain when the burn began and did not cry to alert the nurses or her mother that something was wrong. Her poor feeding, sucking and swallowing, along with her bouts of vomiting, were not signs of infection but rather a familial dysautonomia. The absent reflexes and the smooth tongue, along with her Ashkenazi Jewish background, were practically diagnostic for this syndrome.
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