Newborns with respiratory distress should be evaluated for primary ciliary dyskinesia
Feb 21, 2007 - 6:05:24 AM
Newborns with respiratory distress should be evaluated for primary ciliary dyskinesia, a rare genetic disease that has features similar to cystic fibrosis, says Thomas Ferkol, M.D., from Washington University School of Medicine in St. Louis. He reports finding that about 80 percent of patients with primary ciliary dyskinesia (PCD) have a history of newborn respiratory distress.
"The diagnosis of PCD requires a high index of suspicion, but PCD must be considered in any term newborn who develops respiratory distress or persistent hypoxemia (low oxygen in the blood), especially those who have reversed internal organs or an affected sibling," says Ferkol, director of the Division of Pediatric Allergy and Pulmonary Medicine at Washington University School of Medicine and St. Louis Children's Hospital.
Reviewing published reports, Ferkol and Margaret Leigh, M.D., professor of pediatrics at the University of North Carolina at Chapel Hill (UNC), found that neonatal respiratory distress was a common clinical symptom of PCD, a chronic airway disease that affects about 1 in 15,000 children. Their findings appeared in the December issue of Seminars in Perinatology.
Also known as immotile cilia syndrome, ciliary aplasia or Kartagener Syndrome, PCD causes persistent wheezing and cough in children and is associated with recurrent or persistent sinus and ear infections. Half of patients with PCD have reversed internal organs, called situs inversus, and males are usually infertile.
In PCD patients, the cilia, tiny hairs that move mucus, bacteria and particulates out of the respiratory tract, including the lungs, middle ear and paranasal sinuses, have abnormal or no motion. As a result, the airways become obstructed and infected, which incites a destructive inflammatory process in those organs. Cilia are also present in the female reproductive system, central nervous system and gut.
"The tricky thing about this disease is that many of the clinical symptoms are very similar to other more common conditions, such as asthma, allergy or cystic fibrosis," Ferkol says. "Physicians often fail to consider PCD, in part because we don't have a great diagnostic test for the disease."
Ferkol indicates that several clinical features of PCD mirror those found in the more-common cystic fibrosis, including chronic sinus and lung disease as well as male infertility. However, chronic ear disease and neonatal respiratory distress are relatively uncommon in cystic fibrosis and should prompt the caregiver to consider PCD.
"Once children with PCD are past the newborn period, the signs and symptoms that typically bring them to medical attention are chronic ear disease, hearing loss and a runny nose that persists despite seasonal changes or the use of antibiotics and antihistamines," Ferkol says. "But as patients age, the lung manifestations become more evident. Also, infertility becomes a greater issue in adulthood."
Because definitive testing is not always readily available, patients with PCD are often diagnosed late. In addition, treatment of PCD in the community is highly variable, largely because the necessary clinical studies have not been performed.
Ferkol, also associate professor of pediatrics and of cell biology and physiology and director of the Cystic Fibrosis Center at Washington University School of Medicine, is leading the Washington University research team that is part of a national consortium investigating the genetic causes of PCD. The Genetic Diseases of Mucociliary Clearance Consortium, based at UNC, is part of the National Institutes of Health Rare Diseases Clinical Research Network.
The consortium aims to improve diagnosis and treatment of PCD as well as to better define its origin and how it progresses.
"We want to identify as many PCD patients as we can to help us understand the genetics, pathophysiology and clinical spectrum of this disease so we can devise better, more effective treatment strategies," Ferkol says.
Ultimately, members of the consortium will invite patients with PCD to enroll in a long-term study where they will be monitored and be eligible to participate in clinical trials of potential treatments, Ferkol says.
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