Rare genetic mutation could explain chronic lung disease in Indigenous children, MUHC study

Scientists at the Research Institute of the McGill University Health Centre say a rare genetic mutation has been found to cause a chronic lung disease. THE CANADIAN PRESS/Graham Hughes

A team of Montreal scientists has found that a chronic lung disease in Indigenous children is caused by a rare genetic mutation and that respiratory symptoms shouldn't be routinely blamed on factors like the child's socioeconomic conditions or past infections.

The study was recently published in The Journal of Pediatrics.

The disease in question is called primary ciliary dyskinesia (PCD). Symptoms include a chronic wet cough and nasal congestion, recurring pneumonia and ear infections.

They're serious health concerns that often result in hospitalization, a press release issued on Monday by the Research Institute of the McGill University Health Centre (RI-MUHC) explained.

That's in part because PCD often goes unnoticed and untreated.

"There's certainly some bias there. And for many reasons that are not nice reasons," said lead investigator Dr. Adam Shapiro in an interview with CTV News, referring to biases that are inherent in health care received by Indigenous populations.

"But also, this disease is difficult to diagnose. There are many different genes, over 50 genes that cause it and new ones are discovered all the time," added Shapiro, who is also a pediatric respirologist at the Montreal Children's Hospital.

As a result, young patients' lung disease is often viewed as a consequence of a severe infection in infancy instead of being diagnosed as PCD.

Now that the MUHC-RI researchers have helped determine that PCD may be more common in the First Nations than previously thought, the authors have a key takeaway for doctors: when they see Indigenous children with respiratory symptoms and who have permanent airway damage, they should suspect PCD as a cause.

"They should think of it, they should ask about it and they should do genetic testing. They should never assume a child has a chronic airway disease because of a previous infection or because of exposures in their environment," said Shapiro who has one of the largest PCD clinics in North America.

EARLY DIAGNOSIS, BETTER OUTCOMES

Sometimes the reasons given to explain the child's respiratory symptoms include "overcrowded housing, high rates of tobacco exposure, poor vaccination uptake and damage after severe respiratory infection in infancy," the RI-MUHC release said.

Now there are better answers. Scientists here, working with colleagues in Canada and the United States, followed a genetic trail. They discovered four cases of PCD among unrelated Indigenous North American children caused by mutations in a rare gene.

That indicates, Shapiro said, that further genetic testing and population studies could detect more PCD patients.

"It's (among) many different tribes, Native American and First Nations groups from the Atikamekw to the Algonquin here in Quebec, to the Ojibwe in Minnesota all the way to the Red Earth (Cree) Nation in Saskatchewan," Shapiro said.

Once physicians recognize the symptoms and confirm PCD early in life by ruling out other illnesses and testing for the disease, they can put preventive therapies in place.

Children with PCD have a hard time getting infected mucus out of their lungs, so clearing their airways can be helpful as well as treating them aggressively with antibiotics.

"Also many of these children have such severe disease they can be deaf and so getting them to an otolaryngologist, getting them ear tubes…and getting speech therapy can really improve their quality of life," Shapiro said.