Features

Ethnic Differences in CF Genetic Coding

Diagnosis at a later age proves difficult when dealing with hundreds of possible mutations in cystic fibrosis.

In 2014 National Geographic debuted its 125th anniversary issue. On the cover was a grid of 25 different faces including men, women and children dubbed "The Changing Faces of America" and depicting what the average American could look like in the year 2050 as racial mixing increases with each new generation. The accompanying article talks about the increase of Americans who identified as more than one race from 9 million on the 2010 U.S. Census compared to 6.8 million on the 2000 census.1

Diagnosis

Although the United States has long been known as the great melting pot of the world this ethnic diversity presents a big challenge in the medical community, specifically in diagnosing cystic fibrosis.

Using the Cystic Fibrosis (CF) Foundation Registry, Stanford University researchers looked at CFTR genotyping across different racial and ethnic groups.

The study, published in The Journal of Molecular Diagnostics, found differences in the genetic coding of whites and nonwhites who are often diagnosed at a later age. Researchers believe one reason for this ethnic disparity in the diagnoses of cystic fibrosis is that the variants examined in the most common cystic fibrosis newborn screening panels do not include all of the possible mutations present in nonwhite populations.2

"If you order the very basic cystic fibrosis mutation screen it only covers the most common mutations," explained Whitney Brown, MD, director of the Cystic Fibrosis Program at Inova Advanced Lung Disease and Transplant Program based in Falls Church, Va.

SEE ALSO: Cystic Fibrosis Screening for Newborns

Two years ago Brown diagnosed a 21-year-old African American man with cystic fibrosis after supplementing a basic cystic fibrosis screen with a sweat chloride test.

"When I ordered this test for him only one of his mutations was in that common 32, so if I hadn't done the sweat chloride test and didn't have all of the history that would suggest he was a carrier and didn't have the disease."

The young man had been told by other providers that he had asthma but cystic fibrosis, an inherited disorder that damages the lungs and digestive system can be far more life-threatening.

And he is not alone with the researchers at Stanford finding 30% of Hispanics, 38% of blacks, and 41% of Asians in the registry did not even have one copy of a cystic fibrosis mutation that was common in more than 80% of white and Native Americans.  In total there are more than 1,800 known mutations of the cystic fibrosis gene according to Cystic Fibrosis Foundation.3

Cystic fibrosis screenings are now universal across the US. Each state's health department makes a point of disclaiming on their websites the fact that there is still a chance a baby has cystic fibrosis even if their basic screen comes back negative. As a result follow-up testing may be ordered.

"We should not exclude the diagnosis of cystic fibrosis without sequencing the gene for anyone we're suspicious of," stressed Brown. "We shouldn't stop at the 32 or the 100th and say 'well we can't find a mutation so they probably don't have CF' and look harder."

An early diagnosis is important as with any illness or disease because it allows treatment to begin sooner before people start showing symptoms. Studies find that children with cystic fibrosis who receive immediate care have improved growth and lung function, reduced hospital stays and a better life expectancy overall.4

Treatment

Some treatments similarly depend on identifying the exact mutation, meaning challenges can remain even after a cystic fibrosis diagnosis has been confirmed. As the world of healthcare moves toward personalized medicine, pharmacogenetic therapies are being developed to target specific genetic mutations.

Kalydeco for example made by Vertex Pharmaceuticals of Cambridge, Mass., targets the G551D mutation in patients 6 and older.5 While researchers saw positive results in the 2012 clinical trials, the drug is expected to help only a small fraction of cystic fibrosis patients; specifically 4% of people living with cystic fibrosis who have the G551D mutation.

More recently the FDA approved Orkambi to treat patients age 12 and older with cystic fibrosis who have the F508del mutation which is a leading cause of the disease. This mutation causes the production of an abnormal protein that disrupts how water and chloride are transported in the body.6

One way to help pinpoint their patient's mutation and see if targeted therapies are an option is to undergo genetic testing. The Cystic Fibrosis Foundation's Mutation Analysis program for example offers it for free through Johns Hopkins Hospital in Baltimore to eligible patients.

On a final note providers will be able to best help their patients by keeping cystic fibrosis as a potential diagnosis and not ruling it out on the first try. It can no longer be thought of as "a white man's disease" as the white and nonwhite populations in the US will only continue to "gray."

Chelsea Lacey-Mabe is a staff writer. Contact: clacey-mabe@advanceweb.com

1. U.S. Census Bureau. The Two or More Races Population: 2010-2012 http://1.usa.gov/1PzSera
2. The Journal of Molecular Diagnostics. The Spectrum of CFTR Variants in Nonwhite Cystic Fibrosis Patients 2016 http://bit.ly/209c5Pw
3. Cystic Fibrosis Foundation. Know Your CF Mutations http://bit.ly/1P87Zq8
4. Cystic Fibrosis Foundation. Newborn Screening for CF http://bit.ly/1S0ScL8
5. International Weekly Journal of Science. Drug bests cystic fibrosis mutation 2012 http://bit.ly/1PAGaWH
6. U.S. Food and Drug Administration. FDA approves new treatment for cystic fibrosis 2015 http://1.usa.gov/1NzK3Im

You Might Also Like...

Respiratory Therapist Workforce Report

Projected outlook is a breath of fresh air for people considering this line of work.

Early Pneumonia and Adult Asthma

First objective 35-year pulmonary study confirms lower lung function into adulthood.

Promising Treatments for Cystic Fibrosis

Scientific breakthroughs could improve quality of life for patients with CF.

New Tool for COPD

Psychological approach may help physiological reactions.


Articles Archives


     

Email: *

Email, first name, comment and security code are required fields; all other fields are optional. With the exception of email, any information you provide will be displayed with your comment.

First * Last
Name:
Title Field Facility
Work:
City State
Location:

Comments: *
To prevent comment spam, please type the code you see below into the code field before submitting your comment. If you cannot read the numbers in the below image, reload the page to generate a new one.

Captcha
Enter the security code below: *

Fields marked with an * are required.

View the Latest from ADVANCE

 

Search Jobs

Go
 
 
 
 

Back to Top

© 2017 Merion Matters

660 American Avenue Suite 300, King of Prussia PA 19406

1-484-804-4888