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Non white cystic fibrosis patients carry varied genetic mutations for condition

Most genetic testing for cystic fibrosis does not contain mutations on the screening panel for identifying the condition in non-white carriers of the disease, according to recent research.

“We think that this information can be used to optimize newborn screening programs, taking into account the ethnic composition of state populations, resulting in earlier diagnosis and intervention, timely clinical treatment, and enhanced prognosis,” Iris Schrijver, MD, professor of pathology and pediatrics at Stanford University School of Medicine and director of Stanford Molecular Genetic Pathology Service in Stanford, California, stated in a press release. “We believe it could propel equity in mutation detection for white and non-white [cystic fibrosis (CF)] patients.”

Schrijver and colleagues evaluated 22,206 non-Hispanic white, 1,955 Hispanic, 1,214 black, 156 Asian and 71 Native American patients with CF for mutations in the CFTR gene that would led to CF. Although a majority of white (90%) and Native American (83%) patients had the p.Phe508del mutation — with about half of those patients carrying two copies of the mutation — 41% of Asian, 38% of black and 30% of Hispanic patients had this mutation.

Further, there was a greater disparity in genotyping by ethnicity; between 2008 and 2013, progress in genotyping improved from 21% to 9% in white patients, while Hispanic patient genotyping improved from 29% to 15%, black patients improved from 39% to 19%, Asian patients improved from 29% to 16% and Native American patients improved from 19% to 8%.

When analyzing CTFR mutations in non-white patients, they found 89 of 140 patients had two CFTR variants, with seven new and unique variants. A multiplex ligation-dependent probe amplification showed 14 rearrangements in 51 patients, with six new and unique rearrangements.

“Our results confirm the widely held notion that the American College of Medical Genetics and Genomics list of 23 mutations that was specifically designed for carrier screening is inadequate for diagnostic testing, even though it is used widely,” Schrijver stated in the release. – by Jeff Craven

Disclosure: Schrijver reports receiving grants from the Cystic Fibrosis Foundation Therapeutics Inc.