Genetic Screening Helps Identify Risk of Having Child with CF, Australian Study Shows

Genetic screening for cystic fibrosis mutations helps individuals and couples identify their risk of having a child with the disease, an Australian study shows.

The research, published in the journal Genetics in Medicine, is titled “Reproductive genetic carrier screening for cystic fibrosis, fragile X syndrome, and spinal muscular atrophy in Australia: outcomes of 12,000 tests.”

Genetic screening for CF has been available in Victoria, Australia, since 2006. In late 2012, the Victorian Clinical Genetics Services developed a multi-disorder genetic screening tool called prepair. It not only tests for CF, but also for spinal muscular atrophy and fragile X syndrome.

Researchers checked the results of the first 12,000 screenings. They identified 610 people with mutations: 342 for CF, 241 for spinal muscular atrophy, and 35 for fragile X syndrome.

The CF screening covered 38 mutations of CFTR, the gene that’s defective in CF. Those 38 account for 90 of people with CF mutations in white Australians.

Mutations cause the gene to produce a faulty protein — and this abnormality leads to the buildup of thick, sticky mucus in lungs and the digestive system.

Victoria followed American College of Medical Genetics and Genomics in deciding to test for 23 CF mutations. In deciding to test for the other 15 mutations, it took into account their frequency in the Australian population and the severity of the disease that a mutation is associated with.

In addition, “individuals with a known familial variant [a mutation running in a family] that was not included in the 38 panel were offered testing for that variant,” the researchers wrote.

The test identified 22 CFTR mutations in the 342 carriers. Ninety-seven percent, or 331, had mutations that the American College of Medical Genetics and Genomics recommends be tested for. Three percent, or 10 carriers, had six other mutations that the customized test screened for. And one carrier had a mutation running in the family.

The screening identified 14 individuals or couples at increased risk of having a child with CF. Six had a family history of the disease.

“For 12 of the 14 CF carrier couples, both partners were carriers of a CFTR variant in the ACMG [American College of Medical Genetics and Genomics] list of 23 variants recommended for population screening,” the researchers wrote.

Testing confirmed a CF diagnosis in four cases of a wife’s pregnancy. Three of the four couples in those situations decided to terminate the pregnancy.

Overall, “offering screening through a coordinated clinical and laboratory service ensures patients are supported to make informed reproductive choices,“ the team concluded.