A new study suggests that all babies with a known mutation for cystic fibrosis (CF) and second mutation called the 5T allele should receive additional screening in order to better predict the risk of cystic fibrosis later in life. According to a Science Daily news report, the results of the study show that adding specific DNA sequencing to current newborn screenings may increase the number of CF diagnoses in the United States and would allow for early diagnosis in ethnically diverse populations. Such diagnoses could result in earlier treatment and ultimately improve the outcome and prolong the child’s life.

The researchers evaluated the effect of the 5T allele, a specific CFTR gene variant that is carried by nearly one in 10 people. They followed the cohort of babies detected through CF newborn screening with a variant detected in both of their CFTR gene copies (one 5T allele and one severe CF-causing mutation). This cohort was followed over 8 years in order to describe clinical outcomes. The research team was able to generate risk predictions based on the “TG repeat,” a DNA repeating pattern of varying length found directly adjacent to 5T alleles.

The Science Daily news report indicates that newborns with the 11 TG, a measurement of the length of the repeat, showed no signs of CF during the 8-year follow-up, although 6% of babies with the 12 TG developed the disease and close to 40% of children with the 13 TG were considered to have CF within 8 years of birth. Senior author of the study Richard B. Parad, MD, MPH, says, “The study’s conclusions show that, depending on the 5T-TG repeat length information, the risk of presenting a natural history consistent with CF can be anticipated. Right now, these babies are not detected by CF newborn screening in states other than California.”

Parad adds that instead of being detected in an asymptomatic state and followed closely, these babies later present with symptoms of CF and an important opportunity to initiate early, appropriate therapies during a window that might have improved their long-term outcome may have been missed.

Lead investigator Danieli Salinas, MD, says, “Having CFTR-DNA sequencing as part of a newborn screening model can unveil the full spectrum of this disorder, through early detection of mild to severe cases in an ethnically diverse population. Studies like this are important to better guide providers and families, by determining which individuals with which mutation combinations should be clinically monitored.”

Source: Science Daily