Confirmatory genetic testing may be useful in the diagnosis of hemoglobinopathies for newborns with an abnormal hemoglobin (Hb) pattern, according to a recent study.
The findings suggest further research is needed to evaluate whether genetic testing programs for newborns could have diagnostic value in the clinical setting.
“We studied a consecutive cohort of newborns with an ‘FSA’ pattern (a suspected diagnosis of HbSbeta+) on the initial newborn screening test,” explained Lisa M. Shook of the University of Cincinnati and colleagues. The results were published in the International Journal of Neonatal Screening.
The retrospective study included a total of 1,151 newborns with an abnormal Hb pattern, 31 of which had an FSA pattern. The newborns were screened for hemoglobinopathies from 2015 to 2018. The findings of the initial newborn screening test (a suspected diagnosis of HbSbeta+) were compared with the diagnosis established using both protein-based and genetic confirmatory testing. Protein-based testing cannot accurately detect several hemoglobinopathies in newborns, especially when beta-thalassemia mutations are involved, according to the authors.
“During this study period, genetic testing was not universally applied in advance; it was used based on clinical suspicion,” the researchers wrote.
Among newborns with an FSA pattern, the mean gestational age was 38.7 weeks. In total, 17 newborns received genetic testing, and 30 had protein-based confirmatory testing.
“In this consecutive cohort of 31 newborns with a suspected diagnosis of HbSbeta+ based on initial newborn screening (an FSA pattern), none actually had HbSbeta+. All had the sickle cell trait (HbAS), instead; that is, we found that an initial FSA pattern was much more likely to indicate a final diagnosis of HbAS than HbSbeta+,” the authors wrote.
This meant that two-thirds of these newborns had a correct diagnosis of HbAS established at 2-4 weeks of age by protein-based confirmatory testing (and confirmed by genetic testing in a subset), but that the remaining one-third still had an incorrect, suspected diagnosis of HbSbeta+. This could lead to unnecessary treatment and testing of infants and incorrect, disease-focused counseling of parents and family members, according to the authors.
Two key limitations of the study were the small sample size and retrospective design.
“Based on this experience in which genetic testing was not universally applied, we now perform simultaneous protein-based and genetic testing as our standard clinical practice,” they concluded.
The study was funded by the National Institutes of Health and the Ohio Department of Health. The authors reported having no conflicts of interest.
SOURCE: Shook LM et al. Int J Neonatal Screen. 2020 Jan 31. doi: 10.3390/ijns6010007