Incidence and Laboratory Differentiation of Hb S/D-Punjab and Hb S/Korle-Bu in Newborn Screening in Minas Gerais, Brazil: A 10-Year Prospective Study

HbSD hemoglobinopathy is considered a rare condition worldwide, and the FSD pattern detected by isoelectric focusing (IEF) during newborn screening is uncommon. Previous studies have demonstrated that newborns with this pattern may present distinct clinical outcomes depending on the associated variant. This study aimed to estimate the incidence of Hb S/D-Punjab and Hb S/Korle-Bu in Minas Gerais, Brazil, and to characterize their laboratory profiles using IEF and high-performance liquid chromatography (HPLC). Between January 2015 and December 2024, 2,177,336 newborns were screened. Ten cases of Hb S/D-Punjab and nine of Hb S/Korle-Bu were identified, corresponding to an overall incidence of the FSD pattern in IEF of 1:114,000 newborns. Both genotypes exhibited the FSD pattern by IEF; however, HbD-Punjab showed slightly more anodic migration than Hb Korle-Bu. By HPLC, HbD-Punjab eluted in the HbD window, whereas Hb Korle-Bu eluted in the HbA2/E window, allowing clear differentiation. Given the distinct clinical implications of these genotypes, accurate identification during newborn screening is essential to ensure appropriate clinical follow-up.