Abstract Objectives Assessing sickle cell disease (SCD) phenotype is challenging, hindering progress in care and quality of life. Pain crises are the hallmark of SCD, but no reliable prognostic biomarker exists due to its complex pathophysiology. ADP-ribosylation factor-like protein 13b (ARL13b), a small GTPase localized to primary cilia, is present on sickle RBCs and in plasma, therefore RBC-bound ARL13b may thus predict pain crises in SCD. Methods Blood samples from SCD patients were analyzed for ARL13b on RBCs and soluble ARL13b (sARL13b). Retrospective chart reviews tracked hospitalizations for pain crises within three months before and after enrollment, hemolysis markers (hemoglobin, bilirubin, lactate dehydrogenase), and disease severity indicators (crisis frequency, acute chest syndrome, kidney disease, cerebrovascular accident). Correlations were calculated between ARL13b measures, pain crises, hemolysis, and severity. Results In our pilot study, significant correlations existed between the percentage of RBCs carrying ARL13b measured on the day of enrollment, and the number of pain crisis experienced by the patients during the three months following enrollment (r = 0.3724, p = 0.0301), and clinical severity score (r = 0.5791, p = 0.0003). However, no correlation was found between the percentage of RBCs carrying ARL13b or sARL13b with the number of pain crisis experienced by the patients during the three months prior to enrollment, Hb, bilirubin, or LDH. Conclusion In this exploratory study, ARL13b detected on sickle RBCs provides not only an objective prognostic biomarker of pain crisis, but also a potentially unbiased predictor of SCD severity.
Chauhan et al. (Fri,) studied this question.
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