The pathophysiology of sickle cell disease results from cellular defects caused directly by the Hb S mutation interacting with the environment and many other gene products—some known, but most yet unidentified–a typical example of epistasis. How normal tissue perfusion is interrupted is complex and why the phenotype of sickle cell disease differs from patient to patient is poorly understood. Answers to this question will provide additional insight into their biological and functional relationships.

Scientific advances make it feasible to identify additional epistatic genes, which will provide additional insight into their biological and functional relationships.

Discovering differences in phenotypes may change many conclusions reported previously regarding gene functions and interactions.

New methodologies for genetic editing are available
I recently saw at least of couple of presentations showing compelling evidence that KO mice generated with CRISPR (clustered regularly interspaced short palindromic repeat) and Cas (CRISPR-associated) had different phenotypes from the corresponding existing - and widely used - KO (same gene had been knocked-out) using previous methods. This was attributed to the non-specific modification introduced by previously used constructs/methods compared to the most recent precise genetic editing methods using with CRISPER-Cas.