Sickle cells are shrunk and hardned erythrocytes which in a crisis clump and obstruct blood vessels, causing much pain. It is a hereditary disease with genetic mutation.
Generally, ((Circulatory - Blood|blood cells)) have to do with family identity, there is a passed-on conflict of self-devaluation regarding strength and life force (oxygen transport). 
There is a theory saying that sickle cells [https://www.newscientist.com/article/dn20450-how-sickle-cell-carriers-fend-off-malaria/|developed for the body to handle malaria], so there may have been the root trauma in their ancestors' line. 

!!!Possible approaches
*Physical: hydration and vagotone relaxation to expand the blood vessels where it's needed in a crisis
*Oxytocin can help reduce pain and activate the relaxing vagus nerve [http://www.bloodjournal.org/content/120/21/3236?sso-checked=true] Therefore, caressing and soft touch are beneficial.
*Death or birth of family members are potential triggers; guilt, shame and struggle should be dissolved
*Systemic work, Timeline work, remote healing for the root cause