HELLP Syndrome

Janelle
Does anyone have any insight on this syndrome? 
My mother almost passed due to hellp syndrome and my sister was enduced early to avoid it due to showing early symptoms of it. My doctor says its not hereditary; however, my research and my uncle (who is an obstetrician) tell me otherwise. 
I'm not too concerned about it but I would rather be more prepared than surprised. Any insight helps! 
Thank you