The phrase "familial form" means something related to or characteristic of a family. It describes things that are specific to family relationships or resemble traits found within a family. Full definition
Because scientists have had difficulty analyzing these interactions, most research has focused on rare familial forms of the disease. (sciencedaily.com)
Presenilins 1 and 2 (PS1 and PS2) are the catalytic subunits of the γ - secretase complex, and genes encoding mutant PS1 and PS2 variants cause familial forms of Alzheimer's disease. (semanticscholar.org)
In the study, the researchers transformed iPS cells from two different people with familial forms of ALS, one caused by mutations in the SOD1 gene and the other by mutations in the VAPB gene. (alsa.org)