FAMILIALDISEASE is a package performing probability calculations for pedigrees segregating a familial form of disease.
To install within R, devtools::install_github("DudbridgeLab/familialdisease").
Dudbridge F, Brown SJ, Ward L, Wilson SG, Walsh JP. How many cases of disease in a pedigree imply familial disease? Ann Hum Genet 82:109-113.