The LGD vulnerability score is described in https://pubmed.ncbi.nlm.nih.gov/26401017 and is based on relating the observed and expected numbers of ultra-rare LGD variants, where the expected number of ultra-rare LGDs in a gene is computed through a regression to the number of ultra-rare synonymous variants. The score is defined as the cumulative distribution function at the observed number of UR LGD variants of a Poisson distribution with a parameter equal to the expected number of UR LGD variants.