Fig. 2

Overview of cases considering the family history of at least three generations. a Sporadic cases: participants that, according to available information, have no other ID-related case in the family; b Potential familial ID: cases that, according to the questionnaire, could represent hereditary cases; b1 Percentage of the number of additional possibly related cases in a same family (e.g. 41% of the participants considered a potential familial case reported only one additional case in the extended family); c Unlinked ID-related cases: families with probable etiologically unlinked ID-related cases; c1 Percentage of the number of additional unlinked ID-related cases in each family; d Possibly familial, not linked to the participant’s ID: cases of familial ID possibly linked to each other, but not to the cause of the participant’s ID; d1 Percentage of the number of additional cases in a same family; e Family data missing: cases that according to the survey of the questionnaires lacked data to fit into another group (e.g. cases of adoption)