The fact that we have found association to T1D/AITD for five (PTPN22, IFIH1, CTLA4, INS and C12orf30) previously reported non-HLA genes as well as a novel susceptibility gene, CD247, supports the role for family-based studies in the search for genes involved in complex diseases. This evidence concerns the gene CTLA4 and type 1 diabetes mellitus.