The Ras and Rab interactor 2 (RIN2) protein, a guanine nucleotide exchange factor for the early endocytic pathway regulator RAB5 [16], has been found to be at the heart of two related connective tissue disorders, namely macrocephaly, alopecia, cutis laxa and scoliosis (MACS) syndrome and the RIN2 syndrome [17,18]. This evidence concerns the gene RIN2 and RIN2 syndrome.