CNTN2 and adult T-cell leukemia/lymphoma: ATLL could then be seen as a disease that occurs in people (1) with genetic susceptibility (based on HLA among other genes) to infections, (2) carrying an HTLV-1 strain with dominant HTLV-1 bZIP factor and weak Tax expression, and (3) infected with HTLV-1 mainly via breastfeeding.