SH2D1A and X-linked lymphoproliferative syndrome: For patient BC156, diagnosed with Burkitt lymphoma and carrying a hemizygous intragenic deletion of SH2D1A (diagnostic for X-linked lymphoproliferative syndrome type 1, OMIM #308240), immunological surveillance was initiated and allogeneic stem cell transplantation was planned as further treatment due to risk for hemophagocytic lymphohistiocytosis and for a new or second malignancy.