Familial occurrence of LGL leukaemia

Summary. The aetiology of LGL leukaemia is now known: however, we recently detected HTLV‐II from such a patient. We describe here the occurrence of LGL leukaemia in a mother and her son. Serum from the son reacted to HTLV‐I/II gag proteins, but not to recombinant HTLV‐I env protein p21e; serum from the mother was negative. PCR analyses in both patients were negative for pX and pol sequences shared by HTLV‐I/II and also for specific gag sequences of HTLV‐I and HTLV‐II. These data show that familial cases of LGL leukaemia are not associated with prototypical HTLV‐I or HTLV‐II infection.