The patient may also have had recent infection with B burgdorferi, as suggested by the results of acute-phase serological testing, which showed a Lyme IgM index (also referred to as an immunoglobulin status ratio, or ISR) of 5.64 by enzyme immunoassay (>1.19 is considered positive) and positive IgM Western blot with 2 of 3 bands present (p23 and p39; both Lyme tests done by Laboratory Corporation of America, Dublin, OH). The gene discussed is CD40LG; the disease is infection.