I am a 37 year old woman and I have just discovered that I have a low WBC count (fluctuating within a month between 2.8 and 4.2). I don't have symptoms of anything - I feel perfectly well. In looking at old history it seems that my WBC was low 3.5 years ago as well. Recently I have had several tests with a hematologist, as well as some ultrasounds at the hospital. The only tests that have come back positive are my ANA tests - my pattern being "speckled". However I have just discovered that my 35 year old brother has had low WBC counts for the last 6 years, ranging from 3.2-3.6. And he is also totally healthy. We are both very health conscious and fit. Could this be simply a genetic trait? The other thing we both have in common is that, as small children living in France in the 70s, we both were given the TB shot in our arms. So, when moving to the US, we always showed positive for TB despite not having it. Not sure if that's at all related but thought it was worth mentioning.