My understanding is that historically BE was considered a disease primarily found in children as it is commonly associated with CF. So yes, in the CF community being young and diagnosed with BE seems to be common. And of course BE is a risk factor for MAC. If not already done, my suggestion for anyone (female) diagnosed with BE before menopause, and certainly anyone younger than 40, would be to get a complete workup for CF. There is a basic genetic test, a higher level genetic test, and the sweat test. Although I have had both genetic tests (negative), NJH recommends I still get the sweat test which surprised me. There are a number of genetic and autoimmune conditions that can cause BE and while I think everyone who is diagnosed with BE should be evaluated for these conditions certainly the younger one is at diagnosis the more I as a patient would push for a complete workup. @vegita182 if your CT comes back negative for BE, my question would be are there any other structural lung diseases, asthma, COPD (38 seems young for COPD but I don’t have any experience with it). If not, and MAC seems to be standing alone then it’s the proverbial head- scratcher. I have no history of lung infections or lung disease of any kind prior to my recent diagnosis of BE/MAC. I am 58. I suspect, but cannot possibly know, that my MAC infection may have caused my BE. MAC does cause BE and in those without a diagnosis of lung disease prior to a MAC diagnosis there is a bit of a chicken-egg issue. My local ID doctor, who is not an NTM specialist, says one cannot get MAC without structural lung disease, period. I have never heard an NTM specialist say this, quite the opposite; it seems less likely to get MAC in the absence of lung disease but certainly not impossible as my local ID doctor insists. From my reading, it seems there is a lot unknown about the “why” of MAC infection in the small few of us who get infected. Sue recently posted a study showing that globally only 10% of BE patients get infected with MAC. To me, a patient with no medical training whatsoever, that does suggest something more is at play for those of us who get infected. It may be a perfect storm type scenario where multiple risk factors come together; so far, they have not identified a genetic factor underlying MAC infection specifically. It is all hard to say. But a MAC diagnosis at 38 does seem quite young for someone without CF and like you I would want to dig in and see if there is something discernible behind that. I think your CT results will be an important starting point. Attached is some information on NTM that another member @scoop previously posted that gives a great overall discussion on NTM and talks about some of the genetic/autoimmune disorders that may play a part.