... : Yu t nguy c ca BPTNMT bao gm cỏc yu t bn thõn v yu t mụi trng, bnh xut hin cú s tng tỏc gia hai loi yu t ny 1.4.2.1 Di truyn : Ngi ta thy rng, cú nhiu yu t di truyn lm cho mt ngi tng (hay gim) ... c : 1.4.1 Hen [69], [79] : Hin ti, nguyờn nhõn c th g y bnh hen cha c xỏc nh Ngi ta cho rng, bnh hen l kt qu ca s phi hp nhiu yu t nguy c, gm yu t bn thõn v yu t mụi trng 11 1.4.1.1 Yu t bn thõn ... tng (hay gim) nguy c b BPTNMT Yu t nguy c rừ nht ú l s thiu alpha-1 antitrypsin (mt cht c ch men proteases huyt tng) nng di truyn y l mt bnh him, di truyn theo gene ln, thng xy ngi Bc u Nhng...