Genetic predisposition to breath-hold diving-induced hemoptysis: Preliminary study.

Introduction: Breath-hold diving-induced hemoptysis (BH-DIH) has been reported in about 25% breath-hold divers (BHD) and is characterized by dyspnea, coughing, hemoptysis and chest pain. We investigated whether eNOS G894T, eNOS T786C and ACE insertion/deletion I/D genetic variants, are possible BH-DIH risk factors.
Methods: 108 experienced healthy instructor BHDs with the same minimum requirements (102 male, six female; mean age 43.90 ± 7.49) were studied. We looked for different eNOS G894T, eNOS T786C and ACE insertion/ deletion genetic variants between BH-DIH-positive and BH-DIH-negative subjects to identify the variants most frequently associated with BH-DIH.
Results: At least one BH-DIH episode was reported by 22.2% of subjects, while 77.7% never reported BH-DIH. The majority of BH-DIH-positive subjects showed eNOS G894T (p = 0.001) and eNOS-T786C (p = 0.001) genotype "TT" (high-risk profile). Prevalence of BH-DIH was higher in subjects with eNOS G894T TT genotype (50%) than in subjects with GT (9.5%, p < 0.001) and GG (24%, (p = 0.0002) genotype (low-risk profile). Similar results were observed for eNOS T786C: BH-DIH prevalence was higher in the TT genotype (41.2%) group than in the CT (15.4%, p < 0.001) and CC genotype (9.1%, p < 0.001) groups. BH-DIH prevalence was significantly higher in subjects showing ACE ID genotype (34.5%) than II (0%, p < 0.001) and DD (10.5%, p = 0.0002). Of the ACE "II" genotype group, 100% never developed BH-DIH.
Discussion: eNOS-G894T, eNOS-T786C and ACE influence NO availability and regulation of peripheral vascular tone and blood flow. Different genetic variants of eNOS-G894T, eNOS-T786C and ACE appear significantly related to the probability to develop BH-DIH (p < 0.001).