CRMS/CFSPID subjects carrying D1152H CFTR variant: can the second variant be a predictor of disease development?

Background: There are no predictive factors of evolution of cystic fibrosis (CF) screen positive inconclusive diagnosis subjects (CFSPIDs). Aim: to define the role of the second CFTR variant as a predictive factor of disease evolution in CFSPIDs carrying the D1152H variant. Methods: We retrospectively evaluated clinical characteristics and outcome of CFSPIDs carrying the D1152H variant followed at five Italian CF centers. CFSPIDs were divided in two groups: Group A: compound heterozygous for D1152H and a CF-causing variant; Group B: compound heterozygous for D1152H and a: (i) non CF-causing variant, (ii) variant with varying clinical consequences, or (iii) variant with unknown significance. The variants were classified according to CFTR2 mutation database. Results:We enrolled 43 CFSPIDs with at least one D1152H variant: 28 (65.1%) were classified in the group A, and 15 (34.9%) in the Group B. CFSPIDs of group A had the first IRT significantly higher compared to those of group B (p < 0.05) and had a more severe clinical outcome during the follow-up. At the end of the study period, after a mean follow-up of 40.6 months (range 6–91.6), 4 (9.3%) out of 43 CFSPIDs progressed to CFTR-RD or CF. All these subjects were in the group A. Conclusions: The genetic profile could help predict the risk of disease evolution in CFSPIDs carrying D1152H, revealing the subjects that need a more frequent follow-up.