Several hypotheses may explain this trend: (i) a partial loss of CFTR modulatory efficacy over time due to adaptive cellular responses or reduced drug adherence; (ii) an altered metabolic state that influences weight gain and BMI stabilization; and (iii) the progressive nature of cystic fibrosis, which may counterbalance some of the initial therapeutic benefits. The gene discussed is CFTR; the disease is cystic fibrosis.