Similarly to CF-PS, diagnosis of PCD is often delayed, with consequent impact on onset of treatment.4,5 The assumption that CF-PS and PCD are milder diseases than CF-PI has falsely reassured us that these patient groups will do reasonably well despite delay in starting appropriate treatment. The findings of Cohen-Cymberknoh et al4 add to the evidence that some patients with PCD have significant morbidity.6,7 The authors unexpectedly found that patients with PCD had substantially lower BMIs than patients with CF-PS or CF-PI (BMI percentiles: PCD, 21; CF-PI, 42; CF-PS, 49). Contrary to patients with CF, their patients with PCD did not receive dietetic input, but care was otherwise similar. From this observational study it is unclear whether the discrepancy in BMI really demonstrates worse nutritional status in patients with PCD than CF, but at face value the data appear clinically relevant and raise an issue that requires further evaluation. Similarly, the data relating to lung function in PCD and CF-PS raises concern for lung disease in these patient groups. Although the cross-sectional data suggest that lung function (FEV1) declines with age most rapidly in patients with CF-PI,4 a significant proportion of teenagers and young adults with PCD and CF-PS had clinically relevant low FEV1. It is worth noting that this study provides further support, that FEV1 correlates well with high-resolution CT imaging evidence of disease severity in CF, but not in PCD, bringing into question the options for regular monitoring of disease progression in this patient group.