Further support for the view that the FL/IDSPEW/F motif is directly involved in cyclic nucleotide binding is based on the identification of a POPDC1 p.S201F mutation, which has been identified in patients with muscular dystrophy and cardiac arrhythmia phenotypes (Schindler et al. 2016). The gene discussed is POPDC1; the disease is chronic obstructive pulmonary disease.