Deletion of FF 4923–4924 (human sequence; equivalent to rabbit FF 4922–4923) in S6 of RyR1, which is associated to fetal akinesia deformation syndrome or FADS, resulted in loss of Ca2+ conductance (Xu et al., 2020), which further supports a role for the Phe clusters in the stability of the pore. The gene discussed is RYR1; the disease is fetal akinesia deformation sequence.