CAMKK2 and poikiloderma with neutropenia: Meanwhile, genetic studies made assumptions on single-nucleotide polymorphisms, i.e., in gene CAMKK2, on position rs28445017, or in MTND2*LHON-4917G but possibly also others, being associated with development of PN but this needs further clarification (Canter et al. 2008; Wadley et al. 2015; Goullee et al. 2016; Hendry et al. 2016; Gaff et al. 2018).