WDR45 and neurodegeneration with brain iron accumulation 5: BPAN is due to “de novo” mutations in the WDR45 gene causing loss of function of the encoded protein; even though the gene is at the chromosome X, males and females present the same clinical phenotype, which seems to be due to somatic mosaicism or skewing of the X chromosome inactivation (Haack et al., 2012).