USB1 and poikiloderma with neutropenia: Discovery of the causative C16orf57 gene by autozygosity mapping and next-generation sequencing of the linkage region on chromosome 166, confirmed that PN is genetically distinct from clinically overlapping entities, in particular Rothmund-Thomson syndrome (OMIM#268400), and allowed the introduction of the genetic test to validate diagnosis and provide patients with the appropriate oncological surveillance7, 8, 9, 10, 11.