DKC1 and Intellectual disability: While bone marrow failure combined with reticulate pigmentation is generally considered a defining characteristic of X-linked DC, typically resulting from variants in the DKC1 gene (Heiss et al, 1998), our findings, in conjunction with reported germline variants in POLA1 elsewhere contribute to diverse X-linked manifestations that include skin pigmentation, intellectual disability, hypogonadism, immune deficiency and bone marrow failure (Table 2).