For patients with ATRX syndrome, mutations or the absence of ATRX can alter VNTR sequence lengths, increasing the presence of variant macroH2A at the α-globin locus and leading to transcriptional repression of the hemoglobin α (HBA) gene at the same locus (Pan and Sawalha, 2009; Ratnakumar et al., 2012; Truch et al., 2022; Aguilera and López-Contreras, 2023). This evidence concerns the gene ATRX and alpha thalassemia-X-linked intellectual disability syndrome.