For example, mutations in the epigenetic regulatory gene ATRX were shown to cause X-linked mental retardation with α-thalassemia (ATRX syndrome) in ref. 24 and, in early studies, disease-causing mutations were shown to alter the methylation patterns of several repetitive genomic regions including Y-specific satellite and subtelomeric repeats22. This evidence concerns the gene ATRX and thalassemia.