USH2A and Global developmental delay: Although subsequent studies in peripheral blood could not demonstrate skewed inactivation of the X chromosome, this deletion, together with the presence of biallelic USH2A (MIM *608400) variants, may explain the phenotype of the patient suffering from early onset retinitis pigmentosa (RP), global developmental delay, tip-toe gait, talipes equinovarus, and dysmorphic features (Supplementary Fig. S4).