FIGURE 1.

DNA-sequencing has revealed that the disease-associated insertions contain at least one breakpoint located toward the center of the 180 bp quasi-palindrome at Xq27.1. Illustration depicts the hairpin loop that is predicted to form at the center of the palindrome. Colored lines denote the position of the breakpoints for the insertions associated with hypoparathyroidism (Taylor et al., 2015), CMTX3 (Brewer et al., 2016), hypertrichosis^1,2 (Zhu et al., 2011), hypertrichosis³ (DeStefano et al., 2013), XX male sex reversal (Haines et al., 2015), ptosis (Bunyan et al., 2014), Plott syndrome (Boschann et al., 2022), and a rare undiagnosed phenotype characterised by limb abnormalities and everted lips (Si et al., 2019). This schematic also depicts the breakpoints for a de novo insertion classified as a “variant of unknown significance” in a patient with congenital abnormalities (Middelkamp et al., 2019). Note that some of the insertions display additional breakpoints located outside this region (Zhu et al., 2011; Taylor et al., 2015; Boschann et al., 2022); see Table 1 for details. Figure has been adapted from Brewer et al. (2016) (Figure 4), originally published in PLOS Genetics, to incorporate additional disease-associated insertions that have been identified in recent years. Image created with BioRender.com.