Thermal stability profiles ofwild-type hALAS2 and XLPP variants indicate that the variants are thermally stabilized. The plotted data are averages of three independent experiments and are fit to equation y = a/(1 +e(−(x-x0)/b). The observed thermal transition temperature (T1/2) values were 48.6°C, 49.9°C, 51.4°C and 52.5°C for wild-type hALAS2 (blue), delAGTG (pink), Q548X (purple) and delAT (green), respectively.