Thus, a total of at least 25 GALNT3 homozygous mutations consisting of 10 missense [3], [14]–[19], 6 nonsense [6], [8], [9], [20], [21] and 9 frameshift/deletion [5]–[8], [16], [17], [22]–[25], (Fig. 1 and Table 1) have been reported in patients with FTC and the hyperostosis-hyperphosphataemia syndrome (HHS), which are allelic variants [2]; 3 homozygous missense FGF23 mutations (Ser71Gly, Met96Thr and Ser129Phe) have been reported in patients with TC [1], [11], [12]; and one homozygous missense KLOTHO mutation (His193Arg) [13] has also been reported in patients with TC. Here, FGF23 is linked to hypotrichosis 1.