In genetic studies, the absence of TKFC catalytic activities in biallelic mutants of isoform X6 has been related to several phenotypes including cataracts and multi system disease, developmental delay, liver dysfunction, microcytic anemia, fatal cardiomyopathy [24], hypotrichosis with loose anagen hairs [23], and an isolated, complex primary immunodeficiency [25]. This evidence concerns the gene TKFC and microcytic anemia.