Schematic representation of the mutations identified in the

IGnT genes of persons with adult i phenotype.I indicates the coding region of the IGnT gene reported by Bierhuizen et al18 in 1993. ATG and TGA correspond to the enzyme's translation initiation and termination codons, respectively. Mutant alleles identified in the persons with adult i phenotype, designated as Iⁱ¹ andIⁱ², had 1043G→A and 1148G→A nucleotide substitutions, respectively, which predict amino acid alterations of Gly348Glu and Arg383His, respectively.