Analyses of the transglutaminase 1 gene mutation and ultrastructural characteristics in a Japanese patient with lamellar ichthyosis

We described a Japanese female with lamellar ichthyosis whose transglutamin ase 1 gene (TGM1 gene) was mutated. DNA sequence analysis revealed that the patient had a homozygous mutation, i.e. a point mutation from G to A at nu cleotide 1494 resulting in the substitution of glycine for arginine at codo n 143. Her mother was heterozygous for this mutation. In situ transglutamin ase assay in the patient's skin showed loss of enzyme activity. Ultrastruct ural examination revealed incomplete formation of cornified cell envelopes and electron-dense materials adjacent to plasma membranes. These results su ggest that defective transglutaminase activity caused by homozygous TGM1 ge ne mutation (G143R) results in disruption of cornified envelope assembly an d the clinical phenotype of lamellar ichthyosis. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.