A Report of Two Cases of TGM1 Mutations in Iranian Patients with Lamelar Ichthyosis

Autosomal Recessive Congenital Ichthyosis (ARCI) is a rare, heterogenous keratinization disorder of the skin, classically divided into two clinical subtypes, Lamellar Ichthyosis (LI) and Nonbullous Congenital Ichthyosi-formis Erythroderma (NCIE). Lamellar Ichtyosis is caused by mutations in the TGM1 gene that encodes transglutaminase 1 enzyme, which is critical for the assembly of the cornified cell envelope in terminally differentiating keratinocytes. TGM1 is a complex enzyme existing as both cytosolic and membrane-bound forms.

Moreover, TGM1 is proteolytically processed, and the major functionally active form consists of a membrane-bound 67/33/10-kDa complex with a myristoylated and palmitoylated amino-terminal 10-kDa membrane anchorage fragment. In this study, all 14 coding exons of TGM1 gene were investigated using PCRsequencing method in three Iranian patients with different phenotypes which are often caused by homozygote or compound heterozygote mutations and a homozygote mutation (G218S) in exon 4 and three heterozygote mutations (R37K, D58N, D86N) in exon 2 were observed. The mutation (D86N) was seen in two patients simultaneously.