Autosomal recessive lamellar ichthyosis (ARLI) belongs to the group of congenital disorders of cornification. It is characterized by a severe and generalized ichthyosis, and other variable cutaneous signs. The human transglutaminase 1 (TGM1) gene was recently found to be the disease-causing gene. Linkage analysis in 23 families (of which 13 were consanguineous) showed that for 10 of them, the disease was linked to the TGM1 gene. A new deleterious mutation introducing a stop codon in the TGM1 reading frame was found. Nevertheless, for the 13 other ARLI families, TGM1 was found to be unlinked to the disease. The present data show that ARLI is genetically heterogeneous and confirm that TGM1 is one of the responsible genes.