Lamellar ichthyosis (LI) is an autosomal recessive disorder of cornificatio
n. Mutations in the transglutaminase 1 gene (TGM1) have been identified in
several families with this disorder. We analyzed two unrelated families wit
h offspring affected with LI. Family 1 included affected monozygotic twins,
in which a homozygous G-to-T transversion was identified in exon 6 at amin
o acid residue R315L. This mutation was also identified in the unaffected m
other. In family 2, which consisted of one affected infant, a T-to-G transv
ersion in exon 8 resulted in a change of phenylalanine to valine, F400V, an
d a C-to-T transition in exon 4 resulted in a change of proline to leucine,
P248L. In this family, the mutation F400V was found in the unaffected fath
er, and the mutation P248L was identified in the unaffected mother. These f
indings extend the growing body of literature documenting mutations in the
TGM1 gene as the molecular basis of certain cases of lamellar ichthyosis.