Acral self-healing collodion baby: report of a new clinical phenotype caused by a novel TGM1 mutation.

A minority of collodion babies, called 'self-healing collodion babies', heal spontaneously. We describe a novel clinical phenotype of acral self-healing collodion baby caused by a new TGM1 mutation. The proband, born to healthy parents, presented at birth as a collodion baby strictly localized to the extremities. The skin condition returned to normal at the age of 3 weeks. The older sister was born as a generalized collodion baby; the condition then developed into lamellar ichthyosis. Molecular analysis of TGM1 revealed three novel mutations in the family. The proband was compound heterozygous for the p.Val359Met and p.Arg396His mutations, whereas the older sister was compound heterozygous for p.Arg396His and a deletion mutation c.1922_1926+2delGGCCTGT. Structural modelling of the p.Val359Met mutation suggested a minor disruption of the protein structure, whereas a modification of protein-protein interaction was predicted for p.Arg396His. These predictions corroborated the analysis of recombinant transglutaminase (TGase)-1 proteins carrying the p.Val359Met and p.Arg396His mutations. Both showed decreased levels of protein expression: p.Val359Met displayed residual activity (12.8%), while p.Arg396His caused a dramatic loss of activity (3.3%). These observations demonstrate for the first time that TGM1 mutations can be associated with acral self-healing collodion baby, and expand the clinical spectrum of TGase-1 deficiency.

Cloning and characterization of a gut-specific cathepsin L from the aphid Aphis gossypii.

We have characterized proteinase activities in gut extracts from the cotton-melon aphid (Aphis gossypii Glover), an insect feeding strictly on protein-poor phloem. The major, if not exclusive, intestinal proteinases of this aphid are of the cysteine type. A cDNA has been cloned from a gut library and codes for the cysteine proteinase AgCatL, a cathepsin L-like cysteine proteinase. The AgCatL protein shows high sequence similarity with mammalian and some arthropod cathepsin L-like proteinases, but can be reliably distinguished from the secreted (digestive) proteinases identified in other arthropods. AgCatL is widely expressed in aphid intestinal cells. Immunolocalization of AgCatL showed an intense signal at the level of the anterior 'stomach' part of the midgut, and especially at intracellular localization. Although the precise role of AgCatL in aphid midgut physiology is still unclear, this enzyme could be involved in the processing of exogenous ingested polypeptides.