Wiskott-Aldrich syndrome: another piece in the puzzle

Diversity of polyproline recognition by EVH1 domains

Enabled/VASP Homology-1 (EVH1) domains function primarily as interaction modules that link signaling proteins by binding to proline-rich sequences. EVH1 domains are ~115 residues in length and adopt the pleckstrin homology (PH) fold. Four different protein families contain EVH1 domains: Ena/VASP, Homer, WASP and SPRED. Except for the SPRED domains, for which no binding partners are known, EVH1 domains use a conserved hydrophobic cleft to bind a four-residue motif containing 2-4 prolines. Conserved aromatic residues, including an invariant tryptophan, create a wedge-shaped groove on the EVH1 surface that matches the triangular profile of a polyproline type II helix. Hydrophobic residues adjacent to the polyproline motif dock into complementary sites on the EVH1 domain to enhance ligand binding specificity. Pseudosymmetry in the polyproline type II helix allows peptide ligands to bind in either of two N-to-C terminal orientations, depending on interactions between sequences flanking the prolines and the EVH1 domain. EVH1 domains also recognize non-proline motifs, as illustrated by the structure of an EVH1:LIM3 complex and the extended EVH1 ligands of the verprolin family.

[Associated diseases and differential diagnostic considerations in childhood atopic eczema]

Atopic eczema (AE) is a chronic inflammatory skin disease which affects 10 to 20% of children and 1 to 3% of adults. AE is usually diagnosed based on standard criteria such as those of Hanifin and Rajka, whereby the age-related variation must be considered. There are numerous other diseases which go along with AE or show a very similar clinical picture and represent important differential diagnostic considerations including parasitic diseases, immunodeficiency, nutritional diseases, certain neoplastic disorders and various corneal abnormalities. Additionally, it is important to consider diseases which can occur in association with AE, such as keratosis pilaris, alopecia areata or sweat disturbances.

Topical tacrolimus is effective against eczema in Wiskott-Aldrich syndrome (WAS)

The Wiskott-Aldrich syndrome is a rare X-linked immunodeficiency characterized by microplatelet thrombocytopenia and eczema. Eczema may be severe and facilitate entry of microorganism into the host.

CONCLUSION

We report for the first time that eczema in infants with WAS can be effectively treated with topical ttacrolimus.