Background information
Dyskerin (NAP57) associates with the chaperone protein Nopp140 and forms a small ribonucleoprotein particle with GAR1 (NOLA1), NHP2 (NOLA2) and Nop10 for the isomerization of uridine to pseudouridine (1). GAR1, NHP2 and dyskerin localize to the dense fibrillar component of the nucleolus and in nuclear Cajal bodies (2). The dyskerin gene maps to chromosome Xq28 (3). Missense mutations in the dyskerin gene interfere with normal nuclear localization of dyskerin and cause Dyskeratosis congenita (DKC) (4). DKC is a rare, X-linked bone marrow disorder characterized by cutaneous hyperpigmentation, dystrophy of the nails, atrophy of the testicles and leukoplakia of the oral mucosa. The GAR1 gene maps to chromosome 4q25 (5,6). The NHP2 gene maps to chromosome 5q35.3 and encodes a 155-amino acid protein (2,7).
