RESUMO
Megaloblastic anaemia 1 (MGA1, OMIM 261100) is a rare, autosomal recessive disorder characterized by juvenile megaloblastic anaemia, as well as neurological symptoms that may be the only manifestations. At the cellular level, MGA1 is characterized by selective intestinal vitamin B12 (B12, cobalamin) malabsorption. MGA1 occurs worldwide, but its prevalence is higher in several Middle Eastern countries and Norway, and highest in Finland (0.8/100,000). We previously mapped the MGA1 locus by linkage analysis in Finnish and Norwegian families to a 6-cM region on chromosome 10p12.1 (ref. 8). A functional candidate gene encoding the intrinsic factor (IF)-B12 receptor, cubilin, was recently cloned; the human homologue, CUBN, was mapped to the same region. We have now refined the MGA1 region by linkage disequilibrium (LD) mapping, fine-mapped CUBN and identified two independent disease-specific CUBN mutations in 17 Finnish MGA1 families. Our genetic and molecular data indicate that mutations in CUBN cause MGA1.
Assuntos
Anemia Megaloblástica/genética , Mutação , Receptores de Superfície Celular/genética , Sequência de Aminoácidos , Anemia Megaloblástica/urina , Sequência de Bases , Southern Blotting , Western Blotting , Mapeamento de Sequências Contíguas , Finlândia , Haplótipos , Homozigoto , Humanos , Desequilíbrio de Ligação , Repetições de Microssatélites , Dados de Sequência Molecular , Noruega , Mapeamento Físico do Cromossomo , Polimorfismo Genético , Receptores de Superfície Celular/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Arábia Saudita , Urina/químicaRESUMO
The receptor-binding domains (RBDs) of human and bovine alpha 2-macroglobulin (alpha 2M) have been isolated after limited proteolysis of methylamine-treated alpha 2M with papain. Single crystals of the RBDs have been grown by vapour diffusion. Crystals of human RBD are very thin plates unsuited for data collection. However, crystals of RBD from bovine alpha 2M give diffraction patterns suitable for X-ray analysis, and a complete dataset with a maximum resolution of 2.3 A has been collected with synchrotron radiation at cryogenic temperature. The crystals belong to spacegroup P3(1)21 or P3(2)21 with cell parameters a = b = 106.8 A, c = 72.2 A.