[1] CIUDAD UNIV MADRID, FDN JIMENEZ DIAZ, CLIN NUESTRA SENORA CONCEPCION, MADRID, SPAIN
[2] HAMMERSMITH HOSP, ROY POSTGRAD MED SCH, LONDON, ENGLAND
[3] UNIV CAMBRIDGE, ADDENBROOKES HOSP,DEPT BIOCHEM,MRC, ABNORMAL HAEMOGLOBIN UNIT,HILLS RD, CAMBRIDGE CB2 2QR, ENGLAND