Biochemical studies on red blood cells from a patient with the Inab phenotype (decay-accelerating factor deficiency).
A 38-year-old Russian woman (KZ) has been identified as the fourth proposita with the Inab blood group phenotype. Like the first two propositi, she has a chronic intestinal disorder and, as shown for the third proposita, her Inab phenotype is demonstrably inherited. KZ's serum contained anti-IFC, which reacted with a red blood cell (RBC) membrane component with an Mr of 70,000, which is decay accelerating factor (DAF). Her RBCs lacked all Cromer-related blood group antigens and DAF. Her RBCs were no more susceptible than normal control RBCs to lysis in acid lysis or in rabbit or human antibody-initiated complement lysis tests. Northern blots of total RNA isolated from KZ's Epstein-Barr virus-transformed lymphoblasts showed a marked reduction of DAF mRNA when compared with normal. Polymerase chain reaction (PCR) amplification of cDNA confirmed this reduced level of DAF mRNA. Sequencing of the PCR product showed a 44-nucleotide deletion in the mRNA close to the short consensus repeats IIIa/IIIb intron/exon boundary. This deletion results in a change in the reading frame that places a termination codon six amino acids after the deletion. The putative translation product would lack a glycosyl phosphatidyl-inositol linkage site and, therefore, would not be membrane-bound in the RBC.
Reid
M E
ME
International Blood Group Reference Laboratory, Bristol, UK.
Mallinson
G
G
Sim
R B
RB
Poole
J
J
Pausch
V
V
Merry
A H
AH
Liew
Y W
YW
Tanner
M J
MJ
D000328:Adult; D000595:Amino Acid Sequence; D000906:Antibodies / Q000378:metabolism; D001483:Base Sequence; D001789:Blood Group Antigens / Q000235:genetics* / Q000276:immunology; D015152:Blotting, Northern; D018958:CD55 Antigens; D003176:Complement C3 / Q000378:metabolism; D003169:Complement Inactivator Proteins / Q000172:deficiency* / Q000235:genetics; D004247:DNA / Q000737:chemistry; D004912:Erythrocytes / Q000737:chemistry / Q000276:immunology* / Q000502:physiology; D005260:Female; D006461:Hemolysis; D006801:Humans; D015151:Immunoblotting; D008565:Membrane Proteins / Q000172:deficiency* / Q000235:genetics; D008969:Molecular Sequence Data; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis / Q000737:chemistry
D000906:Antibodies; D001789:Blood Group Antigens; D018958:CD55 Antigens; D003176:Complement C3; D003169:Complement Inactivator Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D004247:DNA