Donor splice site mutation in the apolipoprotein (Apo) C-II gene (Apo C-IIHamburg) of a patient with Apo C-II deficiency.
The DNA, RNA, and protein of apo C-II have been analyzed in a patient with apo C-II deficiency (apo C-IIHamburg). Markedly reduced levels of plasma and intrahepatic C-II apolipoprotein were demonstrated by immunoblotting and immunohistochemical analysis. Northern, slot blot, and in situ hybridization studies revealed low levels of a normal-sized apo C-II mRNA. No major rearrangement of the apo C-II gene was detected by Southern blotting. Sequence analysis of apo C-II genomic clones revealed a G-to-C substitution within the donor splice site of intron II. This base substitution resulted in the formation of a new Dde I and loss of a Hph I restriction enzyme cleavage site. Amplification of the mutant sequence by the polymerase chain reaction and digestion with Dde I and Hph I restriction enzymes established that the patient was homozygous for the G-to-C mutation. This is the initial report of the DNA sequence of an abnormal apo C-II gene from a patient with deficiency of apo C-II. We propose that this donor splice site mutation is the primary genetic defect that leads to defective splicing and ultimately to an apo C-II deficiency in this kindred.
Fojo
S S
SS
Molecular Disease Branch, National Heart, Lung and Blood Institute, Bethesda, Maryland 20892.
Beisiegel
U
U
Beil
U
U
Higuchi
K
K
Bojanovski
M
M
Gregg
R E
RE
Greten
H
H
Brewer
H B
HB
D000328:Adult; D053304:Apolipoprotein C-II; D001056:Apolipoproteins C / Q000172:deficiency / Q000235:genetics*; D001483:Base Sequence; D015139:Blotting, Southern; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D005260:Female; D005784:Gene Amplification; D006801:Humans; D009154:Mutation; D012333:RNA, Messenger / Q000032:analysis
D053304:Apolipoprotein C-II; D001056:Apolipoproteins C; D012333:RNA, Messenger; C027908:endodeoxyribonuclease DdeI; D015252:Deoxyribonucleases, Type II Site-Specific; C024412:GGTGA-specific type II deoxyribonucleases