Lipoprotein(a) determination and risk of cardiovascular disease in South African patients with familial hypercholesterolaemia.
OBJECTIVE
A raised plasma level of lipoprotein(a) (Lp(a)) is an established genetic risk factor for coronary heart disease (CHD), particularly in patients with concomitant elevation of low-density lipoprotein (LDL) cholesterol. The current study focused on the comparison of two commercially available Lp(a) assay kits to determine whether differences observed in measured Lp(a) levels could be deemed negligible in CHD risk assessment in familial hypercholesterolaemic (FH) patients.


METHODS
To compare results obtained on duplicate plasma samples using two commercially available Lp(a) measuring kits, the immunoradiometric assay (RIA) and the enzyme-linked immunoabsorbent assay (ELISA).


METHODS
Division of Human Genetics, Department of Obstetrics and Gynaecology, University of Stellenbosch, Tygerberg, South Africa and the Institute for Medical Biology and Human Genetics, University of Innsbruck, Austria.


METHODS
Plasma samples were obtained from 146 family members of 65 molecularly characterised South African FH families for comparative analysis.


RESULTS
Using the RIA method, 34 samples (23%) considered to be in the normal range by the ELISA technique, were placed in the high-risk group (> 30 mg/dl). Only one sample, considered to have a normal Lp(a) level with the RIA method, was categorised by the ELISA technique as high risk.


CONCLUSIONS
Our data demonstrate that measurements of Lp(a) using the RIA method (the only assay available in South Africa at the time of this study) differ significantly from those obtained by the reference ELISA technique, suggesting that misclassification could lead to inaccurate CHD risk assessment. This is an important consideration in Afrikaner FH families, where plasma levels of Lp(a) have been shown to be elevated significantly in FH patients compared with non-FH individuals.
Scholtz
C L
CL
Medical Research Council Cape Heart Group, University of Stellenbosch, Tygerberg, W Cape.
Lingenhel
A
A
Hillermann
R
R
Stander
I A
IA
Kriek
J A
JA
Marais
M P
MP
Odendaal
H J
HJ
Kraft
H G
HG
Utermann
G
G
Kotze
M J
MJ
D000328:Adult; D000368:Aged; D003327:Coronary Disease / Q000097:blood / Q000175:diagnosis / Q000235:genetics*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006801:Humans; D006938:Hyperlipoproteinemia Type II / Q000097:blood / Q000175:diagnosis / Q000235:genetics*; D015592:Immunoradiometric Assay; D017270:Lipoprotein(a) / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011933:Reagent Kits, Diagnostic; D018570:Risk Assessment; D012680:Sensitivity and Specificity
D017270:Lipoprotein(a); D011933:Reagent Kits, Diagnostic