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AFRICA
Cardiovascular Journal of Africa • ABSTRACTS – SA HEART
®
CONGRESS 2019
S32
An investigation into the PCSK9 gene polymorphism E670G and the risk of coronary artery disease in the South African
black population
Nitien Naran*, Sean-Michael Bhika
#
, Ruth Jali
#
, Nqoba Tsabedze
†
and Nigel Crowther*
*NHLS, Johannesburg, South Africa.
#
University of the Witwatersrand, Johannesburg, South Africa.
†
Division Of Cardiology, Department of Internal Medicine,
Faculty of Health Sciences, Charlotte Maxeke Johannesburg Academic Hospital, University of the Witwatersrand, Johannesburg, South Africa
Introduction:
Proprotein convertase, PCSK9, promotes LDL receptor (LDLR) degradation. Gain-of–function mutations in PCSK9 reduce LDLR expression,
which decreases cellular uptake of LDL resulting in elevated serum LDL concentrations. The G allele of the E670G polymorphism in PCSK9 is associated with
higher LDL levels and coronary artery disease (CAD). The G variant may increase the affinity of PCSK9 for LDLR. The prevalence of CAD is increasing in South
Africa, however, no data exists on the disease-association of E670G in the local population. Therefore, our aim was to investigate the association of the E670G
polymorphism with CAD in a South African black population.
Methods:
African CAD cases (n=71) were recruited from the Charlotte Maxeke Johannesburg Academic Hospital cardiac clinic. A convenience sample of
African control participants, with no history of CAD (n=111), was also recruited. Fasting serum lipid concentrations were measured using routine laboratory
methods. Genotyping of the E670G polymorphism was performed using a standard RFLP-based PCR method.
Results:
The percentage of subjects carrying the E670G GG or AG genotypes (G carriers) was higher in cases (69.0%) than controls (50.4%; p=0.01). When
comparing G carriers to those with the AA genotype (non G carriers), there were no differences in LDL (p=0.62), total cholesterol (p=0.12) or HDL (p=0.49)
levels but triglyceride levels were higher in the G carriers (p=0.003). Logistic regression demonstrated that G carriers had an odds ratio (with 95% CIs) for CAD
of 2.19 (1.16, 4.11) (p=0.01) compared to non G carriers.
Conclusion:
The G allele of the E670G polymorphism in the PCSK9 gene is associated with a greater than 2-fold risk of CAD in black African participants. It is
possible that this effect is mediated by the modulation of lipid levels by PCSK9, however, this hypothesis can only be confirmed in
cases where recent coronary events have not been treated with lipid-lowering agents.
An investigation of the prevalence of a lectin-like oxidised low density lipoprotein receptor: 1 (LOX-1) gene polymorphism
(G501C) in patients with coronary artery disease in South Africa
Nitien Naran*, Gerrit Maasdorp*, Nqoba Tsabedze# and Nigel Crowther*
*NHLS, Johannesburg, South Africa.
#
Division Of Cardiology, Department of Internal Medicine, Faculty of Health Sciences, Charlotte Maxeke Johannesburg
Academic Hospital, University of the Witwatersrand, Johannesburg, South Africa
Introduction:
Coronary artery disease (CAD) is a multifactorial disorder. Epidemiological studies have shown that the incidence of CAD has been increasing
markedly in developing countries. Several studies have attempted to identify candidate genes that may be associated with CAD. One such gene is the
oxidised low-density lipoprotein receptor-1 (LOX-1) gene. This receptor is responsible for the binding, internalisation and degradation of ox-LDL in endothelial
cells. A single nucleotide polymorphism (G501C) of the LOX-1 gene results in a non-conservative amino acid dimorphism (Lys/Asn) and studies have shown
a lower frequency of the C allele (CC/GC) in patients having CAD. As yet, there is no data on the LOX-1 G501C gene polymorphism in the South African
population. Therefore, the aim of this study was to investigate the prevalence of different G501C genotypes in CAD patients and controls in a black South
African population.
Methods:
A total of 47 patients with confirmed CAD were recruited from a local cardiac clinic and 39 control subjects with no history of heart disease were
recruited by convenience sampling. Anthropometric data were measured and venous blood samples collected for serum lipid profile. Venous blood in EDTA
was collected for DNA extraction and RFLP-based PCR was used to determine the LOX-1 G501C genotypes.
Results:
There was a lower frequency of C allele carriers i.e. CC or GC in CAD (40.4%) than non-CAD (51.3%) subjects, but this association did not reach
statistical significance (p=0.319). In addition, C allele carriers tended to have lower serum LDL cholesterol levels than those with the GG genotype [median
(interquartile range): 2.35 (1.73, 3.56) vs. 2.73 (2.29, 3.52) mmol/L; p=0.086].
Conclusion:
The C allele is associated with a lower prevalence of CAD and a less atherogenic lipid profile. However, these differences did not reach statistical
significance and must be confirmed using a larger sample size.
Initiating the first rheumatic heart disease clinic for children and adolescents in Cameroon
Yanwou Nguemnang Nathan Yves and Njedock Nelson
Faculty of Medicine and Biomedical Sciences, University of Yaounde, Yaounde, Cameroon
Introduction:
Rheumatic heart disease (RHD) remains the major cause of heart failure, stroke and death among African children. Secondary prophylaxis is a
key solution to slow disease progression. A pilot RHD clinic was established in Yaoundé, Cameroon, to increase the adherence to secondary prophylaxis and
build a prospective registry to facilitate a follow-up amenable to the assessment of outcomes.
Methods:
The echocardiography registers of 2 centres were accessed. Children diagnosed with RHD, between 2015 and 2018, were contacted and invited to
the launch of the RHD clinic. Sociodemographic and clinical data were collected progressively for the registry during a monthly appointment.
Results:
From the 1 200 patients included in the echo registers, 70 had confirmed RHD. Overall, 23 patients were included in the registry, 16 patients were
female, the mean age at diagnosis was 11.2 years (4 - 23) and 87% lived in urban Yaoundé. Adherence to secondary prophylaxis increased from 31% at the
beginning to 86% at 6 months. Two patients had severe lesions which required surgery. No patient was completely assessed for complications.
Conclusion:
Adherence to secondary prophylaxis for patients suffering from RHD is very challenging. A close follow-up and patient education programme is
important to achieve adequate adherence. Resources are needed to build sustainable and complete registers.