Novel PCSK9 (Proprotein Convertase Subtilisin Kexin Type 9) Variants in Patients With Familial Hypercholesterolemia From Cape Town.

OBJECTIVE: Familial hypercholesterolemia (FH) is characterized by elevated low-density lipoprotein-cholesterol and markedly increased cardiovascular risk. In patients with a genetic diagnosis, low-density lipoprotein receptor (LDLR) mutations account for >90% of cases, apolipoprotein B (APOB) mutations for ≈5% of cases, while proprotein convertase subtilisin kexin type 9 (PCSK9) gain of function mutations are rare (<1% of cases). We aimed to evaluate the functional impact of several novel PCSK9 variants in a cohort of patients with FH by genetic cascade screening and in vitro functionality assays. Approach and Results: Patients with clinically diagnosed FH underwent genetic analysis of LDLR, and if negative, sequential testing of APOB and PCSK9. We analyzed cosegregation of hypercholesterolemia with novel PCSK9 variants. Gain of function status was determined by in silico analyses and validated by in vitro functionality assays. Among 1055 persons with clinical FH, we identified nonsynonymous PCSK9 variants in 27 (2.6%) patients and 7 of these carried one of the 4 previously reported gain of function variants. In the remaining 20 patients with FH, we identified 7 novel PCSK9 variants. The G516V variant (c.1547G>T) was found in 5 index patients and cascade screening identified 15 additional carriers. Low-density lipoprotein-cholesterol levels were higher in these 15 carriers compared with the 27 noncarriers (236±73 versus 124±35 mg/dL; P<0.001). In vitro studies demonstrated the pathogenicity of the G516V variant. CONCLUSIONS: In our study, 1.14% of cases with clinical FH were clearly attributable to pathogenic variants in PCSK9. Pathogenicity is established beyond doubt for the G516V variant.

LDL-cholesterol target achievement in patients with heterozygous familial hypercholesterolemia at Groote Schuur Hospital: Minority at target despite large reductions in LDL-C.

BACKGROUND AND AIMS: Familial hypercholesterolemia (FH) is characterized by markedly increased LDL-cholesterol (LDL-C) and premature cardiovascular disease (CVD). LDL-C lowering is the cornerstone of therapy. The aim of our study was to evaluate LDL-C target achievement and explore reasons for not reaching target in FH patients attending a public-sector lipid clinic at Groote Schuur Hospital in Cape Town, South Africa. METHODS: We reviewed clinical records of patients with genetically confirmed heterozygous FH (heFH) retrospectively. For patients seen after 2013, when new guidelines were published, we determined reasons for use of submaximal therapy. RESULTS: Our study population consisted of 776 adult heFH patients. A substantial proportion (41%) of those younger than 50 years of age had already experienced a cardiovascular event. The mean (±SD) untreated and best achieved LDL-C values during follow up were 8.1 ±â€¯2.1 and 4.0 ±â€¯1.5 mmol/l, respectively. Despite a mean LDL-C reduction of 50%, only 140 (25%) achieved an LDL-C ≤ 3.0 mmol/l. Of the 164 participants with follow up after 2013, 42 did not reach LDL-C < 3.0 mmol/l and did not use maximal therapy (26%). The commonest reasons for not using maximum therapy were statin side-effects (n = 15, 36%) and acceptance by the patient (n = 9, 22%) or the physician (n = 8, 19%) of the control achieved. CONCLUSIONS: The heFH population in Cape Town is characterized by high baseline LDL-C, a high prevalence of CVD at presentation and low rates of achieving an LDL-C target of 3.0 mmol/l.

Efficacy and safety of fluvastatin in children and adolescents with heterozygous familial hypercholesterolaemia.

AIM: To assess whether early initiation of statin therapy for heterozygous familial hypercholesterolaemia favourably affects lipid profiles or vascular morphological changes. METHODS: Children and adolescents aged 10-16 y with heterozygous familial hypercholesterolaemia were administered fluvastatin (80 mg/d) for 2 y in a single-arm two-centre study. Carotid B-mode intima-media thickness (IMT) and M-mode arterial wall stiffness (beta) were recorded. Eighty of the 85 enrolled subjects completed the trial. RESULTS: The median decrease in low-density lipoprotein (LDL) cholesterol from baseline at last study visit was 33.9%; median decreases in total cholesterol, triglycerides and apolipoprotein B were 27.1%, 5.3% and 24.2%, respectively; the median increase in high-density lipoprotein (HDL) cholesterol was 5.3%. Changes in carotid arterial wall thickness and stiffness versus baseline were fractional and statistically non-significant (delta IMT -0.005 mm, 95% CI -0.018 to +0.007 mm, n=83; and delta beta = 0.017, 95% CI -0.219 to +0.253, n=79). Adverse events, all non-serious, were reported by 58 subjects (68.2%); four were suspected to be drug-related. Change in hormone levels and sexual maturation were appropriate for this age group. CONCLUSION: Fluvastatin lowered LDL cholesterol, total cholesterol and apolipoprotein B levels effectively over a prolonged period in children and adolescents with heterozygous familial hypercholesterolaemia. Carotid IMT and wall stiffness remained largely unchanged.