Sex Differences in Familial Hypercholesterolemia

Lipoprotein Metabolism, Dyslipidemia, and Lipid-Lowering Therapy in Women: A Comprehensive Review

Lipid-lowering therapy (LLT) is a cornerstone of atherosclerotic cardiovascular disease prevention. Although LLT might lead to different reductions in low-density lipoprotein cholesterol (LDL-C) levels in women and men, LLT diminishes cardiovascular risk equally effectively in both sexes. Despite similar LLT efficacy, the use of high-intensity statins, ezetimibe, and proprotein convertase subtilisin/kexin type 9 inhibitors is lower in women compared to men. Women achieve the guideline-recommended LDL-C levels less often than men. Greater cholesterol burden is particularly prominent in women with familial hypercholesterolemia. In clinical practice, women and men with dyslipidemia present with different cardiovascular risk profiles and disease manifestations. The concentrations of LDL-C, lipoprotein(a), and other blood lipids differ between women and men over a lifetime. Dissimilar levels of LLT target molecules partially result from sex-specific hormonal and genetic determinants of lipoprotein metabolism. Hence, to evaluate a potential need for sex-specific LLT, this comprehensive review (i) describes the impact of sex on lipoprotein metabolism and lipid profile, (ii) highlights sex differences in cardiovascular risk among patients with dyslipidemia, (iii) presents recent, up-to-date clinical trial and real-world data on LLT efficacy and safety in women, and (iv) discusses the diverse medical needs of women and men with dyslipidemia and increased cardiovascular risk.

Special Aspects of Cholesterol Metabolism in Women

BACKGROUND

Cardiovascular diseases due to arteriosclerosis are the most common causes of death and disability in both men and women. Hypercholesterolemia, a treatable risk factor, is often detected after a delay in women, and then inadequately treated. It is, therefore, important to know the sex-specific aspects of cholesterol metabolism and to address them specifically.

METHODS

We conducted a selective literature search in PubMed with particular attention to current guidelines.

RESULTS

In the population as a whole, the age-associated rise in serum cholesterol levels occurs approximately 10 years later in women than in men. Women are exposed to a higher cholesterol load than men at the beginning of their lives, and especially after menopause. This is correlated with a later, but nonetheless clinically relevant rise in the incidence of myocardial infarction in older women. Because women's LDL cholesterol and lipoprotein(a) levels rise after menopause, their lipid profiles should be re-evaluated at this time. Moreover, conditions that are specific to women such as polycystic ovary syndrome, contraception, and especially the phases of life-such as planning to become pregnant, pregnancy, and breastfeeding-need to be considered for both diagnostic and therapeutic purposes. Sex-specific differences and cholesterolassociated risks are particularly pronounced in women with familial hypercholesterolemia (prevalence 1:250).

CONCLUSION

Lowering high cholesterol levels, especially in postmenopausal women, may prevent the development of cardiovascular diseases.

Dyslipidaemia management in pregnant patients: a 2024 update

Over several decades, the approach to treating dyslipidaemias during pregnancy remains essentially unchanged. The lack of advancement in this field is mostly related to the fact that we lack clinical trials of pregnant patients both with available as well as new therapies. While there are numerous novel therapies developed for non-pregnant patients, there are still many limitations in dyslipidaemia treatment during pregnancy. Besides pharmacotherapy and careful clinical assessment, the initiation of behavioural modifications as well as pre-conception management is very important. Among the various lipid-lowering medications, bile acid sequestrants are the only ones officially approved for treating dyslipidaemia in pregnancy. Ezetimibe and fenofibrate can be considered if their benefits outweigh potential risks. Statins are still considered contraindicated, primarily due to animal studies and human case reports. However, recent systematic reviews and meta-analyses as well as data on familial hypercholesterolaemia (FH) in pregnant patients have indicated that their use may not be harmful and could even be beneficial in certain selected cases. This is especially relevant for pregnant patients at very high cardiovascular risk, such as those who have already experienced an acute cardiovascular event or have homozygous or severe forms of heterozygous FH. In these cases, the decision to continue therapy during pregnancy should weigh the potential risks of discontinuation. Bempedoic acid, olezarsen, evinacumab, evolocumab and alirocumab, and inclisiran are options to consider just before and after pregnancy is completed. In conclusion, decisions regarding lipid-lowering therapy for pregnant patients should be personalized. Despite the challenges in designing and conducting studies in pregnant women, there is a strong need to establish the safety and efficacy of dyslipidaemia treatment during pregnancy.

Recapitulating familial hypercholesterolemia in a mouse model by knock-in patient-specific LDLR mutation

Familial hypercholesterolemia (FH) is one of the most prevalent monogenetic disorders leading to cardiovascular disease (CVD) worldwide. Mutations in Ldlr, encoding a membrane-spanning protein, account for the majority of FH cases. No effective and safe clinical treatments are available for FH. Adenine base editor (ABE)-mediated molecular therapy is a promising therapeutic strategy to treat genetic diseases caused by point mutations, with evidence of successful treatment in mouse disease models. However, due to the differences in the genomes between mice and humans, ABE with specific sgRNA, a key gene correction component, cannot be directly used to treat FH patients. Thus, we generated a knock-in mouse model harboring the partial patient-specific fragment and including the Ldlr W490X mutation. LdlrW490X/W490X mice recapitulated cholesterol metabolic disorder and clinical manifestations of atherosclerosis associated with FH patients, including high plasma low-density lipoprotein cholesterol levels and lipid deposition in aortic vessels. Additionally, we showed that the mutant Ldlr gene could be repaired using ABE with the cellular model. Taken together, these results pave the way for ABE-mediated molecular therapy for FH.

Sex differences in the presentation, treatment and outcomes of patients with homozygous familial hypercholesterolemia

BACKGROUND

Homozygous familial hypercholesterolemia (HoFH) is a rare, autosomal semi-dominant lipid metabolism disorder characterized by extremely high low-density lipoprotein cholesterol (LDL-C) levels and premature cardiovascular disease. The objective of this study was to investigate sex-differences in the treatment and outcomes of patients with HoFH.

METHODS

We examined clinical characteristics, lipid-lowering therapy (LLT), and cardiovascular events using descriptive statistics of patients in the Canadian HoFH registry. Major adverse cardiovascular events (MACE) were defined as the composite of cardiovascular death, non-fatal myocardial infarction, and stroke. Sex differences between continuous and categorical variables were analyzed using Mann-Whitney U test and Fisher's Exact test, respectively.

RESULTS

This study included 48 patients (27 (56%) female). The median age at diagnosis in females was 14.0 (interquartile range (IQR) 9.0-30.0) and in males was 8.0 (IQR 2.0-23.0) (p = 0.07). Baseline clinical characteristics were comparable between both sexes. The median baseline LDL-C was 12.7 mmol/L (10.0-18.3) in females and 15.3 (10.5-20.0) in males (p = 0.51). Follow up LDL-C levels were 7.6 mmol/L (IQR 4.8-11.0) in females and 6.3 (IQR 4.6-7.5) in males (p = 0.1). Most patients were taking 3 or more LLTs, with comparable proportions in both sexes (p = 0.26). Apheresis was similar in both sexes, 14 (51.8%) vs. 10 (47.6%) (p = 0.2). Over a mean of 10 years of follow-up, MACE occurred in 3 females (11.1%) and 4 males (19.1%) (p = 0.2).

CONCLUSION

Lipid levels and treatment were similar between sexes. MACE occurred in similar proportions between sexes, indicating that HoFH offsets the inherently lower cardiovascular risk in pre-menopausal females. Further investigation into sex-differences in HoFH in larger sample sizes is warranted.