The MYLIP p.N342S polymorphism is associated with response to lipid-lowering therapy in Brazilian patients with familial hypercholesterolemia

Abstract

Background: A previous study reported that the myosin regulatory light chain interacting protein (MYLIP) might serve as a novel therapeutic class for treating dyslipidemia. It contributes to variations in the levels of circulating low-density lipoprotein cholesterol (LDL-C), promoting the degradation of LDL-LDLR, thus limiting absorption. The effect of genetic variation in the MYLIP gene in a disease scenario characterized by mutations in the LDLR gene has not been previously evaluated.

Objective: The aim of this study was to assess the effect of the p.N342S variant on the response to lipid-lowering therapy in Brazilian patients with heterozygous familial hypercholesterolemia (FH).

Patients and methods: A total of 156 patients with heterozygous FH were followed up for 12 months and received lipid-lowering therapy (different doses of atorvastatin with the addition of ezetimibe in over half the patients of each genotype group). Cholesterol data were assessed, and analysis of the MYLIP rs9370867 (p.N342S) genotypes was carried out by melting curve analysis.

Results: Baseline total cholesterol and baseline LDL-C levels were not different between genotypes. After 1 year of treatment, LDL-C responses (expressed as mg/dl and as %) were significantly different among genotypes (AA: -79±68 and -39±27, GA: -60±79 and -27±32, and GG: -30±83 and -15±38; P=0.02 and 0.005, respectively). In addition, FH patients carrying the AA genotype were more likely to achieve LDL-C levels of less than 130 mg/dl after 1 year of treatment (75.0%) compared with patients with the GG and GA genotypes (34.5 and 34.8%, respectively; P=0.001).

Conclusion: Our study indicates that MYLIP p.N342S might be a pharmacogenetic marker for lipid-lowering therapy in patients with FH.

Fig. 1

LDL-C response (mg/dl) according to genotype for the MYLIP polymorphism and the presence of the LDLR mutation. (a) Patients with the LDLR mutation (n=99) and (b) patients without the LDLR mutation (n=57). If the analysis of variance test identified a significant difference, Tukey’s post-hoc test was performed, and values with different superscript letters are significantly different. LDL-C, low-density lipoprotein cholesterol; LDLR, low-density lipoprotein receptor; MYLIP, myosin regulatory light chain interacting protein.

Fig. 2

Frequencies of patients with LDL-C less than 130.0 mg/dl according to genotype for the MYLIP polymorphism and the presence of the LDLR mutation. The χ²-test was performed using a two-row by three-column contingency table. LDL-C, low-density lipoprotein cholesterol; LDLR, low-density lipoprotein receptor; MYLIP, myosin regulatory light chain interacting protein.