Introduction:
We aimed to evaluate the serum level of miRNA-27 (miRNA-27a and miRNA-27b) expression in familial hypercholesterolemia. miRNA-27a/b is a prominent regulator of cholesterol and lipid metabolism and essential miRNA in suppressing cholesterol efflux.

Material and methods:
miRNA-27a/b levels in serum were compared between 39 patients with heterozygous familial hypercholesterolemia (HeFH=20) and homozygous familial hypercholesterolemia (HoFH=19), and 20 healthy subjects. Here, we set out to further characterize the role of miRNA-27a/b in the severity of FH by evaluating the expression of miRNA-27a/b in these subjects. The expression level of miRNA-27a/b was measured using real-time PCR in the three mentioned groups.

Results:
miRNA-27a/b expression in patients with FH (fold change: 2.21±0.69, P=0.001), as well as a subgroup of homozygous FH (fold change: 3±1.19, P=0.001), was significantly higher compared to healthy people. There was a borderline non-significant difference between the heterozygous FH and groups (FC: 1.62±0.46, P=0.059). In the comparison between HoFH and HeFH, the HoFH group had a higher significant level of miRNA-27a/b expression (FC: 1.84±1.19, P=0.009). Furthermore, the expression level was also examined in terms of gender, which was found to be significant in the comparison between the male FH and control groups. However, this difference was not seen between female groups.

Conclusions:
Our research exhibited that miRNA-27a/b has a higher expression in patients with FH than in healthy individuals. Moreover, in comparison with HoFH and HeFH groups, the former had a higher expression level of miRNA-27a/b, which indicates the potential of miRNA-27a/b as a candidate marker for the severity of disease in individuals with FH.