Purpose: To evaluate the serum fatty acid changes in Chinese patients with Bietti crystalline dystrophy (BCD) in association with CYP4V2 mutation.
Methods: Sixteen Chinese patients with BCD confirmed with CYP4V2 mutation were recruited. Peripheral venous blood was obtained after fasting and serum fatty acid concentrations were measured and compared with those in 13 control subjects. Delta-9-desaturase and Delta-5-desaturase activities were estimated based on serum fatty acid compositions. Serum insulin and glucagon concentrations and their correlations with fatty acid and desaturase activities were also evaluated. Fatty acid concentrations were compared among patients with BCD with different genotypes or phenotypes.
Results: Patients with BCD were found to have a significantly higher concentration of octadecanoic acid (18:0) than that in control subjects (18.28% versus 13.52%, P = 0.007), as well as a lower concentration of octadecadienoic acid (18:1n-9) than that in control subjects (10.97% vs. 14.88%, P = 0.007). The total monounsaturated fatty acid concentration was significantly lower in BCD than in the control (11.82% vs. 15.85%, P = 0.012). The activity of Delta-9-desaturase was also significantly lower in BCD (0.71 vs. 1.14, P = 0.004). Serum glucagon was significantly associated with increased total unsaturated fatty acid and decreased polyunsaturated fatty acid in control subjects but not in patients with BCD. No significant difference in the fatty acid concentration and desaturase activities was found in patients with different genotypes or phenotypes.
Conclusions: Abnormal serum fatty acid composition with reduced Delta-9-desaturase activity was detected in patients with BCD, and the metabolic derangement was unaffected by CYP4V2 mutations. The findings suggest that systemic abnormality in fatty acid metabolism occurs in patients with BCD independent of CYP4V2 genotype.