Table 2.

Representatives of genetic polymorphisms in CYP4 genes with clinical impact and their frequencies in different ethnic groups.

Gene	SNP	Location	Mutation	Effect	Frequency a			Functional Effect
					European	African	Asian
CYP4A11	rs1126742	Exon	A > G	Phe330Ser	0.15	0.36	0.25	It was associated with hypertension in white individuals, most probably through decreased production of 20-HETE in the kidney [137].
CYP4F2	rs2108622	Exon	C > T	Val433Met	0.27	0.06	0.26	It reduced the metabolism of vitamin K. Therefore, patients carrying this genetic variant needed a higher dose of warfarin, in order to keep the targeted anticoagulant effect [149,150,151].
CYP4F3	rs4646904	Exon	A > G	Val358Val	0.65	0.35	0.34	It was associated with lung cancer, especially in smokers [30] and ulcerative colitis [158].
CYP4F11	rs200033002	Exon	C > T	Asp315Asn	0	0	0.01	It decreased the metabolism of erythromycin and arachidonic acid compared to the wild type in vitro [37].
CYP4B1	rs3215983	Frameshift variant	AT881–882del	Produces premature stop codon	0.15	ND	0.33	It was reported to increase the risk of bladder cancer, because it has lower capacity to metabolize the carcinogenic compounds [27].
CYP4V2	rs13146272	Exon	C > A	Gln259Lys	0.36	0.4	0.6	It was associated with the risk of deep venous thrombosis and tamoxifen-induced venous thrombosis [162,163,164,165].
CYP4V2	rs199476197	Exon	A > C	His331Pro	0	0	0.0004	It decreased CYP4V2 protein expression and activity toward fatty acid metabolism. Therefore, this genetic variant may cause accumulation of fatty acids in the retina [19,166].
CYP4V2	IVS6-8del17insGC	Intron 6, exon 7	Insertion/deletion	Exon7 del	ND	ND	ND	It causes deletion of exon 7 in the CYP4V2 protein, resulting in a complete loss of CYP4V2 activity. It is the most common mutations in BCD patients [52,99].

^a Data regarding the frequency of genetic variants among different ethnic groups were obtained from Ensemble database. ND, not determined. BCD, Bietti’s crystalline dystrophy.