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Identification and functional analysis of Human FMO3 Genetic Variants
Author(s) -
Hines R N,
Koukouritaki S B,
Poch M T,
Henderson M C,
Siddens L K,
Krueger S K,
VanDyke J E,
Romero A M,
Williams D E
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a264-a
Subject(s) - haplotype , single nucleotide polymorphism , genetics , biology , population , snp , intron , gene , microbiology and biotechnology , genotype , medicine , environmental health
Flavin‐containing monooxygenases 3 ( FMO3 ) variants were identified by re‐sequencing 24 Coriell PDR DNA samples. SNP frequencies were determined using DNA from 201 Hispanics (Mexican descent), 201 African‐Americans, & 200 non‐Latino Whites. FMO3 haplotypes were inferred & frequencies estimated using PHASE. Observed haplotypes were introduced into FMO3 /reporter constructs and FMO3 cDNA to assess promoter and catalytic activity, respectively. Forty SNPs were identified, 27 of which were novel. None of the intron SNPs were predicted to affect transcript splicing. Functional analysis of novel E24D & N61K variants with multiple substrates (trimethylamine, methimazole, ethylene thiourea & ranitidine) showed a marginal increase & complete loss of activity, respectively. Seven common upstream haplotypes were inferred in one or more of the study populations. Based on transient expression analysis, haplotype A resulted in an 8‐fold increase in promoter activity whereas a near complete loss of activity was observed with haplotypes D & F. In the Hispanic population haplotype A was linked to two synonymous SNPs & is predicted to result in higher FMO3 expression levels. Finally, 5.4% of the Hispanic population exhibited haplotype 5A, in which the high activity promoter variant is linked to both E158K & E308G, previously shown to reduce enzyme activity. Any in vivo impact of these two structural variants may be minimized by the high promoter activity in this population. (Supported by PHS grants CA053106 & HL038650)