Haplotype and functional analysis of four flavin-containing monooxygenase isoform 2 (FMO2) polymorphisms in Hispanics

Pharmacogenet Genomics. 2005 Apr;15(4):245-56. doi: 10.1097/01213011-200504000-00008.


Objectives: Previous work defined two flavin-containing monooxygenase 2 (FMO2) alleles. The major allele, FMO2*2 (g.23,238C>T), encodes truncated inactive protein (p.X472) whereas the minor allele, FMO2*1, present in African- and Hispanic-American populations, encodes active protein (p.Q472). Recently, four common (27 to 51% incidence) FMO2 single nucleotide polymorphisms (SNPs) were detected in African-Americans (N=50); they encode the following protein variants: p.71Ddup, p.V113fs, p.S195L and p.N413 K. Our objectives were to: (1) determine the incidence of these SNPs in 29 Hispanic individuals previously genotyped as g.23,238C (p.Q472) and 124 previously genotyped as homozygous g.23,238 T (p.X472); (2) determine FMO2 haplotypes in this population; and (3) assess the functional impact of SNPs in expressed proteins.

Methods: SNPs were detected via allele-specific oligonucleotide amplification coupled with real-time or electrophoretic product detection, or single strand conformation polymorphism.

Results: The g.7,700_7,702dupGAC SNP (p.71Ddup) was absent. The remaining SNPs were present but, except for g.13,732C>T (p.S195L), were less common in the current Hispanic study population versus the previously described African-Americans. Only expressed p.N413 K was as active as p.Q472, as determined by methimazole- and ethylenethiourea-dependent oxidation. Haplotype determination demonstrated that the g.10,951delG (p.V113fs), g.13,732C>T (p.S195L) and g.22,060T>G (p.N413 K) variants segregated with g.23,238C>T (p.X472).

Conclusions: SNPs would not alter FMO2 activity in individuals possessing at least one FMO2*1 allele. It is likely that these SNPs will segregate similarly in African-American populations. Therefore, estimates that 26% of African-Americans and 2-7% of Hispanic-Americans have at least one FMO2*1 allele should closely reflect the percentages producing active FMO2 protein.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alleles
  • Antithyroid Agents / pharmacology
  • DNA Primers / chemistry
  • DNA, Complementary / metabolism
  • Ethylenethiourea / pharmacology
  • Genetic Vectors
  • Genotype
  • Haplotypes*
  • Hispanic or Latino
  • Homozygote
  • Humans
  • Methimazole / pharmacology
  • Mutagenesis, Site-Directed
  • Mutation
  • Oxygenases / genetics*
  • Pharmacogenetics
  • Polymerase Chain Reaction
  • Polymorphism, Genetic
  • Polymorphism, Single Nucleotide
  • Polymorphism, Single-Stranded Conformational
  • Temperature


  • Antithyroid Agents
  • DNA Primers
  • DNA, Complementary
  • Ethylenethiourea
  • Methimazole
  • Oxygenases
  • dimethylaniline monooxygenase (N-oxide forming)