Human butyrylcholinesterase L330I mutation belongs to a fluoride-resistant gene, by expression in human fetal kidney cells

Butyrylcholinesterase genotype and enzyme activity in relation to Gulf War illness: preliminary evidence of gene-exposure interaction from a case-control study of 1991 Gulf War veterans

BACKGROUND

Epidemiologic studies have implicated wartime exposures to acetylcholinesterase (AChE)-inhibiting chemicals as etiologic factors in Gulf War illness (GWI), the multisymptom condition linked to military service in the 1991 Gulf War. It is unclear, however, why some veterans developed GWI while others with similar exposures did not. Genetic variants of the enzyme butyrylcholinesterase (BChE) differ in their capacity for metabolizing AChE-inhibiting chemicals, and may confer differences in biological responses to these compounds. The current study assessed BChE enzyme activity and BChE genotype in 1991 Gulf War veterans to evaluate possible association of this enzyme with GWI.

METHODS

This case-control study evaluated a population-based sample of 304 Gulf War veterans (144 GWI cases, meeting Kansas GWI criteria, and 160 controls). BChE enzyme activity levels and genotype were compared, overall, in GWI cases and controls. Potential differences in risk associated with cholinergic-related exposures in theater were explored using stratified analyses to compare associations between GWI and exposures in BChE genetic and enzyme activity subgroups.

RESULTS

Overall, GWI cases and controls did not differ by mean BChE enzyme activity level or by BChE genotype. However, for the subgroup of Gulf War veterans with less common, generally less active, BChE genotypes (K/K, U/AK, U/A, A/F, AK/F), the association of wartime use of pyridostigmine bromide (PB) with GWI (OR=40.00, p=0.0005) was significantly greater than for veterans with the more common U/U and U/K genotypes (OR=2.68, p=0.0001).

CONCLUSIONS

Study results provide preliminary evidence that military personnel with certain BChE genotypes who used PB during the 1991 Gulf War may have been at particularly high risk for developing GWI. Genetic differences in response to wartime exposures are potentially important factors in GWI etiology and should be further evaluated in conjunction with exposure effects.

Review of human butyrylcholinesterase structure, function, genetic variants, history of use in the clinic, and potential therapeutic uses

Phase I clinical trials have shown that pure human butyrylcholinesterase (BChE) is safe when administered to humans. A potential therapeutic use of BChE is for prevention of nerve agent toxicity. A recombinant mutant of BChE that rapidly inactivates cocaine is being developed as a treatment to help recovering cocaine addicts avoid relapse into drug taking. These clinical applications rely on knowledge of the structure, stability, and properties of BChE, information that is reviewed here. Gene therapy with a vector that sustains expression for a year from a single injection is a promising method for delivering therapeutic quantities of BChE.

Four new mutations in the BCHE gene of human butyrylcholinesterase in a Brazilian blood donor sample

The genetic variation of human butyrylcholinesterase has been associated with height, body mass index, Alzheimer's disease, and response to xenobiotic agents. The present study reports four new mutations, found in the exon 2 of the BCHE gene, in a sample from 3001 Brazilian blood donors. The three nonsynonymous mutations and one synonymous mutation detected are: 223G-->C, G75R; 270A-->C, E90 D; 297T-->G, I99 M; 486T-->C, A162 A, respectively. All these variants are rare: 0.093+/-0.093% for the missense mutations and 0.137+/-0.137% for the synonymous mutation. A table with the 58 non-usual variants of butyrylcholinesterase is also presented.

Butyrylcholinesterase (BCHE) genotyping for post-succinylcholine apnea in an Australian population

BACKGROUND

Measurement of plasma butyrylcholinesterase (BChE) activity and inhibitor-based phenotyping are standard methods for identifying patients who experience post-succinylcholine (SC) apnea attributable to inherited variants of the BChE enzyme. Our aim was to develop PCR-based assays for BCHE mutation detection and implement them for routine diagnostic use at a university teaching hospital.

METHODS

Between 1999 and 2002, we genotyped 65 patients referred after prolonged post-SC apnea. Five BCHE gene mutations were analyzed. Competitive oligo-priming (COP)-PCR was used for flu-1, flu-2, and K-variant and direct DNA sequencing analysis for dibucaine and sil-1 mutations. Additional DNA sequencing of BCHE coding regions was provided when the five-mutation screen was negative or mutation findings were inconsistent with enzyme activity.

RESULTS

Genotyping identified 52 patients with primary hypocholinesterasemia attributable to BCHE mutations, and in 44 individuals the abnormalities were detected by the five-mutation screen (detection rate, 85%). Additional sequencing studies revealed mutations in eight other patients, including five with novel mutations. The most common genotype abnormality was compound homozygous dibucaine and homozygous K-variant mutations. No simple homozygotes were found. Of the remaining 13 patients, 3 had normal BChE activity and gene, and 10 were diagnosed with hypocholinesterasemia unrelated to BCHE gene abnormalities.

CONCLUSION

A five-mutation screen for investigation of post-SC apnea identified BCHE gene abnormalities for 80% of a referral population. Six new BCHE mutations were identified by sequencing studies of 16 additional patients.

Three point mutations of human butyrylcholinesterase in a Japanese family and the alterations of three-dimensional structure

Three different mutations at codons 330 (TTA to ATA), 365 (GGA to AGA) and 515 (CGT to TGT) of human butyrylcholinesterase (hBChE) were identified in a Japanese family. We correlated alterations in in the patient's hBChE activity with possible structural alterations in the three-dimensional structure of hBChE caused by the point mutations. This study was performed using the published computer-generated three-dimensional structure of hBChE based on the structure of acetylcholinesterase. The amino acid substitution at L330I was adjacent to hydrophobic residues that form the channel domain of the active center. This side chain faced the side opposite the active center. The amino acid substitution at G365R was located at the position most remote from the active center, and this substitution site was exposed to the surface of the BChE protein. Alpha-helical structure was present to the active center, and the guanidyl residue of native Arg 515 was hydrogen-bonded to the carboxyl group of Asp 395 in the alpha-helix. These point mutations may cause steric effects on the present patient's hBChE activity. This is the first report of three-dimensional structural analysis performed on the L330I, G365R, and R515C mutations of hBChE.