The association between a genetic polymorphism of coproporphyrinogen oxidase, dental mercury exposure and neurobehavioral response in humans

Diana Echeverria, James S. Woods, Nicholas J. Heyer, Diane Rohlman, Federico M. Farin, Tingting Li, Claire E. Garabedian

Research output: Contribution to journalArticle

66 Citations (Scopus)

Abstract

We previously described a polymorphism in exon 4 of the gene encoding the heme biosynthetic pathway enzyme, coproporphyrinogen oxidase (CPOX4), which significantly modifies the effect of mercury exposure on urinary porphyrin excretion in humans. Here, we examined potential consequences of this polymorphism ("CPOX4") on performance within neurobehavioral domains, symptoms, and mood that are known to be affected by elemental mercury (Hg°) exposure in human subjects. A behavioral test battery was administered on the day of urine and buccal cell collections for 194 male dentists (DDs) and 233 female dental assistants (DAs) occupationally exposed to Hg° for an average of 19 and 10 years, respectively. Subjects had no history of health disorders and were employed for a minimum of 5 years in the dental profession. Respective mean urinary mercury (HgU) levels in DDs and DAs were 3.32 (4.87) μg/l and 1.98 (2.29) μg/l. Corresponding indices of chronic occupational Hg° exposure, weighted for historical exposure, were 27.1 (20.6) and 15.2 (12.3). The frequencies of the homogygous common (A/A), heterozygous (A/C), and homozygous polymorphic (C/C) genotypes were 75%, 23% and 2% for DDs and 73%, 25%, and 2% for DAs, respectively. DDs and DAs were evaluated separately. Regression analyses controlled for age, premorbid intelligence, alcohol consumption, and education. Statistically significant associations with HgU (p <0.05) were found for nine measures among DDs (BEES Digit Span Forward and Backward, WMS-R Visual ReproductionN Correct, BEES Symbol DigitRate, BEES Finger TappingDom/Non-dom, and Alternate Partialed, Hand SteadinessFactor1, and BEES Tracking), and eight measures among DAs (BEES Digit SpanForward, BEES Symbol DigitRate, BEES Pattern Discrimination Rate, BEES Trailmaking B, BEES Finger Tapping Dom/Non-dom, and Alternate Partialed, Hand Steadiness Factor1, and Vibration SensitivityHits). CPOX4 status was associated with four measures in DDs (BEES Spatial SpanForward, BEES Pattern MemoryN Correct, BEES Symbol DigitRate, and BEES VigilanceHit) and five measures in DAs (BEES Digit Span Forward, WMS-R Visual ReproductionsN Correct, BEES Symbol DigitRate, BEES Simple and Choice Reaction TimeMove. Both groups experienced an additive effect (no interaction term) for HgU and the CPOX4 polymorphisms on the DigitRate whereas DAs also had additive effects for BEES Digit SpanForward and for Beck's Depression factor 'Worthlessness'. These exploratory findings suggest that the CPOX4 polymorphism may affect susceptibility for specific neurobehavioral functions associated with mercury exposure in human subjects.

Original languageEnglish (US)
Pages (from-to)39-48
Number of pages10
JournalNeurotoxicology and Teratology
Volume28
Issue number1
DOIs
StatePublished - Jan 2006

Fingerprint

Coproporphyrinogen Oxidase
Dental Assistants
Genetic Polymorphisms
Polymorphism
Mercury
Tooth
Gene encoding
Porphyrins
Fingers
Heme
Hand
Exons
Education
Alcohols
Health
Cheek
Biosynthetic Pathways
Occupational Exposure
Vibration
Dentists

Keywords

  • Coproprophyrinogen oxidase
  • Mercury
  • Neurobehavioral toxicity
  • Polymorphism

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience
  • Neuroscience(all)
  • Toxicology

Cite this

The association between a genetic polymorphism of coproporphyrinogen oxidase, dental mercury exposure and neurobehavioral response in humans. / Echeverria, Diana; Woods, James S.; Heyer, Nicholas J.; Rohlman, Diane; Farin, Federico M.; Li, Tingting; Garabedian, Claire E.

In: Neurotoxicology and Teratology, Vol. 28, No. 1, 01.2006, p. 39-48.

Research output: Contribution to journalArticle

Echeverria, Diana ; Woods, James S. ; Heyer, Nicholas J. ; Rohlman, Diane ; Farin, Federico M. ; Li, Tingting ; Garabedian, Claire E. / The association between a genetic polymorphism of coproporphyrinogen oxidase, dental mercury exposure and neurobehavioral response in humans. In: Neurotoxicology and Teratology. 2006 ; Vol. 28, No. 1. pp. 39-48.
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T1 - The association between a genetic polymorphism of coproporphyrinogen oxidase, dental mercury exposure and neurobehavioral response in humans

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N2 - We previously described a polymorphism in exon 4 of the gene encoding the heme biosynthetic pathway enzyme, coproporphyrinogen oxidase (CPOX4), which significantly modifies the effect of mercury exposure on urinary porphyrin excretion in humans. Here, we examined potential consequences of this polymorphism ("CPOX4") on performance within neurobehavioral domains, symptoms, and mood that are known to be affected by elemental mercury (Hg°) exposure in human subjects. A behavioral test battery was administered on the day of urine and buccal cell collections for 194 male dentists (DDs) and 233 female dental assistants (DAs) occupationally exposed to Hg° for an average of 19 and 10 years, respectively. Subjects had no history of health disorders and were employed for a minimum of 5 years in the dental profession. Respective mean urinary mercury (HgU) levels in DDs and DAs were 3.32 (4.87) μg/l and 1.98 (2.29) μg/l. Corresponding indices of chronic occupational Hg° exposure, weighted for historical exposure, were 27.1 (20.6) and 15.2 (12.3). The frequencies of the homogygous common (A/A), heterozygous (A/C), and homozygous polymorphic (C/C) genotypes were 75%, 23% and 2% for DDs and 73%, 25%, and 2% for DAs, respectively. DDs and DAs were evaluated separately. Regression analyses controlled for age, premorbid intelligence, alcohol consumption, and education. Statistically significant associations with HgU (p <0.05) were found for nine measures among DDs (BEES Digit Span Forward and Backward, WMS-R Visual ReproductionN Correct, BEES Symbol DigitRate, BEES Finger TappingDom/Non-dom, and Alternate Partialed, Hand SteadinessFactor1, and BEES Tracking), and eight measures among DAs (BEES Digit SpanForward, BEES Symbol DigitRate, BEES Pattern Discrimination Rate, BEES Trailmaking B, BEES Finger Tapping Dom/Non-dom, and Alternate Partialed, Hand Steadiness Factor1, and Vibration SensitivityHits). CPOX4 status was associated with four measures in DDs (BEES Spatial SpanForward, BEES Pattern MemoryN Correct, BEES Symbol DigitRate, and BEES VigilanceHit) and five measures in DAs (BEES Digit Span Forward, WMS-R Visual ReproductionsN Correct, BEES Symbol DigitRate, BEES Simple and Choice Reaction TimeMove. Both groups experienced an additive effect (no interaction term) for HgU and the CPOX4 polymorphisms on the DigitRate whereas DAs also had additive effects for BEES Digit SpanForward and for Beck's Depression factor 'Worthlessness'. These exploratory findings suggest that the CPOX4 polymorphism may affect susceptibility for specific neurobehavioral functions associated with mercury exposure in human subjects.

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