Human histamine N-methyltransferase pharmacogenetics: Common genetic polymorphisms that alter activity
Mayo Clinic - Rochester, Рочестер, Minnesota, United StatesMolecular Pharmacology (Impact Factor: 4.13). 05/1998; 53(4):708-17.
Histamine N-methyltransferase (HNMT) catalyzes a major pathway in histamine metabolism. Levels of HNMT activity in humans are regulated by inheritance. We set out to study the molecular basis for this genetic regulation. Northern blot analysis showed that HNMT is highly expressed in the kidney, so we determined levels of enzyme activity and thermal stability in 127 human renal biopsy samples. DNA was isolated from 12 kidney samples with widely different HNMT phenotypes, and exons of the HNMT gene were amplified with the polymerase chain reaction. In these 12 samples, we observed a C314T transition that resulted in a Thr105Ile change in encoded amino acid, as well as an A939G transition within the 3'-untranslated region. All remaining renal biopsy samples then were genotyped for these two variant sequences. Frequencies of the alleles encoding Thr105 and Ile105 in the 114 samples studied were 0.90 and 0.10, respectively, whereas frequencies for the nucleotide A939 and G alleles were 0.79 and 0.21, respectively. Kidney samples with the allele encoding Ile105 had significantly lower levels of HNMT activity and thermal stability than did those with the allele that encoded Thr105. These observations were confirmed by transient expression in COS-1 cells of constructs that contained all four alleles for these two polymorphisms. COS-1 cells transfected with the Ile105 allele had significantly lower HNMT activity and immunoreactive HNMT protein than did those transfected with the Thr105 allele. These observations will make it possible to test the hypothesis that genetic polymorphisms for HNMT may play a role in the pathophysiology of human disease.
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- "Polymorphisms of genes that regulate CNS dopamine levels, such as the dopamine transporter gene (DAT1), are associated with childhood ADHD (Gizer, Ficks, & Waldman, 2009). Polymorphisms in the histamine degradation gene (HNMT) result in impaired clearance of histamine which is released following a challenge with food additives (Murdoch, Lessof, Pollock & Young, 1987;Preuss et al., 1998). In a double blind, randomized placebo controlled study, children with ADHD with specific HNMT or DAT1 polymorphisms experienced worsening clinical symptoms when challenged with food additives compared to children lacking these polymorphisms. "
ABSTRACT: Background: Complementary and alternative medicine (CAM) in psychiatry or integrative psychiatry covers a wide range of biological, psychological and mind-body treatments that enhance standard medical practices and patient outcomes. While CAM approaches are popular among patients, health professionals have received limited education in these interventions and they are often unaware of their patients’ use of CAM treatments. Method: This overview highlights evidence-based CAM treatments for attention deficit hyperactivity disorder (ADHD) including dietary interventions, phytomedicines, mind-body practices and neurofeedback. Results: While conventional treatments are the mainstays for ADHD, there are a large number of available treatments that can be used to enhance treatment response. Conclusion: With improved education and further scientific and clinical research, validated integrative treatments will provide more effective, lower risk and lower cost care for patients with ADHD.
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- "The 939A>G polymorphism is a common SNP in HNMT.15 A study in a European population reported no association between 939A>G and food allergy,20 and a study in an Indian population found no association of this polymorphism with asthma.18 "
ABSTRACT: Purpose Histamine N-methyltransferase (HNMT) catalyzes one of two major histamine metabolic pathways. Histamine is a mediator of pruritus in atopic dermatitis (AD). The aim of this study was to evaluate the association between HNMT polymorphisms and AD in children. Methods We genotyped 763 Korean children for allelic determinants at four polymorphic sites in the HNMT gene: -465T>C, -413C>T, 314C>T, and 939A>G. Genotyping was performed using a TaqMan fluorogenic 5' nuclease assay. The functional effect of the 939A>G polymorphism was analyzed. Results Of the 763 children, 520 had eczema and 542 had atopy. Distributions of the genotype and allele frequencies of the HNMT 314C>T polymorphism were significantly associated with non-atopic eczema (P=0.004), and those of HNMT 939A>G were significantly associated with eczema in the atopy groups (P=0.048). Frequency distributions of HNMT -465T>C and -413C>T were not associated with eczema. Subjects who were AA homozygous or AG heterozygous for 939A>G showed significantly higher immunoglobulin E levels than subjects who were GG homozygous (P=0.009). In U937 cells, the variant genotype reporter construct had significantly higher mRNA stability (P<0.001) and HNMT enzyme activity (P<0.001) than the common genotype. Conclusions Polymorphisms in HNMT appear to confer susceptibility to AD in Korean children.
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- "The HNMT gene is located in chromosome 2q22.1. One common nonsynonymous SNP causing Thr105Ile amino-acid substitution (rs1801105) is associated with reduced thermal stability and decreased HNMT activity , . No other nonsynonymous SNPs with frequencies over 0.01 have been described for this gene . "
ABSTRACT: Non-steroidal anti-inflammatory drugs (NSAIDs) are the drugs most frequently involved in hypersensitivity drug reactions. Histamine is released in the allergic response to NSAIDs and is responsible for some of the clinical symptoms. The aim of this study is to analyze clinical association of functional polymorphisms in the genes coding for enzymes involved in histamine homeostasis with hypersensitivity response to NSAIDs. We studied a cohort of 442 unrelated Caucasian patients with hypersensitivity to NSAIDs. Patients who experienced three or more episodes with two or more different NSAIDs were included. If this requirement was not met diagnosis was established by challenge. A total of 414 healthy unrelated controls ethnically matched with patients and from the same geographic area were recruited. Analyses of the SNPs rs17740607, rs2073440, rs1801105, rs2052129, rs10156191, rs1049742 and rs1049793 in the HDC, HNMT and DAO genes were carried out by means of TaqMan assays. The detrimental DAO 16 Met allele (rs10156191), which causes decreased metabolic capacity, is overrepresented among patients with crossed-hypersensitivity to NSAIDs with an OR = 1.7 (95% CI = 1.3–2.1; Pc = 0.0003) with a gene-dose effect (P = 0.0001). The association was replicated in two populations from different geographic areas (Pc = 0.008 and Pc = 0.004, respectively). Conclusions and implications The DAO polymorphism rs10156191 which causes impaired metabolism of circulating histamine is associated with the clinical response in crossed-hypersensitivity to NSAIDs and could be used as a biomarker of response.
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