Multiple chemical sensitivity (MCS) is a complex clinical entity that includes a large number of non-specific symptoms, associated in a univocal manner in each patient and triggered by exposure to various chemicals at low concentrations, well below those known to cause toxic effects.


[Barnig and de Blay; 2013 (in French)]

Multiple Chemical Sensitivity (MCS) is a chronic condition characterized by recurrent, non-specific symptoms in response to chemically unrelated exposures in non-toxic concentrations


[Tran et al;2013]
The sensitization state of CS seems to be initiated by a significant toxic exposure, occurring as a 1-time event, or on surpassing a threshold of toxicity after toxicant accrual from repeated lower-level exposures. Once sensitized through a toxicant-induced loss of tolerance, individuals exposed to inciting triggers such as minute amounts of diverse everyday chemicals may experience various clinical and immune sequelae, sometimes involving lymphocyte, antibody, or cytokine responses.


[Genuis SJ.; 2013]
Multiple chemical sensitivity (MCS) is a chronic condition, which belongs to the group of medically unexplained syndromes. Patients (men as well as women) complain of many subjective symptoms such as nose and mouth irritation, sore throat, dyspnea, tiredness, dizziness, headache and concentration difficulties. Patient typically report at least four or five symptoms occurring when they are exposed to particular substances, at a very low concentration that usually does not cause symptoms or harm in normal individuals. The common feature of products that appear to be responsible (either occupational or domestic) is that they have a strong smell and include: solvent, paint, glue, tar, oil, pesticides, perfume, cosmetics and spray products. MCS is nowadays considered to be one aspect of idiopathic environmental intolerance (IEI) whose other main aspect is hypersensitivity to electromagnetic fields.


[Dupas and Dagorne; 2013(in French)]
ただし、[Hillert et al; 2013]によるPET測定では、MCS患者は健常者よりもむしろ臭いに反応していない。

[Fujimori S, Hiura M, Yi CX, Xi L, Katoh T.: "Factors in genetic susceptibility in a chemical sensitive population using QEESI.", Environ Health Prev Med. 2012 Sep;17(5):357-63. doi: 10.1007/s12199-011-0260-8. Epub 2011 Dec 29.]

OBJECTIVES: Inherited impairment of xenobiotic metabolism is a postulated mechanism underlying environmentally associated pathogeneses such as multiple chemical sensitivity (MCS). Using the Quick Environmental Exposure and Sensitivity Inventory (QEESI), we defined people who have a strong response to chemical substances as "chemical sensitive populations (CSP)." The aim of this study is to evaluate the condition of subjects sensitive to chemicals and to analyze their genotypes in order to identify susceptibility factors in CSPs in Japanese populations.
METHODS: A total of 1,084 employees of Japanese companies were surveyed using the QEESI, history of MCS, and sick house syndrome. The common genotypes of the participants were analyzed for glutathione S-transferase (GST) M1, GSTT1, aldehyde dehydrogenase2 (ALDH2), and paraoxonase1 (PON1) in order to identify factors in the susceptibility to sensitivity to chemicals.
RESULTS: Four subjects had history of diagnosis of MCS; no subjects had diagnosis of sick house syndrome. The subjects were divided into four levels according to scores of 0, 1-19, 20-39, and 40 or more on three of the QEESI subscales. In addition, we used the MCS criteria by Hojo to differentiate between cases (CSP) and controls. No significant differences in the allelic distribution of genetic polymorphisms in the GSTM1, GSTT1, ALDH2 or PON1 genes were found among the four levels of each subscale, or between cases and controls.
CONCLUSIONS: Our findings suggest that the common genotypes of GSTM1, GSTT1, ALDH2, and PON1 are of little importance to CSP in a Japanese population.

目的: 異物代謝の遺伝的損傷は、MCSのような環境に関連した病態の根底にあるメカニズムと仮定されている。QEESI(クィック環境曝露過敏インベントリ)により、我々は化学物質に強く反応する人々を「化学過敏集団(CSP)」と定義した。本研究の目的は、患者音化学物質への過敏の条件を評価し、遺伝子型を分析して、日本人集団におけるCSPの感受性因子を同定することである。
結果:被験者のうち4名が、MCSの診断履歴があった。またシックハウス症候群の診断履歴はなかった。QEESIサブスケールのうち3つに基づいて、被験者を0, 1-19, 20-39, 40以上の4グループに分割した。さらに、HojoのMCS規準にしたがって、症例(CSP)と健常者(対照群)を識別した。GSTM1とGSTT1とALDH2とPON1遺伝子について、遺伝子多型の対立遺伝子分布に有意な差は、4レベルの間にも、症例(CSP)と健常者(対照群)の間にも見られなかった。

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