Multiple Chemical Sensitivity and the SLC Gene Superfamily: A Case-Control Study

Multiple chemical sensitivity (MCS) is a disease of unknown etiology with multiple symptoms. Triggered by exposure to environmental chemicals, it results in multiorgan effects. Studies on MCS use different approaches, ranging from searches for environmental triggers to susceptibility genes. Genetic research deals with genes for chemical detoxification, oxidative stress, inflammation, and neurodegeneration, as well as immune function and mast cell activation, with uneven results. The sensory hyperexcitability symptom has not been studied yet but has recently been linked to a member of the SLC gene superfamily. To explore its role in MCS disease, a complete-exome analysis was performed in a small number of subjects. Low-frequency genetic variants were analyzed for each individual, and their homozygous or heterozygous presence was determined in four groups of genes related either to the SLC superfamily members or to previous studies in MCS. We found homozygous rare variants in affected individuals only for the SLC gene superfamily, where each patient had at least one. Variants in heterozygosis and certain SNPs also point to SLC genes related to neurotransmitter synthesis, release, and clearance, as well as to the level of cellular excitability, as potentially underlying the differences.