Purpose: Phenylthiocarbamide (PTC) tasting has been linked to alcohol use. The bitter taste for PTC is mediated by TAS2R38 gene. We have previously shown individuals who taste PTC (genotype TT) as bitter consume less alcohol compared to non-tasters. We studied PTC taste perception and TAS2R38 genotype as possible markers of alcohol risk in both pre and post liver transplant patients.

Methods: 99 pre and post liver transplant patients were studied. Demographic information was gathered in a questionnaire. Taste sensitivity to PTC on a prepared paper strip was assessed as tasteless, mild or bitter. Buccal swabs were taken for genetic analysis with individuals classified as carrying two alleles (TT) bitter taste, one allele (Tt) mild taste or none (tt) no taste. Fisher exact tests were used to determine significant associations between genotype, PTC taste, alcohol use and alcohol related liver disease (ARLD). α was set at 0.05.

Results: Of the patients in the study, 59% were males. Mean age of patients was 58 years (range 20-77 years). 63% had received a transplant. 16% had ARLD. For PTC taste, 37% reported no taste, 40% mild taste, and 22% bitter taste. 17% were TT genotype, 37% Tt, and 23% tt. It was found that TAS2R38 genotype was significantly associated with PTC taste. Neither PTC taste nor genotype was associated with general alcohol use. However, PTC taste did correlate with decreased likelihood for drinking heavily (p=0.02). Bitter tasters were far less likely to consume large quantities of alcohol.

Conclusions: These results support previous findings that the ability to taste PTC is associated with lower alcohol use. This corroborates the association between PTC taste and TAS2R38 genotype. However, we found that while the lack of PTC taste is associated with heavy alcohol use, the TAS2R38 genotype has not been consistent. This may be due to TAS2R38 not associating perfectly with PTC taste. PTC taste is more directly indicative of low alcohol consumption and no taste with high alcohol intake than genotyping. Relapse of alcohol use is a consideration for selecting patients for liver transplantation. A simple, cheap, office-based PTC taste test to identify individuals at high risk for heavy alcohol use and to substantiate those that do not drink may become a helpful parameter for listing ARLD patients. More study on recidivism is warranted.

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