Genetic Variation in the Vesicular Monoamine Transporter: Preliminary Associations With Cognitive Outcomes After Severe Traumatic Brain Injury.
Steven M Markos, Michelle D Failla, Anne C Ritter and 6 others
PMID 26828714WHAT IT FOUND
A VMAT2 gene variant was linked to worse cognitive performance after severe TBI.
The link was not seen at the later follow-up. This is an association in a small group, not proof that the variant causes impairment.
Key findings
01The rs363226 genotype was associated with 6-month cognitive composite scores, and the GG group had lower adjusted scores than the CG and CC groups.
02No statistically significant association was found between VMAT2 genotypes and 12-month cognitive composite scores.
03When cognitive composite T-scores were below 40, functional cognition deficits became more pronounced for the GG genotype than for the CG and CC genotypes.
STILL TO COME
How it was doneWhat they foundWhat it means for OTsWhat it means for SLPs
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What it does not show
The sample is small for a genetic association study, and the authors state that larger samples are needed for validation. The analysis was limited to White individuals, so the results may not apply to other racial groups. The G-homozygote group was very small, with only 11 of 95 participants. The variant was associated at 6 months but not at 12 months, so the time course is uncertain. The study is associative. It does not show that the VMAT2 variant causes cognitive impairment. The functional consequences of rs363226 are unknown. Functional cognition was rated by self or caregiver report, which can be variable when cognitive deficits or depression are present.
Declared interests
The authors declared no conflicts of interest. The publication types indicate NIH extramural and U.S. government non-P.H.S. research support.
The easy way to misread this
Do not conclude that this gene variant causes cognitive impairment or that genotype should guide treatment. The study reports an association in a small sample, the variant has unknown function, and the association was not found at the later follow-up.