A genetic variant that causes smokers to smoke heavily is linked to obesity, researchers warned today.
The findings may help explain why some people say smoking helps them keep slim – as, according to the researchers, this is what happens to people with this gene variant.
Research led by the University of Bristol, England, looked at a variant in the CHRNA5-A3-B4 gene cluster, which is known to increase the amount smokers smoke.
Now, Professor Marcus Munafo from Bristol’s School of Experimental Psychology and colleagues say in PLOS Genetics that the variant is associated with lower body mass index in current smokers – but in people who have never smoked, it is linked to a greater body weight.
He admitted that the reason for the association in people who have never smoked is not yet understood, although it is known that this genetic variant alters response to nicotine.
“One explanation for the association with body mass index in never smokers is that the nicotinic acetylcholine receptors this particular gene codes for may play a more general role in our response to reward – which could include natural rewards such as food,” he said.
Prof Munafo said the study highlights the potential importance of accounting for environmental factors in genetic studies.
The link between this particular genetic variant and BMI was discovered when the study population was divided into never, former and current smokers.
Taylor A et al. Stratification by Smoking Status Reveals an Association of CHRNA5-A3-B4 Genotype with Body Mass Index in Never Smokers. PLOS Genetics. Volume 10. Issue 12. 4 December 2014. [abstract]
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