What have we 'Ear'?

An AOP publication in Nature Genetics claims to have identified a gene involved in the secretion of wet earwax (Yoshiura et al). Quite why they chose to investigate this trait is beyond my understanding (after all I feel that auto-immune and cardio-vascular diseases and cancers have a far larger impact on human health world-wide than the need for the occasional ear syringe), particularly given that it is mendelian and not polygenic in nature, despite the contentious nature of the association with breast-cancer (which is likely to only be pure co-incedence).

The claim that this is "...the first example of DNA polymorphism determining a visible genetic trait" is I feel somewhat grandiose and misled as there are innumerable polmorphims which have a direct effect on the phenotype of individuals who carry them, for example the ΔF508 mutation in Cystic Fibrosis, or the Huntington's Disease gene.

More interstingly the current issue of Nature Genetics has an article on a sex-xpecific QTL (Quantitative-Trait Locus). In this article they review 17 quantitative traits (including systolic and diastolic blood pressure, triglycerides, serontin levels, LDL and HDL levels) in the Hutterite's to see if there are any sex-specific effects. They found that 11 of these showed differences between the sexes at a significance level of p < 0.05 (although really they should have applied a Bonferroni correction and set the significance level to 0.0029 at a bare minimum assuming all the traits were independent). Heritability differed between sexes in some cases as well.

This obviously has important implications when analysing genetic data for QTL's and sex should therefore always be included in the early stages of the analysis to determine whether it has a significant effect.

Links

Complex Trait Mapping in the Hutterites