Techniques such as Mendelian Randomisation may help to tease apart determine the extent to which the pathways are shared versus linear (for example, genes to cognitive function, to BMI).44 The GWAS hits that are significant for both traits are found in genes linked to insulin-related processes (AKAP6), lipid transportation and Alzheimer's disease (TOMM40), retinal arterioral calibre (TMEM161B) and height (TNRC6B). This evidence concerns the gene TNRC6B and early-onset autosomal dominant Alzheimer disease.