A concrete implication of ncRNA is that we need to look beyond the 2% of DNA that codes for amino acid sequences. We need to look at the entire genome because we now know how little we know about what genes are, how they work and where to find them. ncRNA may explain in part why progress has been slow in identifying linkages and associations with common disorders and complex dimensions (see below). When linkages with DNA markers are found, the next step is to look for the coding DNA nearby that could explain the linkage. A classic example is the first replicable linkage found with a common disorder, which was reading disability (Cardon, Smith, Fulker, Kimberling, Pennington et al., 1994). Ten years and many coding regions later, the culprit gene has still not been identified even though some suspects remain in the line-up (Galaburda et al., 2006; Paracchini, Scerri & Monaco, 2007). Turning to association studies, they have focused on ‘candidate’ genes using DNA markers in coding regions, especially ‘functional’ DNA markers that code for amino acid sequence differences.
