We have developed and applied to LDLR, a mutation scanning approach suitable for whole population screening for unknown mutations. Applications include definition of population-based 'lefelence ranges' for rat'er sequence vat'iation; characterisation of 'paucimorphisms' (arbitrarily defined here as variants of rater allele fi'equency, 0.05%A (n=2). Around exon 8 we identified a paucimorphism (n=35) at splice site 1061-8 T>C (known to be in complete linkage disequilibrium with T705I); and unknown splice 1186+11 G>A (n=l) and D335N G>A (n=l). D335N and a significant fi'action of T705I subjects displayed cholesterol values above the 95th centile. Thus both severe, moderate and silent vat'iants were identified, at the population level.