ALLELIC HETEROGENEITY cystic fibrosis(cF) autosomal recessive disorder affecting 1/2500 newborns in populations of European origin phenotype: sticky viscous secretions >obstruction of pancreas and airways> pancreatic insufficiency(treated with enzyme supplements)+ lung infections mapped to chromosome 7 by genetic linkage analysis in 1985 gene identified at molecular level in 1989: encodes a chloride channel protein >600 mutant alleles in the gene have been identified allelic heterogeneity Would such allelic heterogeneity affect the outcome of combining LOD scores from multiple families with affected children No, because all such families would show linkage to the same chromosomal locusALLELIC HETEROGENEITY cystic fibrosis (CF): • autosomal recessive disorder affecting 1/2500 newborns in populations of European origin • phenotype: sticky viscous secretions  obstruction of pancreas and airways  pancreatic insufficiency (treated with enzyme supplements) + lung infections • mapped to chromosome 7 by genetic linkage analysis in 1985 • gene identified at molecular level in 1989: encodes a chloride channel protein allelic heterogeneity Would such allelic heterogeneity affect the outcome of combining LOD scores from multiple families with affected children? No, because all such families would show linkage to the same chromosomal locus. • > 600 mutant alleles in the gene have been identified