Below left is a pedigree of a family with a history of Best

Last updated: 8/24/2023

Below left is a pedigree of a family with a history of Best disease vitelliform macular dystrophy an autosomal recessive condition As part of a study aiming to identify the gene responsible for this condition members of an affected family were genotyped for alleles of a SNP locus closely linked to the Best disease gene using ASO technology with results shown below right In the diagram Illustrating ASO results 1 and 2 refer to ASO probes specific for two different alleles of the SNP locus with filled circles showing where hybridization signal was observed and open circles showing where signal was not observed Numbers across the top of the ASO results diagram refer to individuals in the pedigree In the pedigree the numbers below each individual symbol indicate individual numbers in each generation not SNP alleles 1 11 III Part 1 1 2 2 0 0 O 25 50 3 ASO 1 ASO 2 O SNP allele 1 O There is not enough information to answer this question O SNP allele 2 1 1 If there is no recombination between the SNP and the Best disease gene which SNP allele is on the same chromosome as the disease allele 1 2 11 1 11 2 11 3 Part 2 What is the probability that Individual III 1 the child in the third generation will have Best disease To answer this question consider the genotype of the child s father and continue assuming no recombination between the SNP and the disease gene