Based on this ASO test, which patient(s) definitely have CF? Patient 1,2,3 or 4?Based on this ASO test, which patient(s) do NOT have CF? Patient 1,2,3 or 4? There are over 600 different mutations in the CFTR gene that can lead to Cystic Fibrosis (autosomal recessive disorder)Exons14a1 23 4 5 6a6b 7 8 9 10 1112 13 ¹4 14 15 1617a17b 1819202122 23 24||| ||||Mutations00ASO AWWOONOASO B00●70% of people with Cystic Fibrosis have a 3 base pair deletion in exon 10 (redbox.)DASO A hybridizes to the wild type exon 10ASO B hybridizes exon 10 containing the 3 base pair deletion➖➖➖➖➖100●1 22 3 4

Cystic fibrosis is a genetic disease that can be fatal. It causes the build-up of abnormally thick mucus which proves to be harmful to the organs. Mucus is secreted normally in the body as a thin slippery substance that lines and lubricates body systems. People with cystic fibrosis secrete mucus that is excessively thick and sticky thereby clogging the airways and gastrointestinal linings. This results in respiratory and gastrointestinal damage.ASO is the abbreviated form of the allele-specific oligonucleotide. It is an oligonucleotide probe designed for a specific sequence. In the given question, ASO A is designed for the wild-type DNA while ASO B is designed for the mutant DNA (3 base pairs deletion). When the ASO is hybridized with the given DNA successfully, a spot is created in the autoradiogram. In the case of ASO A, a spot is created only when the DNA of the patient matches that of the wild-type DNA. In the case of ASO B, a spot is created if the patient carries a mutation in one allele or both alleles. The spot indicates a heterozygous carrier or a homozygous mutant. The patient with Cystic Fibrosis has a three-base pair deletion and hence would not form any spot when hybridized with ASO A. Hence, patient 4 definitely has cystic fibrosis. Cystic fibrosis is a recessive disease, that is, both the mutant alleles must be present to show the disease. The patients with a spot in ASO A are not having cystic fibrosis as it contains at least one normal allele. Hence, patients 1, 2, and 3 do not have cystic fibrosis. The presence of no spot in ASO B indicates that the patient is homozygous normal. The rest of them are either heterozygous or homozygous mutants. Based on this, Patient 1: Homozygous normal, no disease. Patient 2: Heterozygous, no disease. Patient 3: Heterozygous, no disease Patient 4: Homozygous mutant, disease present. Hence, patient 4 definitely has cystic fibrosis. Hence, patients 1, 2, and 3 do not have cystic fibrosis.