Reference no: EM133669378

Question: Explain "Screening for the single-nucleotide deletion in exon 8. The single-nucleotide deletion (P2) within exon 8 causes a frameshift within the codon for E326 and introduces a novel carboxyl-terminal coding sequence (S-L-P-P-L-F-A) followed by a stop codon (Figure ?(Figure3a).3a). Although this results in the loss of a BbsI site, the development of a screening assay was complicated because this occurs in close proximity to a relatively common SNP (P3), which introduces an additional consensus site for N-glycosylation (Figure ?(Figure3a)3a) due to a D327N substitution (20). Nevertheless, discrimination between P3 and P2 could be accomplished by separate digestions of PCR products spanning this region with BbsI and HinfI (Figure ?(Figure3b).3b). In subjects with either the P2 or P3 sequence variations, a BbsI site in the consensus SHBG sequence is disrupted (Figure ?(Figure3b).3b). However, alleles containing P3 also lack the HinfI site present in the consensus sequence, which is preserved in the allele containing