(Choice B) A complete failure of gene expression would lead to a failure to produce the protein, which can be detected by Western blotting. However, the question is asking how to determine if the gene is being transcribed (genes may be transcribed but not properly expressed if there is a problem with protein translation). As transcription refers 10 the production of mRNA from a DNA template, a test that detects specific mRNA sequences (Northern blot) would be most appropriate.
(Choices C and D) This patient’s mutation in a non-coding DNA sequence (likely affecting a promoter or enhancer region) is resulting in decreased gene expression. A Southern or Southwestern blot could potentially be used to
detect the mutated DNA sequence and assess for transcription factor binding. However, the degree of transcription of the affected gene is better assessed through direct detection of its associated mRNA.
(Choice E) ELISA (enzyme-linked immunosorbent assay) is a test commonly employed to measure the amount of a protein in body fluids. It can be quantitative, for example, to measure plasma insulin levels.