Question

You are studying the disease called beta-thalassemia, the most prevalent monogenic heritable disease, in which no beta-globin is produced. The absence of beta-globin causes anemia, aka thalassemia. Research showed that the beta-globin gene’s coding region in a subset of the individuals with this disease appeared normal, but the mRNA is slightly longer than normal (by 19 nucleotide). You sequenced the beta -globin gene of the affected individuals and found a single base change within the gene’s first intron. Present a hypothesis to explain the absence of beta -globin in these subjects.

Answer 1

The beta-globin gene of the affected individual has the mutation at the first intron and that produces longer mRNA than the normal individual so, it clearly indicates the mutation is in the splice site of the gene which prevents the splicing of the first intron. That is the reason, processed mRNA in the affected individual is longer than normal individuals. Mutation at splice site of the gene will prevent the formation of mature mRNA therefore it will not expressed in the affected individual.