Chapter 13, Problem 17P

A hereditary disease is inherited as an autosomalrecessive trait. The wild $\text{-}$ type allele of the disease geneproduces a mature mRNA that is $\text{1250}$ nucleotides (nt) long. Molecular analysis shows that the mature mRNAconsists of four exons that measure $400$ nt(exon $\text{1}$), $\text{320}$ nt(exon $\text{2}$), $\text{230}$ nt(exon $\text{3}$), and $\text{300}$ nt(exon $\text{4}$).A mother and father with two healthy children and twochildren with the disease have northern blot analysisperformed in a medical genetics laboratory. The results of the northern blot for each family member are shown here.

a. Identify the genotype of each family member, using the sizes of mRNAs to indicate each allele. (For example, a person who is homozygous wild type is indicated as $\text{“1250/1250}\text{.”}$)

b. Based on your analysis, what is the most likely molecular abnormality causing the disease allele?