A 2-month-old, breastfed baby that was normal at bih begins to develop GI problems and cirrhosis of the liver. Molecular analysis indicates a normal amount of galactose-1-phosphate uridyl transferase (GALT) mRNA, but no observable enzyme activity. Which of the following would be the best possible explanation for this?
Nonsense mutation
Gene deletion
Nonsense mutation
Premature transcription termination sequence in the DNA
Promoter mutation