Problem:
Analysis of the DNA of the Phenylalanine hydroxylase (PAH) gene in a patient with phenylketonuria revealed a mutation in the protein coding region whose predicted effect would be to replace the amino acid aspartic acid, with histidine.
Nevertheless, no mutant protein could be found in the patient's cells.
Required:
Question: How this could be as mutation is in the protein coding region? Explain thoroughly.