Mutant sites in the PKU gene

Many mutations of the human phenylalanine hydroxylase gene that cause enzyme malfunction are known. The number of mutations in the exons, or protein-encoding regions (black), are listed above the gene. The number of mutations in the intron regions (green, numbered 1 through 13) that alter splicing are listed below the gene.

[Data from C. R. Server, Ann. Rev. Genet. 28, 1994, 141–165]