Routine metabolic screening of a newborn female revealed elevated levels of phenylalanine in the plasma

Routine metabolic screening of a newborn female revealed elevated levels of phenylalanine in the plasma. The child was placed on a special diet that restricts phenylalanine intake to prevent mental retardation and other neurodegenerative effects that result from phenylalanine toxicity. DNA sequencing of the newborn revealed pathogenic variants in both copies of the gene that encodes phenylalanine hydroxylase. In both cases, the variant changed an alanine codon to a stop codon. Each parent has one ofthe pathogenic variants, yet their plasma phenylamine levels were normal. A. (1 point) What is the name for this type of pathogenic variant (mutation)? B. (1 point) What is this pattern of inheritance? C. (1 point) Why are the parents not affected by the pathogenic variant?