phenylketonuria (pku) a human disease characterized by mental retardation results from the
Phenylketonuria Phenylketonuria is a genetic disorder inherited from a person's parents.[1] It is due to mutations in the PAH gene, which results in low levels of the enzyme phenylalanine hydroxylase.[1] This results in the buildup of dietary phenylalanine to potentially toxic levels.[1] It is autosomal recessive, meaning that both copies of the gene must be mutated for the condition to develop.[1] There are two main types, classic PKU and variant PKU, depending on if any enzyme function remains.[1] Those with one copy of a mutated gene typically do not have symptoms.[1] Many countries have newborn screening programs for the disease.[3]
Dwarfism Dwarfism, also known as short stature, occurs when an organism is extremely small.[1] In humans, it is sometimes defined as an adult height of less than 4 feet 10 inches (58 in; 147 cm), regardless of sex, although some individuals with dwarfism are slightly taller.[2][3] Disproportionate dwarfism is characterized by either short limbs or a short torso. In cases of proportionate dwarfism, both the limbs and torso are unusually small. Normal intelligence and lifespan are usual.[4]