A disease called phenylketonuria causes mental retardation, reduces skin pigmentation, and also affects the coloration of urine. What kind of effect is exhibited by the gene responsible for this disease?

A.) pliotropic
B.) Epistatic
C.) Polygenic

Question

A disease called phenylketonuria causes mental retardation, reduces skin pigmentation, and also affects the coloration of urine. What kind of effect is exhibited by the gene responsible for this disease?

A.) pliotropic
B.) Epistatic
C.) Polygenic

anonymous · Answer

"Pleiotropy" is where one single gene controls more than one phenotype. 

You probably already know what a "gene" is. 

And a PHENOTYPE can be another word for APPEARANCE. 
(It's more like a PHYSICAL MANIFESTATION.) 

~~~~~~~~~

Phenylketonuria is a genetic disorder, 
where one defective (bad) gene causes a person to have....
1. Mental Retardation
2. Light skin
3. Strange urine color 


Do you see how more than one PHENOTYPE is affected, by phenylketonuria? 

That's what we call "pliotropy."