Pleiotropy

Definition The ability of a gene to affect more than one characteristic. A Several characteristics are affected by the single gene B C

Sickle cell disease The gene Hb codes for production of haemoglobin. Hbs is a mutation. Mutant haemoglobin results in: Brain damage Heart and blood vessel damage Spleen enlargement then atrophy Kidney damage leading to blood in urine

PKU (phenylketonuria) The PKU gene codes for the enzyme phenylalanine hydroxylase. This enzyme converts the phenylalanine to tyrosine. Both are amino acids. Mutations to the gene result in: Mental retardation Reduced hair and skin pigmentation Damage to body parts from toxic levels of phenylalanine PKU is totally benign if a diet free from phenylalanine is maintained.

Fruit fly and vestigial wing The vestigial gene plays a critical role in wing development. vv will develop short wings The affects are: Cannot fly Number of egg strings in a fly's ovaries changes Position of bristles on a fly's scutellum alters, Length of a fly's life decreases

Pigmentation and deafness in cats About 40% of cats with white fur and blue eyes are deaf The gene affects pigmentation as well as ability to hear Pigmentation may play a role in maintaining fluid in ear canals