Final answer:
Humans heterozygous for a Pax-6 mutation typically develop aniridia, a condition characterized by the absence of the iris in the eye.
Step-by-step explanation:
Humans heterozygous for a Pax-6 mutation develop aniridia. Pax-6 is a gene important in eye development, and when a mutation occurs, it can lead to this condition, characterized by the absence of the iris in the eye. The other options provided, such as albinism, cataracts, and glaucoma are associated with other genetic mutations or health conditions.