Changes in chromosome number may be caused by nondisjunction during sperm or egg formation. Let's supposed a couple, neither of whom have X-linked colorblindness (a recessive disorder) themselves, have a daughter with Turner Syndrome and with X-linked color blindness. The daughter's color blindness is not due to a new mutation. Draw a Punnett square to explain the daughter's genotype and list the parent's genotypes below (write as X-X- and X-Y with the appropriate alleles next to their chromosomes; be sure to indicate dominant and recessive alleles appropriately).