A recessive mutation in the TYR gene, which codes for the enzyme tyrosinase, can cause albinism. People with this type of albinism are homozygous recessive. Describe the phenotype of a person with albinism.
A recessive mutation in another gene causes a form of albinism that mainly affects the eyes (ocular albinism). A person with this condition has reduced visual clarity and involuntary eye movements. Fig. 2.1 shows the inheritance pattern of ocular albinism in one family. The pattern shows sex-linked inheritance.
Explain why Fig. 2.1 provides support for sex-linked inheritance of ocular albinism.
Draw a genetic diagram to show why individuals 1 and 2 cannot have a child with ocular albinism. Include: key to symbols parental genotypes gametes offspring genotypes offspring phenotypes
A base deletion mutation may cause ocular albinism. The mutation leads to a non-functional protein. Explain how a base deletion mutation can result in a non-functional protein.
Ocular albinism is a non-progressive disorder and visual clarity stays the same throughout life. A female has a family history of ocular albinism but has no symptoms. A test is available to find out whether she carries the mutant allele. Suggest one reason for taking this test and one reason against taking this test.