Retinitis pigmentosa, a group of related eye disorders that cause progressive vision loss, is due to an autosomal dominant allele. Tay-Sachs disease, on the other hand, is due to a defective gene with incomplete dominance. A mutation in the recessive HEXA gene prevents the synthesis of the lysosome enzyme beta-hexosaminidase A. This mutation prevents the breakdown of GM2 ganglioside, thus increasing to a toxic level that damages neurons. Luisa is a carrier of the allele for Tay-Sachs but has no sign of any eye disorder in her family. She married Gerard whose mother was afflicted with retinitis pigmentosa, unlike his father. Neither of his parents has any history of Tay-Sachs disease.
Retinitis pigmentosa, a group of related eye disorders that cause progressive vision loss, is due to an autosomal dominant allele. Tay-Sachs disease, on the other hand, is due to a defective gene with incomplete dominance. A mutation in the recessive HEXA gene prevents the synthesis of the lysosome enzyme beta-hexosaminidase A. This mutation prevents the breakdown of GM2 ganglioside, thus increasing to a toxic level that damages neurons.
Luisa is a carrier of the allele for Tay-Sachs but has no sign of any eye disorder in her family. She married Gerard whose mother was afflicted with retinitis pigmentosa, unlike his father. Neither of his parents has any history of Tay-Sachs disease.
- What are the genotypes of Luisa and Gerard?
Luisa:______________________________Gerard:_____________________________
2. If they plan to have five children, what is the probability that:
- all their children will be normal? _________________________________
- they will have a daughter with retinitis pigmentosa? _______________________
- they will have a son inflicted with both conditions? ________________
- at least 2 will be normal? (show COMPLETE solutions for this question)
Step by step
Solved in 4 steps with 4 images
