9. For some non-Mendelian inheritance patterns, the genotype of an individual is not sufficient to predict the phenotype. For the following traits, what else do you need to know to predict the phenotype? a) Snail coiling direction b) Angelman syndrome due to deleted UBE3A gene Solution The inheritance mechanisms of both snail coiling and Angelman syndrome involve strong maternal influences. Snail coiling direction is governed by the genotype of the oocyte, not of the zygote, so much so that the snail coiling direction can be predicted from the maternal genotype alone. Similarly, Angelman syndrome (due to deletions in ube3A) is governed by the maternal copy of the gene alone. If the copy of the gene derived from the mother is functional, the individuals are healthy. If the maternal copy is defective or deficient, the individual suffers from the Angelman syndrome..

1. 9. For some non-Mendelian inheritance patterns, the genotype of an individual is not sufficient to
predict the phenotype. For the following traits, what else do you need to know to predict the
phenotype?
a) Snail coiling direction
b) Angelman syndrome due to deleted UBE3A gene
Solution
The inheritance mechanisms of both snail coiling and Angelman syndrome involve strong
maternal influences. Snail coiling direction is governed by the genotype of the oocyte, not of the
zygote, so much so that the snail coiling direction can be predicted from the maternal genotype
alone. Similarly, Angelman syndrome (due to deletions in ube3A) is governed by the maternal
copy of the gene alone. If the copy of the gene derived from the mother is functional, the
individuals are healthy. If the maternal copy is defective or deficient, the individual suffers from
the Angelman syndrome.