Question

. Compare/ contrast (3 pts each) a. Give one characteristic that is the same between X-inactivation and genomic imprinting, then give one characteristic that is different between them. b. Give one characteristic that is the same between autosomal recessive and X-linked recessive inheritance, then give one characteristic that is different between them. c. Give one characteristic that is the same between hemophilia and congenital hypertrichosis, then give one characteristic that is different between them.

Answer 1

a) X-inactivation refers to silencing of one of the X-chromosome in female mammals. Whereas genome imprinting is an epigenetic phenomenon that causes genes to be expressed in a parent of origin specific form.

Similarity: Both are epigenitic mechanisms that involves DNA methylation and histone methylation that leads to silencing of X-chromosome genes or imprinted genes.

Difference: Imprinting is very specific to the allele that is inherited from a specific parent(father or mother) whereas X-inactivation is random inactivation of X-chromosome of either maternally or paternally derived X-chromosome.

b) Similarity: Since both are recessive traits hence two copies of a diseased allele is required to express the phenotype(except for males as they are hemizygous for X-chromosome).

Difference: Autosomal recessive traits equally affects both males and females, whereas X-linked tarits mostly affects male individuals(as they are hemizygous for X-chromosome) and females are generally carriers of the disease.

c) Similarity: Both hemophilia and Congenital hypertrichosis are inheritable genetic disorders caused by genetic mutations.

Difference: Hemophilia is a X-linked recessive trait characterized by inability to make blood clots whereas Congenital hypertrichosis has a dominant pattern of inheritance(X-linked dominant trait) and is characterized by excessive hair growth over the body.