Question

Aabbcc 1 Norr A.D.A. I . Aabbccc AaBbc Aabbcc Ad 11 No Spac... Heading 1 Heading 2 T E . Paragraph Styles 1. If a child has PKU, what is its genotype? aa What are the genotypes of its parents (use A for the dominant allele and a for the recessive allele) Aa 2. Is it possible to count the number of PKU carriers in a population? Why or why not? 3. If 50 of the 500,000 people in Atlanta have PKU, how many people are carriers? 4. In Atlanta, if a woman with PKU marries a man without symptoms of PKU, what is the chance that they will have a child with PKU? 5. If two people without symptoms in Atlanta have a child, what is the chance that the child will have PKU? population Growth

Answer 1

1. PKU is an autosomal recessive condition.People that have PKU have two recessive genes for the disorder. In scientific terms they are homozygous recessive for the PKU trait. The recessive gene which characterizes PKU is inherited from both parents. For a person with PKU, their genotype is "aa", two recessive genes, and their phenotype is PKU. Additionally, heterozygous parent of a PKU individual has a genotype, or genetic makeup, of "Aa", or one dominant gene and one recessive. However, their phenotype, or outwardly displayed characteristic for the trait, is of a normal non-PKU individual.

2. Practicallly with the exact number it is immpossible to count the number of PKU carriers in a population as it a autosomal recessive disorder. So the person or parent with a hetrozygous gene will not show such symptoms and imposiisble to know whether the person has PKU or not. However, certain test are done after 2 or 3 days of birth which help you to diagonise whether the person is suffering from PKU or not.

3. Phenylketonuria (PKU) is an autosomal recessive metabolic disorder that results in mental retardation if untreated during the newborn period. In the Atlanta, 50 out of 50,000 babies is born with PKU. Given this incidence, what percent of the population are heterozygous carriers of the recessive PKU allele is:

q2= 50/50000
q =√ 50/50,000=1/10√10
p = 1 (does not change from "1" in most equations)
2pq = 2 (1) (1/10√​​​​​​​10) = 0.031

Given the above calculations, individuals in the general population are carriers of PKU.

4. In this situation there are two cases:

a) When a woman with PKU marries a man not showing PKU symptoms and may be he a carrier of PKU so unable to show symptoms so there are chances that PKU being a recessive autosomal disorder can have both recessive gene from father carrying PKU and mother as well then child will be born will PKU. Her husband's chance to be a carrier is the population risk of 1/50. The risk for the fetus to inherit the mutation from each parent is 25%.

b) When a woman marriers with a non PKU person then there are no chances child could have PKU.

5. When two persons without symptoms of PKU have a child may be they are carriers of PKU. SO the chances of child getting PKU from each carrier parent is 25%