# What Is the Probability of Their Child Having Sickle Cell Anemia?

• User Name
In summary, the frequency of sickle cell anemia among black Americans is about .0025. When two black Americans marry, the probability that both will be heterozygotes is .25. If both are heterozygotes, the probability that one of their children will have sickle cell anemia is also .25. However, it is important to note that this question is looking at an individual cross, rather than population genetics, so the original frequency of .0025 may not apply.
User Name
Among black Americans, the frequency of sickle cell anemia is about .0025. What is the frequency of heterozygotes? When one black American marries another, what is the probability that both will be heterozygotes? If both are heterozygotes, what is the probability that one of their children will have sickle cell anemia?

I've already solved the first two questions, and now I'm just focusing on the last question. My question is, would the probability of one of their children having sickle cell anemia be the original .0025 that was given to me? Or would it be .25 (the probability of two recessive alleles when you cross two heterozygotes)?

Thanks, in advance. =]

For the last question, you're switching from population genetics to an individual cross. I suspect that's the reason for including that question, to remind you to think about whether you're working at the population level or individual level. That should tell you which of your answers to use.

Think of this question as three separate questions. Could your teacher still ask you the last question if you did not have the first two (assuming you still know you are working with sickle cell anemia)?

Yes, you could.

So now using ONLY the information in the 3rd question, can you figure out the answer?

## 1. What is the Hardy-Weinberg Equilibrium?

The Hardy-Weinberg Equilibrium (HWE) is a mathematical model that describes the genetic equilibrium of a population over generations. It predicts the frequencies of alleles and genotypes in a population that is not evolving.

## 2. What are the assumptions of the Hardy-Weinberg Equilibrium?

The assumptions of HWE include a large population size, random mating, no mutations, no migration, and no natural selection. These assumptions allow for the prediction of allele and genotype frequencies in a stable population.

## 3. How is the Hardy-Weinberg Equilibrium calculated?

The equation for HWE is p2 + 2pq + q2 = 1, where p and q represent the frequencies of the two alleles in a population. p2 represents the frequency of homozygous dominant individuals, 2pq represents the frequency of heterozygous individuals, and q2 represents the frequency of homozygous recessive individuals.

## 4. What is the significance of the Hardy-Weinberg Equilibrium?

The HWE model is important in population genetics as it allows scientists to compare observed allele and genotype frequencies to those predicted by the model. Deviations from HWE can indicate evolutionary forces such as natural selection, genetic drift, or gene flow.

## 5. How is the Hardy-Weinberg Equilibrium used in research?

The HWE model is used in research to study the genetic structure of populations and to determine if a population is evolving. It can also be used to estimate the probability of inheriting genetic diseases and to track changes in allele frequencies over time.

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