For a number of human hereditary conditions, genetic tes...

Question

For a number of human hereditary conditions, genetic testing is available to identify heterozygous carriers. Some heterozygous carrier testing programs are community-based, often as part of an organized effort targeting specific populations in which a disease and carriers of a disease are relatively frequent. For example, carrier genetic testing programs for Tay–Sachs disease target Ashkenazi Jewish populations and sickle cell disease carrier testing programs target African American populations. The testing is usually free or available at minimal cost, the wait time for results is short, and the results are confidential and unavailable to third parties such as insurance companies. Neither the Tay–Sachs nor the sickle cell allele produces serious consequences for heterozygous carriers.

In a broader sense, what is the value of a community-based effort targeting specific populations for selected diseases?

Accepted Answer

Welcome back, everyone. Here's our next question. Hey, Sachs disease is an autism or recessive disorder characterized by nerve cell destruction in the brain and spinal cord. A couple's child has been diagnosed with the disorder. What is the probability that their next child will also have the disorder? Well, when we have a child affected by an autism or recessive disorder, we can reason backwards to the genotype of the parents. Since the child must have inherited a copy of the gene for this disorder from each parent, we know that the parents most both must be hetero six carriers since they are not themselves affected by the disorder. So in this case, we'll label the parents big t the unaffected gene. Little T the recessive Tay Sachs gene. So we can look at our Punnett Square to look for the possibility that their next child would be affected by the disorder, knowing that an affected child would have the genotype. Little R, excuse me, little T little T wrong letter. So let's fill out we have just a simple four square punnett square. I'm going to fill it out with big T little T on the top, big T little T on the left, The two Gina Types of the two Heterosexual Parents. And when we fill in the offspring, we have 1/4 big T big T than two squares, lower left, upper right, which are hetero six carriers like the parents and one square little t little t homesickness recessive. Since that's the genotype for an affected child, that means the probability of the next child being, being homogeneous, recessive, being affected by to say sex disease is 1/4. So when we look over at our answer choices, we see that choice B is 1 4th and that would be our correct answer for the probability that their next child would be affected by TSX disorder. See you in the next video.

Key Concepts

Heterozygous Carriers

Community-Based Genetic Testing

Confidentiality in Genetic Testing

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