EBK ESSENTIALS OF GENETICS
EBK ESSENTIALS OF GENETICS
9th Edition
ISBN: 9780134190068
Author: Palladino
Publisher: YUZU
bartleby

Videos

Textbook Question
Chapter 12, Problem 1CS

CASE STUDY | A drug that sometimes works

A 30-year-old woman with β-thalassemia, a recessively inherited genetic disorder caused by absence of the hemoglobin β chain, had been treated with blood transfusions since the age of 7. However, in spite of the transfusions, her health was declining. As an alternative treatment, her physician administered 5-azacytidine to induce transcription of the fetal β hemoglobin chain to replace her missing β chain. This drug activates gene transcription by removing methyl groups from DNA. Addition of methyl groups silences genes. However, the physician expressed concern that approximately 40 percent of all human genes are normally silenced by methylation. Nevertheless, after several weeks of 5-azacytidine treatment, the patient's condition improved dramatically. Although the treatment was successful, use of this drug raises several important questions.

Why was her physician concerned that a high percentage of human genes are transcriptionally silenced by methylation?

Expert Solution & Answer
Check Mark
Summary Introduction

Case summary:

A 30-year-old woman with β-thalassemia had been treated with a blood transfusion since the age of 7. In spite of transfusions, her health was declining. So, in order to improve the health, her physician gave her 5-azacytidine to induce transcription of fetal β hemoglobin chain to replace the missing β chain.

Characters in the case:

A 30-year-old woman with a recessively inherited genetic disorder called β-thalassemia.

Adequate information:

Her health was declining in spite of transfusions and her physician gave her alternative treatment of 5-azacytidine for the induction of transcription of fetal β hemoglobin. This drug helps in activating transcription of genes by removing methyl groups.

To determine: The concern of the physician about the fact that a high percentage of human genes is transcriptionally silenced by methylation.

Explanation of Solution

Given the information:

Addition of methyl groups silences approximately 40% (percent) of all human genes by methylation.

Beta thalassemia is a recessively inherited genetic disorder. This disorder is characterized by the reduction in the production of beta chains of the hemoglobin molecule. The person suffering from this disorder is not able to produce the hemoglobin in sufficient amount and it leads to the anemic condition of the patient. Hemoglobin is an iron-containing protein of erythrocytes, which helps in carrying the oxygen throughout the whole body. Deficiency in this protein leads to an anemic condition of the body.

In this case, the woman is having β-thalassemia and is cured by regular transfusion of blood. But, her physician provides her with an alternative treatment of 5-azacytidine for induction of fetal β globin genes. This drug is very effective in increasing the synthesis of gamma-globin genes. The production of globin genes by reactivation of fetal globin genes rapidly occurs in bone marrow cells of the patient.

Methylation of DNA (deoxyribonucleic acid) is very necessary for controlling the expression of genes. Methylation of DNA takes place at the globin synthesis site during the treatment. DNA methylation helps in controlling or repressing the gene transcription and helps in the normal development of the body. So, this drug acts by removing the methyl groups from the DNA and thereby activating the transcription of genes responsible for producing fetal β globin genes. So, if a high number of human genes is transcriptionally silenced by methylation, there would be the possibility of production of lethal and mutagenic effects or lesions.

Conclusion

Thus, it can be concluded that the treatment of thalassemia by providing 5-azacytidine is a good option. It enhances the beta globin chains production by silencing the methylation of certain genes.

Want to see more full solutions like this?

Subscribe now to access step-by-step solutions to millions of textbook problems written by subject matter experts!
Students have asked these similar questions
4A. In the human gene for the beta chain of haemoglobin (the oxygen-carrying protein in the red blood cells), the first 30 nucleotides in the amino-acid-coding region is represented by the sequence: 3'-TACCACGTGGACTGAGGACTCCTCTTCAGA-5'.   What is the sequence of the partner strand?                                                                                                    4B. If the DNA duplex for the beta chain of haemoglobin above were transcribed from left to right, deduce the base sequence of the RNA in this coding region.
1) Histone methylation can have many different effects on gene expression. In some cases, histone methylation is associated with activation of transcription, whereas in other cases it can trigger the formation of heterochromatin and a decrease in transcription. If histone methylation has been detected in the region of gene YFG in yeast, describe an experiment that could distinguish whether the methylation is important to activate or repress transcription of gene YFG.   2) An E. coli strain of chromosomal genotype lacI lacP lacO lacZ lacY . You wish to transform this strain into a wild-type lac operon by the addition of an extra piece of DNA (plasmid). What regulatory region(s), gene or genes would you add on this extra DNA that would make this strain express the lac operon genes as wild type?  How would you design this plasmid if you want the strain of E. coli to express the lac operon genes even if lactose is absent in the medium (constitutively)?
1. in a TATAT sequence, would the number of sequences similar to a promoter increase or decrease if variation occurred? 2. false promoters are segments that would bind to RNA polymerases but are not associated with genes. is it possible for false promoters to be found in the human genome?

Chapter 12 Solutions

EBK ESSENTIALS OF GENETICS

Knowledge Booster
Biology
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.
Similar questions
  • Mutant #    Deletion Region    %Transcription (lungs)  %Transcription(kidneys) WT                      None                     100%                                      100%  1                          1-200                    130%                                       130% 2                       250-400                   100%                                       100% 3                       500-800                     50%                                         50% 4                      950-1100                      0%                                        100%   1) For the following gene, you notice the following results when analyzing several muntants. What type of sequence (be specific) has been mutated in mutant 1? What type of sequence (be specific) has been mutated in mutant 3? What would we call this type of mutation?  What type of sequence (be specific) has been mutated in mutant 4?
    1).   In the absence of this enzyme, a substance called ceroid lipofuscin accumulates in lysosomes in the brain, resulting in seizures, blindness, decline in cognitive function and motor skills, dementia, and death by the late teens or early 20’s. The TPP1 gene is 6695 bp in length. Think about the characteristics of Batten disease, and then suggest an approach to gene therapy that might be effective for this specific genetic disorder.  You may assume that your research team is working in the U.S. and your research is funded by a grant from the National Institutes of Health (NIH).   a) Hypothetically, what specific type of VECTOR will you use to perform your gene therapy? Please select from the following list of potential vectors: disabled retrovirus, adenovirus, adeno-associated virus (AAV), or herpes simplex virus (HSV), then give two reasons why this specific vector is the most appropriate for your gene therapy. Please explain why you were able to rule out the other potential…
    1).   In the absence of this enzyme, a substance called ceroid lipofuscin accumulates in lysosomes in the brain, resulting in seizures, blindness, decline in cognitive function and motor skills, dementia, and death by the late teens or early 20’s. The TPP1 gene is 6695 bp in length. Think about the characteristics of Batten disease, and then suggest an approach to gene therapy that might be effective for this specific genetic disorder.  You may assume that your research team is working in the U.S. and your research is funded by a grant from the National Institutes of Health (NIH).  Other scientists have suggested that it might be possible to use CRISPR to treat this genetic disorder in affected individuals.      (i) First, what is CRISPR? (BRIEFLY describe what it is and how it works).      (ii) Briefly describe how CRISPR could be utilized in treating genetic conditions such as Batten disease.
    • SEE MORE QUESTIONS
    Recommended textbooks for you
  • Biology: The Dynamic Science (MindTap Course List)
    Biology
    ISBN:9781305389892
    Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan
    Publisher:Cengage Learning
    Biology 2e
    Biology
    ISBN:9781947172517
    Author:Matthew Douglas, Jung Choi, Mary Ann Clark
    Publisher:OpenStax
  • Biology: The Dynamic Science (MindTap Course List)
    Biology
    ISBN:9781305389892
    Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan
    Publisher:Cengage Learning
    Biology 2e
    Biology
    ISBN:9781947172517
    Author:Matthew Douglas, Jung Choi, Mary Ann Clark
    Publisher:OpenStax
    QCE Biology: Introduction to Gene Expression; Author: Atomi;https://www.youtube.com/watch?v=a7hydUtCIJk;License: Standard YouTube License, CC-BY