Videos
CASE STUDY | Timing is everything
A man in his early 20s received chemotherapy and radiotherapy as treatment every 60 days for Hodgkin disease. After unsuccessful attempts to have children, he had his sperm examined at a fertility clinic, upon which multiple chromosomal irregularities were discovered. When examined within 5 days of a treatment, extra chromosomes were often present or one or more chromosomes were completely absent. However, such irregularities were not observed at day 38 or thereafter.
How might a geneticist explain the time-related differences in chromosomal irregularities?
Case summary:
A male, who suffers from Hodgkin disease receive chemotherapy and radiotherapy treatment every 60 days. His age is in the early 20s and his attempts to have children are unsuccessful. The reason is chromosomal irregularities, which is prominent when he is examined during the first 5 days of treatment.
Characters of the case:
A male patient.
Adequate information:
Hodgkin's disease is a type of cancer which affects lymphatic system and treatment includes radiotherapy and chemotherapy.
To determine:
The time-related chromosomal irregularities during chemotherapy and radiotherapy treatment in a patient suffering from Hodgkin disease.
Explanation of Solution
Given information:
The chromosomal irregularities are not found when examined on or after 38 days of treatment.
The sperm or gamete produced when the person is under treatment is infertile as chemotherapy and radiotherapy can affect healthy cells. The process of meiosis which produces four gametes (sperms) with a haploid number of chromosomes is affected because of high exposure to chemotherapeutic drugs and radiations given during treatment.
Meiosis is the cell division which takes place in germ-line cells which is a layer of undifferentiated cells called spermatogonium present in testes (male reproductive organ). Meiosis produces four haploid gametes or sperms from diploid germ cell which becomes primary spermatocyte to undergo first meiotic division. The product of this division is called secondary spermatocyte which undergoes a second meiotic division to produce spermatids. Spermiogenesis is a specialized process which gives rise to motile sperm with a haploid number of chromosomes.
Sperm produced during the first days of treatment have chromosomal irregularities which include the presence of extra chromosomes or absence of certain chromosomes as the dosage of chemotherapy and radiotherapy affects the germ-line cell division. But at day 38 or thereafter, the dosage level reduces which may not have a direct effect on germ-line cell division. Therefore, chromosomal irregularities are based on the level of exposure to the radiation and chemotherapeutic drugs.
Thus, it can be concluded that the chromosomal irregularities are high during the initial days of treatment as the exposure is high but the level of exposure reduces after 38 days.
Want to see more full solutions like this?
Chapter 2 Solutions
Essentials of Genetics (9th Edition) - Standalone book
- B4. In a woman with translocation of a small chromosomal segment from the chromosome 5 on chromosome 10 and a normal phenotype, prenatal screening is done for the carrying fetus. The woman is 10 weeks pregnant. It is determined that the fetus will have a structural chromosomal abnormality (deficiency) and will manifest mental retardation. A. Detail the procedures followed by the clinician geneticist in order to arrive at the above diagnosis. In which comments supported? B. What is the name of the syndrome that the child will manifest? B3. In different strains of the bacterium E.coli an inability to copied. The following problems were recorded: Strain 1 : Copy not starting. Stem 2 : No primary segment is composed. Strain 3 : Many short DNA segments complementary and antiparallel with parent chains. Strain 4: Many errors in the newly synthesized chains. Indicate regions of the corresponding genome of bacterial strains that may have been mutated with resulting in the above…arrow_forwardFragile X syndrome why is interesting Fragile X syndrome What are the symptoms or characteristics of this disorder or trait? What is the prevalence of the trait or disorder? What are the main genetic factors? s the genetic cause of this disorder or trait known? What gene(s) have been proven to be involved? Or, if not known, what genes are thought to be involved? Is it caused by a single gene? polygenic? Multifactorial? Devote a few paragraphs to this This could be one of the longest parts of the paper, if you choose to focus on this. If multiple genes are thought to be involved, discuss the specific role of at least one of them in depth (if known). Is the gene you’re discussing thought to play a major or a minor role in the phenotype? What chromosome is it on? What protein does it code for, and how might the protein possibly contribute to the phenotype? If no genes have yet been identified, indicate this, and devote at least one paragraph to any current efforts to determine which…arrow_forwardThe woman in Problem 24 has had two miscarriages. She has come to you, an established genetic counselor, with these questions: Is there a genetic explanation of her frequent miscarriages? Should she abandon her attempts to have a child of her own? If not, what is the chance that she could have a normal child? Provide an informed response to her concerns.arrow_forward
- 15- A woman carries the testicular feminization mutation (tfm) on one of her X chromosomes; the other X carries the wild-type allele (Tfm). If the woman marries a normal man, what fraction of her children will be phenotypically male? Assume the chance to have a girl or a boy is equal. a) 1/2 b) 1/8 C) 3/4 d) 3/8 702040 e) 1/4 Boş bırakarrow_forwardX chromosome inactivation in a diploid XX female is not completely inactivated, explain?arrow_forwardHi! I would love to get some help on the box-and arrow model question! :) A male individual who is XYSRY has the following genotype for the AMH gene on chromosome 19: AMH1 AMH2. The AMH1 allele codes for a protein that is capable of binding to the receptor for AMH. The AMH2 allele codes for a protein that is unable to bind with the receptor for AMH. Based on your understanding of biology, what is the likely phenotype of this individual? Humans have 23 pairs of chromosomes of which 22 pairs are autosomal and the 23rd pair is sex-linked.In a human female, the sex chromosome pair is represented as XX, whereas, in a human male, it is represented as XY.AMH is an anti-Mullerin hormone produced by the Sertoli cells in males and helps in the development of the sex organs. Each pair of chromosomes has a pair of genes called alleles at the same loci representing a single character. Each gene of an allele represents the expression of the character.A gene can either show expression or…arrow_forward
- 1. Assume that figure (A) represents a normal karyotype of this animal. What is the diploid number of thisanimal? 2.Cell (A) contains 3.1 billion (3.1 x 109) base pairs of DNA. Each nucleosome has about 200 bp of DNAwrapped around the histone core.a. What is the maximum number of nucleosomes that can be present in the cell?b. What is the maximum number of H2A histone protein molecules that can be present in the cell?arrow_forwardDescribe the molecular process of X-chromosome inactivation.This description should include the three phases of inactivationand the role of the Xic. Explain what happens to the X chromosomes during embryogenesis, in adult somatic cells, and duringoogenesis.arrow_forwardPlease type your answer 1A. What is the molecular basis for genomic imprinting? B. How is the process of X-chromosome inactivation similar to genomic imprinting. C. How is the process of X-chromosome inactivation different from genomic imprinting. D. In mice, the Igf2 gene inherited from the mother is never expressed in her offspring? Explain. E. What genes are deleted in a female born with Angelman syndrome. Which parent transmitted the deletion to her?arrow_forward
- 13 Black coat color (B) in cocker spaniels is dominant to white coat color (b). Solid coat pattern (S) is dominant to spotted pattern (s). The pattern arrangement is located on a different chromosome than the one for color, and its gene segregates independently of the color gene. A male that is black with a solid pattern mates with three females. Indicate the genotypes of the parents. a) The mating with female A, which is white, solid, produces four pups: two black, solid, and two white, solid. b) The mating with female B, which is black, solid, produces a single pup, which is white, spotted. c) The mating with female C, which is white, spotted, produces four pups: one white, solid; one white spotted; one black, solid; one black, spotted.arrow_forwardStandard 2b A male individual who is XYSRY has the following genotype for the AMH gene on chromosome 19: AMH1 AMH2. The AMH1 allele codes for a protein that is capable of binding to the receptor for AMH. The AMH2 allele codes for a protein that is unable to bind with the receptor for AMH. 7. Based on your understanding of biology, what is the likely phenotype of this individual? 8. Create a box-and-arrow model that describes: a. how information in the AMH gene results in the phenotype you identified, above, and b. the origin of the genetic variation in this system. Your model should include the following core structures, contextualize to this case, although you may add or repeat structures as needed: allele, amino acids, gene, nucleotides, phenotype, proteinarrow_forwardPart 3C: Below is data from a pedigree trace of patients affected with mouse model of pancreatic cancer, and below are the observations regarding a new gene called 318 that is found on chromosome 5. Patient II-4 has two copies of loss of function variant alleles (or is homozygous for loss-of-function variant 318 allele). Patient I-2 has one copy of loss of function variant and one copy of unaffected allele (is heterozygous for loss-of-function variant 318 allele). Patient II-1 has two copies of unaffected allele (or is homozygous for unaffected 318 allele). |-1 1-2 Il-1 Il-2 Il-3 |l-4 II-5 II-1 III-2 III-3 Based upon data above, what is the mode of inheritance for mouse model for pancreatic cancer? Why?arrow_forward
Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning