Genetics and Epigenetics Quiz
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What is a common characteristic of an ovarian teratoma?

  • It typically contains fetal tissue with two paternal genomes.
  • It consists of disorganized placental tissue.
  • It is a common pregnancy complication.
  • It can contain tissues derived from all three germ layers, like hair and teeth. (correct)

    • Hydatidiform moles typically have two maternal genomes.

    False (B)

    What epigenetic process is unique to mammals (and some flowering plants) and explains why mammals cannot develop parthenogenetically?

    genomic imprinting

    In the imprinting cycle, maternal imprints are established in the growing ______.

    <p>oocyte</p> Signup and view all the answers

    Match the following terms with their descriptions:

    <p>Ovarian teratoma = Benign tumor with tissues from all three germ layers Hydatidiform mole = Disorganized mass of placental tissue without a fetus Genomic imprinting = Epigenetic process unique to mammals Parthenogenesis = Development from an unfertilized egg</p> Signup and view all the answers

    Which of the following best describes the loss/gain of expression in an ovarian teratoma?

    <p>Loss of naturally paternally expressed genes and gain of normally maternally expressed genes (C)</p> Signup and view all the answers

    Global demethylation and erasure of parental imprints in the developing germline occurs in early post-implantation stage.

    <p>True (A)</p> Signup and view all the answers

    Which of the following best describes the function of DNMT1?

    <p>Maintains DNA methylation at imprinted control regions (ICs). (D)</p> Signup and view all the answers

    The H19DMR is methylated in oocytes.

    <p>False (B)</p> Signup and view all the answers

    What is the function of the gene IGF2?

    <p>Promotes cell division and growth</p> Signup and view all the answers

    The maternally expressed gene, CDKN1C, encodes a cell cycle ______.

    <p>inhibitor</p> Signup and view all the answers

    Match the following syndromes with their descriptions.

    <p>Beckwith-Wiedemann Syndrome = Fetal overgrowth syndrome. Silver-Russell Syndrome = Not described in the text Prader-Willi Syndrome = Not described in the text Angelman Syndrome = Not described in the text</p> Signup and view all the answers

    Which of these is a typical characteristic of babies with Beckwith-Wiedemann Syndrome (BWS)?

    <p>Babies in the 95th weight percentile at birth. (C)</p> Signup and view all the answers

    In a patient with paternal disomy of human chromosome 11p15, there would be two copies of the CDKN1C gene present, one from each parent.

    <p>False (B)</p> Signup and view all the answers

    What does KvDMR1 control?

    <p>Imprinted expression of CDKN1C and several additional maternally expressed gene</p> Signup and view all the answers

    The H19DMR controls the imprinted expression of which two genes ______ and ______?

    Signup and view all the answers

    Which of the following is the most common epigenetic alteration associated with Beckwith-Wiedemann Syndrome (BWS)?

    <p>Loss of DNA methylation at KvDMR1 (B)</p> Signup and view all the answers

    Silver-Russell Syndrome (SRS) always results from maternal disomy of human chromosome 11p15.

    <p>False (B)</p> Signup and view all the answers

    What are two common features of Silver-Russell Syndrome (SRS) related to growth?

    <p>Low birth weight and poor postnatal growth</p> Signup and view all the answers

    In Beckwith-Wiedemann Syndrome, there is often too much IGF2 and/or too little _______.

    <p>CDKN1C</p> Signup and view all the answers

    Besides maternal disomy, which of the following has been seen to occur in patients diagnosed with Silver Russel Syndrome?

    <p>Maternal uniparental disomy for chromosome 7 (C)</p> Signup and view all the answers

    Most imprinting disorders are inherited from a parent.

    <p>False (B)</p> Signup and view all the answers

    Match the following syndrome with its description regarding the expression of IGF2 and CDKN1C:

    <p>Beckwith-Wiedemann Syndrome = Too much IGF2 and/or too little CDKN1C Silver-Russell Syndrome = Too little IGF2 and/or too much CDKN1C</p> Signup and view all the answers

    What is the OMIM number associated with Silver-Russell Syndrome?

    <p>180860</p> Signup and view all the answers

    What does a loss of DNA methylation at the KvDMR locus typically cause?

    <p>Loss of expression of CDKN1C (A)</p> Signup and view all the answers

    Silver-Russell Syndrome is a fetal growth _____ disorder.

    <p>restriction</p> Signup and view all the answers

    Which of the following is a widely observed early step in human tumorigenesis?

    <p>Genomic hypomethylation and site-specific hypermethylation (C)</p> Signup and view all the answers

    Melanoma nuclei cannot be reprogrammed to create ES cells resulting in 'normal' mice.

    <p>False (B)</p> Signup and view all the answers

    What is the term used to describe non-communicable diseases related to metabolic, cardiovascular, and mental function?

    <p>NCDs</p> Signup and view all the answers

    Adversity, including diet and stress, impacts the fetus and _________ during development.

    <p>placenta</p> Signup and view all the answers

    Match the following with the appropriate description:

    <p>German Blockade = Cut off food and fuel shipments Hongerwinter = Dutch Famine of 1944-1945 Famine Deaths = At least 22,000 Calorie intake = 400 to 800 calories/day for pregnant women</p> Signup and view all the answers

    In the context of genomic imprinting, what does 'parent-of-origin' refer to?

    <p>Whether the gene was inherited from the mother or father. (A)</p> Signup and view all the answers

    A mutation in a gene that acts as a dominant mutation after maternal transmission will always be dominant when paternally transmitted.

    <p>False (B)</p> Signup and view all the answers

    What are the two reciprocal imprinting disorders mentioned in the text?

    <p>Angelmann Syndrome and Prader Willi Syndrome</p> Signup and view all the answers

    In cancer, alterations in genes like ______ and tumor suppressors are thought to initiate the disease

    <p>oncogenes</p> Signup and view all the answers

    Match the following terms related to inheritance patterns:

    <p>Autosomal dominant (maternal transmission) = Acts as a dominant mutation after being inherited from the mother Recessive (paternal transmission) = Acts like a silent mutation after paternal transmission X-linked dominant = Affected individuals usually have at least one parent who is also affected X-linked recessive = More common in males who only have one X chromosome</p> Signup and view all the answers

    What is a characteristic of genomic imprinting disorders?

    <p>They can depend on parent-of-origin. (A)</p> Signup and view all the answers

    In X-linked inheritance, the mode of transmission and inheritance is not sex-specific.

    <p>False (B)</p> Signup and view all the answers

    What is the main cause of cancer according to the text?

    <p>Alterations in genes that regulate cell survival and proliferation</p> Signup and view all the answers

    CDKN1C point mutations are associated with ______, while microduplications are associated with SRS.

    <p>BWS</p> Signup and view all the answers

    Which of the following is NOT a characteristic of genomic imprinting disorders?

    <p>Strictly follow the Mendelian patterns of inheritance. (C)</p> Signup and view all the answers

    Which of the following genes is expressed only from the paternal allele?

    <p>IGF2 (D)</p> Signup and view all the answers

    What is the primary function of CDKN1C?

    <p>cell cycle inhibitor</p> Signup and view all the answers

    In Beckwith-Wiedemann Syndrome (BWS), babies are often in the ______ weight percentile at birth.

    <p>95th</p> Signup and view all the answers

    Match the following genes with their function:

    <p>IGF2 = Promotes cell division and growth CDKN1C = Inhibits cell division and growth H19 = Non-coding RNA LIT1 = Non-coding RNA</p> Signup and view all the answers

    Which of the following is NOT a typical feature of Beckwith-Wiedemann Syndrome (BWS)?

    <p>Microglossia (B)</p> Signup and view all the answers

    KvDMR1 is methylated in sperm.

    <p>False (B)</p> Signup and view all the answers

    What is the function of the H19DMR?

    <p>controls imprinted expression of IGF2 and H19</p> Signup and view all the answers

    In a patient with paternal disomy of human chr. 11p15, how many copies of the IGF2 gene would be present and expressed?

    <p>Two copies, expressed (A)</p> Signup and view all the answers

    Study Notes

    Epigenetics and Underlying Principles

    • The lecture is part of a module titled "Concepts of Disease" (BI2332).
    • The module co-ordinator is Dr. Prytherch.
    • The lecture focuses on epigenetics and its underlying principles.
    • The speaker is Professor Ros John, Head of the Biomedicine Division.

    Genomic Imprinting

    • A lecture called "Human Epigenetics lecture 4" focused on genomic imprinting.
    • The concept of genomic imprinting helps explain why mammals cannot develop parthenogenetically.
    • Imprinted genes account for 0.4% of mammalian genes.
    • These genes are differently expressed depending on whether they come from the mother (M) or father (P).

    Benign Ovarian Teratoma

    • A rare germ cell tumor.
    • Consists of tissues derived from all three germ layers.
    • Often contains hair, sebaceous glands, skin, and teeth.
    • Most are benign.
    • Characterized by two maternal genomes.

    Hydatidiform Mole

    • A rare gestational trophoblastic disorder.
    • Occurs in approximately one in every 1,200 pregnancies.
    • Characterized by disorganized placental tissue without a fetus.
    • Most cases are benign.
    • Characterized by two paternal genomes.

    Mammalian Development

    • For normal mammalian development, two parental genomes are essential.

    Genomic Imprinting Diagrams

    • Diagrams illustrate the concept of biallelic and imprinted genes, showing which allele is expressed (maternal or paternal).
    • Diagrams show how the expression pattern differs in normal cells, ovarian teratomas, and hydatidiform moles.
    • Teratomas exhibit loss of expression of normally paternally expressed genes, but gain in expression of maternally expressed genes.
    • Hydatidiform moles show the opposite pattern, gaining expression of paternally expressed genes, and losing expression of maternally expressed genes.

    Genomic Imprinting Disorders

    • List of disorders associated with genomic imprinting:
      • Beckwith-Wiedemann Syndrome (BWS)
      • Silver-Russell Syndrome (SRS)
      • Prader-Willi Syndrome
      • Angelman Syndrome

    Human Chromosome 11p15

    • Chromosome 11p15 contains imprinted genes.
    • Several genes are expressed only from the maternal allele (red).
    • Others are expressed only from the paternal allele (blue).
    • Some genes are non-coding RNA (H19 and Lit1).
    • This chromosome has two differentially methylated regions (DMRs).

    Differentially Methylated Regions (DMRs)

    • H19 DMR is methylated in sperm.
    • H19 DMR controls imprinted expression of IGF2 and H19.
    • KvDMR1 is methylated in oocytes.
    • KvDMR1 controls imprinted expression of CDKN1C and other maternally expressed genes.

    Insulin-like Growth Factor 2 (IGF2)

    • Paternally expressed gene IGF2 encodes insulin-like growth factor 2.
    • IGF2 is a growth factor promoting cell division and growth.

    Cyclin-dependent Kinase Inhibitor 1C (CDKN1C)

    • Maternally expressed gene CDKN1C encodes cyclin-dependent kinase inhibitor 1C.
    • CDKN1C is a cell cycle inhibitor that inhibits cell division and growth.

    Beckwith-Wiedemann Syndrome (BWS)

    • OMIM 130650 affects 1 in 13,700 births.
    • Characterized by fetal overgrowth syndrome, macrosomia, macroglossia, omphalocele, and predisposition to Wilms' tumor..
    • Some patients have paternal disomy of human chromosome 11p15.
    • Point mutations, translocations, and loss of DNA methylation can contribute to BWS.

    Silver-Russell Syndrome (SRS)

    • OMIM 180860, affects 1 out of 100,000 births.
    • Fetal growth restriction disorder with low birth weight.
    • Some patients have maternal disomy of human chromosome 11p15.
    • Characterized by asymmetry, lack of subcutaneous fat, night sweats.

    Mode of Inheritance

    • Most imprinting disorders arise from de novo mutations.
    • Some inherited genetic mutations, like CDKN1C point mutations in BWS and micro-duplications in SRS, are possible.
    • Imprinting disorders may exhibit unique family patterns different from classic Mendelian inheritance.
    • Some disorders may act as autosomal dominant, or recessive, due to maternal or paternal transmission.

    Angelman and Prader-Willi Syndromes

    • These are also reciprocal imprinting disorders

    Genomic Imprinting Disorders - General Traits

    • Involve genetic and epigenetic mutations.
    • May affect multiple genes.
    • Not always simply a loss of gene expression.
    • Can have dominant inheritance but present as recessive.
    • Can skip generations.
    • Determined by the parent-of-origin.

    Cancer

    • Generally, cancer is a genetic disorder caused by changes in oncogenes and tumor suppressor genes regulating proliferation and survival.
    • Genomic hypomethylation and site-specific hypermethylation are frequently observed in early stages of tumorigenesis.

    Developmental Origins of Disease

    • Non-communicable diseases linked to metabolic, cardiovascular, and mental functions are strongly influenced by early life events.
    • Diseases often become more prevalent in individuals with early-life adversity affecting the fetus and placenta.
    • Examples such as the Dutch famine illustrate the impact of adverse environments.

    Environmental Programming

    • Environmental influences during development (e.g., maternal diet) can alter epigenetic marks, leading to observable phenotypic differences.
    • Identical mice can exhibit differences in coat color due to epigenetic differences in their early development, a hallmark of environmental programming.

    Exposure to Maternal Smoking in Pregnancy & Altered DNA Methylation

    • Maternal smoking during pregnancy is linked to altered DNA methylation in children later in life.

    Epidrugs

    • Histone deacetylases (HDACs) remove acetyl groups from chromatin.
    • DNA methylation inhibitors remove DNA methylation.
    • Researchers are investigating using such enzymes as drugs to reactivate silent genes in vivo.

    DNMT Inhibitors

    • Azacitidine (Vidaza) is an FDA-approved DNMT inhibitor, used to treat myelodysplastic syndrome.
    • It works by reversing DNA methylation in cancer cells.

    Learning Outcomes/Summary

    • Loss or inappropriate addition of DNA methylation can lead to epigenetic disorders.
    • Epigenetic disorders cannot be detected by simple DNA sequencing.
    • Classic epigenetic processes like X-inactivation and genomic imprinting have distinct inheritance patterns distinct from Mendelian inheritance.
    • Environmental factors like diet and stress can influence epigenetic marks.
    • Epigenetic diseases may be potentially reversible using epigenetic modifying drugs (epidrugs)

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    Concepts of Disease (BI2332) Epigenetics Lectures 4 PDF

    Description

    Test your knowledge on ovarian teratomas and their characteristics, imprinting cycles, and the unique epigenetic processes in mammals. This quiz also covers important syndromes related to genetic imprinting and function of specific genes. Dive into the fascinating world of genetics!

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