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Questions and Answers

What is the cause of Turner syndrome?

  • Chromosomal translocation
  • Inherited genetic mutation
  • Anaphase lag during early mitotic division (correct)
  • Anaphase lag during gametogenesis

In Turner syndrome, what is the result of classical monosomy X (45,X)?

  • No specific phenotype
  • Male phenotype
  • Intersex phenotype
  • Female phenotype (correct)

What is the main cause of mosaic Turner syndrome (45X/46XX or 45X/46XY)?

  • Genetic recombination
  • Parental inheritance
  • Somatic mutation
  • Chromosomal nondisjunction (correct)

Which cells express X chromosome from the mother and which from the father in female mosaics?

<p>Some cells express X from mother, some express X from father (B)</p> Signup and view all the answers

Which genetic condition is associated with incomplete X-inactivation, leading to up to 25% of X chromosome genes escaping inactivation?

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

In which genetic condition can tetragametic chimerism lead to implications for paternity testing and genetic inheritance?

<p>Turner Syndrome (C)</p> Signup and view all the answers

Which genetic condition involves an individual with two or more populations of cells with different genotypes that arose from a single fertilized egg?

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

Which genetic phenomenon involves the switching on or off of specific alleles, with implications for gene expression and disease development?

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

Which genetic condition is associated with IGF2 gene imprinting important for regulating growth during gestation and preventing cancer development?

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

Which genetic condition is associated with diseases related to imprinting due to uniparental disomy (UPD), mutations in the imprinting control center, or deletions/mutations of the genes on the relevant chromosome?

<p>Prader-Willi Syndrome (B)</p> Signup and view all the answers

Which syndrome is associated with paternal uniparental disomy for Chromosome 15, resulting in the absence of the maternal chromosome?

<p>Prader-Willi Syndrome (A)</p> Signup and view all the answers

Which syndrome is associated with differences in gene expression depending on the parental origin of the affected chromosome?

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

Which genetic condition involves addressing the impact of infertility and the transition of young people to adult care in genetic counseling?

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

Which genetic condition management includes screening for comorbidities such as heart problems, scoliosis, and high blood pressure, as well as hormone and infertility treatments?

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

Which genetic condition involves karyotype analysis, cardiac function tests, and imaging tests like CT, MRI, and MRA as key investigations?

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

Which syndrome is associated with X-inactivation that is incomplete, leading to up to 25% of X chromosome genes escaping inactivation?

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

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Study Notes

Chimaerism, Mosaicism, and Imprinting in Genetics

  • Turner Syndrome (TS) management includes screening for comorbidities such as heart problems, scoliosis, and high blood pressure, as well as hormone and infertility treatments.
  • Key investigations for TS include karyotype analysis, cardiac function tests, and imaging tests like CT, MRI, and MRA.
  • Genetic counseling for TS includes addressing the impact of infertility and the transition of young people with TS to adult care.
  • X-inactivation in TS is incomplete, leading to up to 25% of X chromosome genes escaping inactivation, affecting gene dosing and contributing to the female phenotype.
  • A scenario involving tetragametic chimerism is described, where an individual, Mr. X, has cells with two different genomes, leading to implications for paternity testing and genetic inheritance.
  • Chimaerism occurs when an individual has two or more populations of cells with different genotypes due to the fusion of more than one fertilized zygote during embryogenesis.
  • Mosaicism refers to an individual with two or more populations of cells with different genotypes that arose from a single fertilized egg, which can be somatic or germline.
  • Imprinting, exemplified by the case of Robert Draper, involves the switching on or off of specific alleles, with implications for gene expression and disease development.
  • IGF2 gene imprinting is important for regulating growth during gestation and preventing cancer development, such as Wilms' tumor associated with loss of imprinting.
  • Angelman and Prader-Willi syndromes are associated with imprinting errors, with differences in gene expression depending on the parental origin of the affected chromosome.
  • Paternal uniparental disomy for Chromosome 15 results in Angelman's syndrome due to the absence of the maternal chromosome.
  • Diseases related to imprinting can occur due to uniparental disomy (UPD), mutations in the imprinting control center, or deletions/mutations of the genes on the relevant chromosome.

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