16 Questions
What is the cause of Turner syndrome?
Anaphase lag during early mitotic division
In Turner syndrome, what is the result of classical monosomy X (45,X)?
Female phenotype
What is the main cause of mosaic Turner syndrome (45X/46XX or 45X/46XY)?
Chromosomal nondisjunction
Which cells express X chromosome from the mother and which from the father in female mosaics?
Some cells express X from mother, some express X from father
Which genetic condition is associated with incomplete X-inactivation, leading to up to 25% of X chromosome genes escaping inactivation?
Turner Syndrome
In which genetic condition can tetragametic chimerism lead to implications for paternity testing and genetic inheritance?
Turner Syndrome
Which genetic condition involves an individual with two or more populations of cells with different genotypes that arose from a single fertilized egg?
Mosaicism
Which genetic phenomenon involves the switching on or off of specific alleles, with implications for gene expression and disease development?
Imprinting
Which genetic condition is associated with IGF2 gene imprinting important for regulating growth during gestation and preventing cancer development?
Turner Syndrome
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?
Prader-Willi Syndrome
Which syndrome is associated with paternal uniparental disomy for Chromosome 15, resulting in the absence of the maternal chromosome?
Prader-Willi Syndrome
Which syndrome is associated with differences in gene expression depending on the parental origin of the affected chromosome?
Angelman Syndrome
Which genetic condition involves addressing the impact of infertility and the transition of young people to adult care in genetic counseling?
Turner Syndrome
Which genetic condition management includes screening for comorbidities such as heart problems, scoliosis, and high blood pressure, as well as hormone and infertility treatments?
Turner Syndrome
Which genetic condition involves karyotype analysis, cardiac function tests, and imaging tests like CT, MRI, and MRA as key investigations?
Turner Syndrome
Which syndrome is associated with X-inactivation that is incomplete, leading to up to 25% of X chromosome genes escaping inactivation?
Turner Syndrome
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.
Test your knowledge of genetic phenomena like chimaerism, mosaicism, and imprinting. Explore the management, investigations, and genetic counseling related to Turner Syndrome, as well as the implications of X-inactivation. Delve into real-life cases and their impact on gene expression, disease development, and inheritance patterns.
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