Cytogenetics: Chromosome Disorders and Syndromes
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Questions and Answers

What is the term for a uniform addition of a chromosome to all original pairs?

  • Euploidy (correct)
  • Trisomy
  • Monosomy
  • Aneuploidy

What is the characteristic feature of Trisomy 21?

  • Severe cognitive impairment and physical abnormalities
  • Lymphedema at birth, short stature, and lack of secondary sex characteristics
  • Large tongue, slanting eyes, semi-crease on hands, hypotonia, cardiac delays, and cognitive impairment (correct)
  • Severe malformations and a shorter life span

What is the name of the syndrome caused by an extra chromosome 18?

  • Turner syndrome
  • Edwards syndrome (correct)
  • Klinefelter syndrome
  • Patau syndrome

What is the characteristic feature of X-linked recessive inheritance?

<p>Affected individuals are principally males with symptoms (D)</p> Signup and view all the answers

What is the name of the syndrome caused by an extra X chromosome in males?

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

What is the characteristic feature of X-linked dominant inheritance?

<p>A variant in one copy can cause the disorder in males (A)</p> Signup and view all the answers

What is a characteristic of X-linked traits?

<p>They cannot be passed from fathers to sons. (A)</p> Signup and view all the answers

In an autosomal dominant disorder, what is the minimum number of altered gene copies required for a person to be affected?

<p>One copy in each cell. (B)</p> Signup and view all the answers

What is the chance of a child inheriting a mutant allele and being affected if one of their parents has an autosomal dominant disorder?

<p>50% (C)</p> Signup and view all the answers

What is the chance of a child having a condition if both parents are carriers of an autosomal recessive variant but do not have the condition?

<p>25% (D)</p> Signup and view all the answers

When should the nurse collect the newborn's blood screening for genetic disorders?

<p>After the first feeding is complete and the infant is 24 hours old. (B)</p> Signup and view all the answers

Flashcards

Euploidy definition

Uniform addition of a chromosome to all original pairs.

Trisomy 21 characteristics

Large tongue, slanting eyes, semi-crease on hands, hypotonia, cardiac delays, and cognitive impairment.

Edwards Syndrome cause

Extra chromosome 18.

X-linked recessive inheritance

Primarily affects males, symptoms manifest in males.

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Klinefelter syndrome cause

Extra X chromosome in males.

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X-linked dominant inheritance

A variant in one copy can cause the disorder in males.

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X-linked trait inheritance

Cannot be passed from fathers to sons.

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Autosomal dominant disorder copies

One copy in each cell is sufficient for the disorder.

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Autosomal dominant inheritance chance

50% chance for a child to inherit and be affected.

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Autosomal recessive carrier chance

25% chance for a child to have the condition if both parents are carriers.

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Newborn screening timing

After first feeding, and when the infant is 24 hours old.

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Study Notes

Chromosome Disorders (Cytogenetics)

  • Euploidy: uniform addition of chromosomes to all original pairs
  • Types of euploidy: trisomy and monosomy

Trisomy

  • Trisomy: additional chromosome added to a pair
  • Trisomy 21 (Down syndrome): Chr-47, XX, +21
    • Symptoms: large tongue, slanting eyes, semi-crease on hands, hypotonia, cardiac delays, cognitive impairment
  • Trisomy 18 (Edwards syndrome): Chr-47, XX, +18
    • Symptoms: severe cognitive impairment and physical abnormalities, shorter life span
  • Trisomy 13 (Patau syndrome): Chr-47, XX, +13
    • Symptoms: severe malformations, short life span

Sex Chromosome Aneuploidies

  • Alterations in the number of sex chromosomes
  • Examples: Klinefelter syndrome, Turner syndrome
  • Klinefelter syndrome (47-XXY): gynecomastia, small testes, infertility, long arms/legs
  • Turner syndrome (45-X or 45-X0): lymphedema at birth, short stature, lack of secondary sex characteristics during adolescence, cardiac issues

Inheritance Patterns

  • X-linked Recessive inheritance
    • Affected individuals are principally males
    • Carrier females are normal, males are not carriers
    • Example: Hemophilia
  • X-linked Dominant inheritance
    • Variant in one copy can cause the disorder in males (with one X)
    • Variant can cause the disorder in females (with two X's)
    • Fathers cannot pass X-linked traits to their sons
    • Example: Fragile X Syndrome
  • Autosomal Dominant inheritance
    • One altered gene copy in each cell is sufficient for the disorder
    • Children of an affected parent have a 50% chance of inheriting the mutant allele and being affected
    • Examples: Huntington's disease, Marfan syndrome
  • Autosomal Recessive inheritance
    • Variants occur in both copies of the gene in each cell
    • If both parents are carriers, their kids have a 25% chance of having the condition
    • Examples: Cystic fibrosis, Sickle cell disease

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Description

This quiz covers chromosome disorders, including Euploidy, Trisomy, and various syndromes such as Trisomy 21, Trisomy 18, and Trisomy 13. Identify symptoms, characteristics, and life expectancy of these conditions.

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