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Questions and Answers
A genetic disorder is caused by a mutation on the X chromosome and is expressed in both homozygous females and hemizygous males. Which type of inheritance pattern does this disorder follow?
A genetic disorder is caused by a mutation on the X chromosome and is expressed in both homozygous females and hemizygous males. Which type of inheritance pattern does this disorder follow?
In an autosomal recessive inheritance pattern, what is the probability of two carrier parents having a child with the disorder?
In an autosomal recessive inheritance pattern, what is the probability of two carrier parents having a child with the disorder?
A genetic disorder is caused by a mutation on one of the 22 pairs of autosomes. The disorder is expressed in individuals who inherit only one copy of the mutated gene. How is this inheritance pattern described?
A genetic disorder is caused by a mutation on one of the 22 pairs of autosomes. The disorder is expressed in individuals who inherit only one copy of the mutated gene. How is this inheritance pattern described?
A man with a sex-linked dominant disorder has children with a woman who does not carry the mutation. What is the probability that their son will inherit the disorder?
A man with a sex-linked dominant disorder has children with a woman who does not carry the mutation. What is the probability that their son will inherit the disorder?
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Which of the following statements is TRUE about autosomal recessive inheritance?
Which of the following statements is TRUE about autosomal recessive inheritance?
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What is the difference between autosomal dominant and autosomal recessive inheritance?
What is the difference between autosomal dominant and autosomal recessive inheritance?
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A woman with a sex-linked recessive disorder marries a man who does not carry the mutation. What is the probability that their daughter will inherit the disorder?
A woman with a sex-linked recessive disorder marries a man who does not carry the mutation. What is the probability that their daughter will inherit the disorder?
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Why is it important to understand the different inheritance patterns for genetic disorders?
Why is it important to understand the different inheritance patterns for genetic disorders?
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A specific mutation in a gene causes a disorder, but only 70% of individuals carrying this mutation actually develop symptoms. This is an example of:
A specific mutation in a gene causes a disorder, but only 70% of individuals carrying this mutation actually develop symptoms. This is an example of:
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What are the chances of a daughter inheriting an X-linked recessive disorder from her father?
What are the chances of a daughter inheriting an X-linked recessive disorder from her father?
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Which of the following genetic disorders is NOT associated with an autosomal dominant mode of inheritance?
Which of the following genetic disorders is NOT associated with an autosomal dominant mode of inheritance?
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Which of the following is NOT a key component of an accurate family history for determining genetic risks?
Which of the following is NOT a key component of an accurate family history for determining genetic risks?
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Individuals with cystic fibrosis (CF) are more likely to be susceptible to infections, but they also have a higher resistance to:
Individuals with cystic fibrosis (CF) are more likely to be susceptible to infections, but they also have a higher resistance to:
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Which of the following disorders is NOT known to have a strong familial history?
Which of the following disorders is NOT known to have a strong familial history?
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Which of the following genes is associated with increased risk of colorectal cancer?
Which of the following genes is associated with increased risk of colorectal cancer?
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A genetic disorder that exhibits anticipation is characterized by:
A genetic disorder that exhibits anticipation is characterized by:
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Flashcards
Autosomal Dominant
Autosomal Dominant
A trait expressed with only 1 copy of a mutated gene, found on non-sex chromosomes.
Autosomal Recessive
Autosomal Recessive
A trait requiring 2 copies of a mutated gene to be expressed, commonly seen in single generational families.
Sex-Linked Dominant
Sex-Linked Dominant
A dominant trait caused by a mutation on the X chromosome, expressed in females (heterozygous) and males (hemizygous).
Sex-Linked Recessive
Sex-Linked Recessive
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Heterozygous Female
Heterozygous Female
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Hemizygous Male
Hemizygous Male
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Dominant vs Recessive Inheritance
Dominant vs Recessive Inheritance
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Parent Carrier Probability
Parent Carrier Probability
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Heterozygote Advantage
Heterozygote Advantage
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Familial Disorders
Familial Disorders
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Key Components of Family History
Key Components of Family History
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BRCA1 and BRCA2
BRCA1 and BRCA2
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Penetrance
Penetrance
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Anticipation
Anticipation
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Study Notes
Mendelian Inheritance
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Autosomal Dominant: A trait or disorder where the phenotype is expressed with only one copy of the mutated gene. A single copy causes the disorder. 50% chance of inheriting the mutation. Seen across generations.
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Autosomal Recessive: A trait or disorder needing two copies of the mutated gene to be expressed. 25% chance of inheriting mutation from carrier parents. Seen in single generational families. Both parents must be carriers, but typically are heterozygous and don't express the mutation themselves. Both parents in dominant and recessive cases are equally able to transmit the disorder.
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Sex-Linked Dominant: A dominant trait or disorder caused by a mutation on the X chromosome. Expressed in heterozygous females and hemizygous males. Heterozygous females have two different versions of the gene, inherited by each parent. Hemizygous males have one affected gene, since males only inherit one X chromosome. Affected males pass the dominant gene to all their daughters, but none of their sons. Affected females have a 50% chance of passing the gene to their children.
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Sex-Linked Recessive: A recessive disorder caused by a mutation on the X chromosome. Expressed in homozygous females (two copies of the mutation) and hemizygous males (one copy of the mutation). Males affected always have affected females as ancestors. Male-to-male transmission does not happen.
Calculating Probability of Passing Genetic Disorders
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Autosomal Dominant: 50% chance of passing the gene to a child.
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Autosomal Recessive: If both parents are carriers, there's a 25% chance of passing the gene.
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X-Linked Dominant: 50% chance of passing the gene to the child.
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X-Linked Recessive: Carrier mothers have a 50% chance of passing the mutated gene to their children. This includes a 50% chance that a son will be affected and a 50% chance a daughter will be a carrier. Fathers with the X-linked disorder always pass it to their daughters, but never to their sons.
Heterozygote Advantage
- Heterozygote individuals have a higher chance of survival against certain diseases. They may lack enough genetic disease compared to homozygous people. Examples include sickle cell trait and cystic fibrosis.
Familial History of Disorders
- Certain disorders (e.g., CAD, stroke, cancer, diabetes, pulmonary conditions, mental illness) have a strong familial history.
Components of an Accurate Family History for Genetic Risks
- Assessing any diagnosed diseases in family members (especially blood relatives like parents and siblings).
- Ethnicity.
- Age of onset of conditions.
- Affected family members on both sides of the family.
Genomics and Healthcare
- Genomics is impacting healthcare through early identification of susceptible individuals.
- It allows for development of targeted treatments, and more precise disease predictions.
Key Genetic Terms
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Penetrance: The proportion of individuals with a mutation showing the clinical symptoms. Typically used for dominant disorders.
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Anticipation: A tendency for genetic disorders to present earlier or more severely in successive generations.
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Consanguinity: Genetic relatedness (shared ancestors) between individuals with common ancestors.
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Genotype: The complete set of genetic material.
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Phenotype: Observable physical or biochemical characteristics resulting from the genotype.
Mutations and Diseases
- BRCA1 and BRCA2: Associated with hereditary breast and ovarian cancer (autosomal dominant).
- Colorectal cancer (APC): Associated with hereditary nonpolyposis colorectal cancer (HNPCC), from mismatch repair genes (MSH2, MLH1, MSH6, PMS2). Autosomal dominant manner.
Epigenetics
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Epigenetics involves chemical modifications to DNA that affect gene expression, and is influenced by environment.
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Internal influences are things like hormones, cellular differentiation, developmental stage, and age.
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External influences are factors like diet, toxins, stress, physical activity, and social interactions.
CRISPR and Gene Editing
- CRISPR and gene editing have benefits for targeting genetic diseases, cancer treatment, organ transplantation, and disease prevention. But have risks too, of off-target edits and unforeseen consequences; as well as ethical concerns.
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Description
Explore the key concepts of Mendelian inheritance in this quiz. Test your understanding of autosomal dominant, autosomal recessive, and sex-linked traits. Learn how these inheritance patterns affect the expression of genetic disorders across generations.
