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Quizzes > Health & Medicine > Diseases & Conditions

Autosomal Dominant Disorder Quiz: Test Your Genetic Knowledge

Ready to explore autosomal dominant inheritance? Start this genetic disorders quiz now!

Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art style illustration showing dna helix and quiz elements for autosomal dominant disorders on dark blue background.

Welcome to "What Is Autosomal Dominant Disorder? Take the Quiz!" - a friendly challenge to test your mastery of genetic inheritance. In this interactive genetic disorders quiz, you'll uncover what is autosomal dominant disorder, explore the mechanisms of autosomal dominant inheritance, and review real-world examples of autosomal dominant disorders like Huntington's disease and Marfan syndrome. You'll also compare dominant vs recessive disorders to sharpen your understanding. Curious about other patterns? Dig into multifactorial inheritance disorders for more depth. Ready to level up? Start now - and don't miss our genetic diseases quiz for extra brain-teasers!

What defines an autosomal dominant disorder?
A mutation on the X chromosome
Two mutated alleles on the autosomes are required for disease
Mitochondrial DNA mutation passed from the mother
A single mutated allele on one of the autosomes causes disease
An autosomal dominant disorder is caused when one copy of a mutant allele on an autosome is sufficient to cause the phenotype. Affected individuals inherit one mutated allele from an affected parent or arise from a new mutation. Both males and females are equally at risk and it typically shows vertical transmission in pedigrees. MedlinePlus Genetics
What is the approximate risk that a child will inherit an autosomal dominant disorder when one parent is affected?
25%
100%
50%
75%
Each child of an affected parent has a 50% chance of inheriting the mutant allele because of independent segregation of alleles during gamete formation. This assumes full penetrance and typical Mendelian inheritance. Environmental and modifier genes can slightly alter the phenotypic outcome but not the initial risk. Genetics Home Reference
Which characteristic is typical of autosomal dominant inheritance?
Affected individuals appear in every generation
Only males are affected
Requires two copies of the mutant allele
The trait consistently skips generations
Autosomal dominant traits typically appear in each generation because only one mutant allele is needed for expression. Both males and females are equally likely to be affected. Affected offspring usually have an affected parent, showing vertical transmission. MedlinePlus Genetics
Which of the following is a classic example of an autosomal dominant disorder?
Achondroplasia
Tay - Sachs disease
Cystic fibrosis
Sickle cell anemia
Achondroplasia is the most common form of human dwarfism and is inherited in an autosomal dominant pattern due to mutations in the FGFR3 gene. Affected individuals have one mutant and one normal allele. Most new cases result from de novo mutations in FGFR3. MedlinePlus Genetics
What term describes the phenomenon where some individuals with an autosomal dominant mutation show no clinical symptoms?
Reduced penetrance
Mosaicism
Genetic anticipation
Variable expressivity
Reduced penetrance occurs when individuals carry a disease-causing mutation but do not exhibit any clinical signs of the disorder. This can complicate family histories by making the trait appear to skip generations. Penetrance may be influenced by modifier genes or environmental factors. MedlinePlus Genetics
What describes variable expressivity in autosomal dominant disorders?
Differences in severity among individuals with the same mutation
Mutation occurs at varying rates in different tissues
Allele frequency varies in different populations
Trait is passed only to one sex
Variable expressivity refers to the range of signs and symptoms that can occur in different people with the same genetic condition. Even within the same family, the clinical presentation can be mild in one individual and severe in another. This variability can be due to modifier genes, environment, or stochastic events. MedlinePlus Genetics
Which term refers to earlier onset or increased severity of an autosomal dominant disorder in successive generations?
Genetic anticipation
Pleiotropy
Founder effect
Heterozygote advantage
Genetic anticipation is observed when disease symptoms present at an earlier age or with increased severity in successive generations, commonly seen in trinucleotide repeat disorders like Huntington disease. It is caused by expansion of repeat sequences during gametogenesis. Recognition of anticipation is important for risk assessment in families. MedlinePlus Genetics
A child presents with an autosomal dominant disorder but there is no family history. Which mechanism is most likely?
Compound heterozygosity
De novo mutation
Reduced penetrance
Mosaicism
A de novo mutation arises spontaneously in the egg or sperm or early in embryogenesis, leading to an autosomal dominant disorder in a child with no affected parents. This accounts for many cases of conditions like achondroplasia. Parents are typically not carriers of the mutant allele in their germline. MedlinePlus Genetics
How does germline mosaicism affect recurrence risk counseling in autosomal dominant disorders?
Offspring risk is always zero
Risk may be higher than general population despite unaffected parents
It does not influence risk
It doubles the risk to 100%
Germline mosaicism occurs when some gametes carry a mutation that is absent in somatic cells, so parents appear unaffected yet can transmit the pathogenic variant. This can increase recurrence risk above population levels even if genetic testing of the parents is negative. Accurate counseling must include this possibility when explaining risks. MedlinePlus Genetics
Which mechanism best describes the pathogenesis of Huntington disease?
Toxic gain-of-function from polyglutamine expansion
Haploinsufficiency
Loss-of-function due to gene deletion
Dominant-negative effect
Huntington disease is caused by CAG repeat expansions in the HTT gene, leading to a mutant huntingtin protein that gains toxic functions and forms neuronal aggregates. The toxicity disrupts cellular processes and leads to neurodegeneration. This toxic gain-of-function mechanism distinguishes it from loss-of-function disorders. MedlinePlus Genetics
What is haploinsufficiency in the context of autosomal dominant disorders?
Additional gene copies enhance function
Two copies are required for a mutant phenotype
Mutation only affects males
One functional copy of a gene is insufficient for normal function
Haploinsufficiency occurs when a single normal allele cannot produce enough gene product to maintain normal function, leading to disease in individuals heterozygous for a loss-of-function mutation. It is a common mechanism in autosomal dominant disorders like familial hypercholesterolemia. Recognizing haploinsufficiency helps explain why loss-of-function mutations can act dominantly. Wikipedia
Which pedigree pattern is most indicative of autosomal dominant inheritance?
Only one sex shows the trait
Horizontal pattern confined to siblings only
Vertical transmission with both sexes affected across generations
Trait appears only in grandchildren skipping parents
Autosomal dominant inheritance shows a vertical pedigree pattern, with affected individuals in every generation and roughly equal numbers of affected males and females. Skipped generations are uncommon unless reduced penetrance occurs. This contrasts with autosomal recessive traits that often appear in siblings without prior family history. MedlinePlus Genetics
In segmental neurofibromatosis type 1, what mechanism explains the localized distribution of lesions?
Post-zygotic somatic mosaicism
Germline heterozygosity
Uniparental disomy
Germline mutation
Segmental neurofibromatosis type 1 results from a post-zygotic NF1 gene mutation occurring after fertilization, leading to mosaicism in a subset of cells. This produces lesions restricted to certain body regions rather than the generalized presentation seen in germline mutations. Somatic mosaicism can complicate diagnosis and genetic counseling. Wikipedia
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Study Outcomes

  1. Understand Autosomal Dominant Disorder -

    Explain what is autosomal dominant disorder by defining its genetic basis and how a single mutated allele leads to trait expression.

  2. Differentiate Dominant vs Recessive Disorders -

    Compare autosomal dominant inheritance with recessive inheritance to highlight key differences in transmission and phenotypic presentation.

  3. Identify Examples of Autosomal Dominant Disorders -

    Recognize common genetic conditions that follow autosomal dominant inheritance, such as Huntington's disease and Marfan syndrome.

  4. Apply Mendelian Inheritance Principles -

    Use Punnett squares and basic probability to predict offspring risk in autosomal dominant inheritance scenarios.

  5. Interpret Inheritance Probabilities -

    Calculate the likelihood of passing on a dominant trait to offspring based on parental genotypes.

  6. Reinforce Learning with a Genetic Disorders Quiz -

    Test your comprehension through a scored genetic disorders quiz that challenges your grasp of autosomal dominant inheritance concepts.

Cheat Sheet

  1. Defining the Disorder -

    Understanding what is autosomal dominant disorder starts with recognizing that a single mutated copy on a non-sex chromosome is enough to cause disease. This clear-cut pattern of autosomal dominant inheritance underpins many vibrant discussions in genetics courses and genetic disorders quizzes. Use the mnemonic "One and Done" to recall one mutant allele triggers the trait!

  2. Penetrance vs. Expressivity -

    Even within autosomal dominant inheritance, penetrance measures the percentage of mutation carriers who show any symptoms, while expressivity gauges how severe these symptoms can be. For instance, BRCA1 mutations have high penetrance but variable expressivity in breast cancer risk. Remember "P.E. Variates" as a quick mnemonic to differentiate these concepts!

  3. Examples of Autosomal Dominant Disorders -

    Classic examples of autosomal dominant disorders include Huntington's disease, Marfan syndrome, and familial hypercholesterolemia - all featured in case studies on reputable sites like NIH Genetics Home Reference. Each showcases distinct inheritance patterns and clinical features, making them ideal examples of autosomal dominant disorders for quizzes and classroom discussions. Try listing these examples from memory to ace any genetic disorders quiz!

  4. Pedigree Analysis & Punnett Squares -

    Pedigree charts help trace autosomal dominant inheritance across generations, revealing affected individuals in every generation with a 50% risk per child. A simple Punnett square with an Aa (affected) × aa (unaffected) cross predicts a 1:1 ratio of affected to unaffected offspring. Practicing a few crosses cements your grasp on dominant vs. recessive disorders!

  5. Dominant vs. Recessive Disorders -

    Dominant disorders require only one mutant allele, whereas recessive disorders need both alleles mutated for manifestation - keep the mnemonic "One is Enough, Two is Too" in mind. This comparison is a staple question in any genetic inheritance quiz or study guide. Reinforce your knowledge by contrasting autosomal dominant inheritance with autosomal recessive patterns from trusted genetics textbooks.

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