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Questions and Answers
What type of chromosomal abnormality results from a portion of a chromosome being missing?
What type of chromosomal abnormality results from a portion of a chromosome being missing?
Which chromosomal abnormality is commonly associated with a karyotype of 47, XXY?
Which chromosomal abnormality is commonly associated with a karyotype of 47, XXY?
What chromosomal abnormality is most likely to lead to spontaneous abortion during the first trimester?
What chromosomal abnormality is most likely to lead to spontaneous abortion during the first trimester?
What physical feature is NOT commonly associated with Turner syndrome?
What physical feature is NOT commonly associated with Turner syndrome?
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Which method has the advantage of providing a global strategy for viewing the chromosomal complement but suffers from low resolution?
Which method has the advantage of providing a global strategy for viewing the chromosomal complement but suffers from low resolution?
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What advantage does comparative genomic hybridization offer for genetic analysis?
What advantage does comparative genomic hybridization offer for genetic analysis?
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Which of the following is NOT a disadvantage of the Polymerase Chain Reaction (PCR)?
Which of the following is NOT a disadvantage of the Polymerase Chain Reaction (PCR)?
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Which indication for genetic analysis relates to the mother’s age?
Which indication for genetic analysis relates to the mother’s age?
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What is a limitation of comparative genomic hybridization?
What is a limitation of comparative genomic hybridization?
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What method does RT-PCR use to amplify genetic material?
What method does RT-PCR use to amplify genetic material?
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What is the most common mutation associated with cystic fibrosis?
What is the most common mutation associated with cystic fibrosis?
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Which organ is primarily affected by excessive NaCl excretion in cystic fibrosis?
Which organ is primarily affected by excessive NaCl excretion in cystic fibrosis?
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What is the likelihood of a son being affected if his mother is a carrier of an X-linked recessive disorder?
What is the likelihood of a son being affected if his mother is a carrier of an X-linked recessive disorder?
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Which of the following conditions is NOT classified as an autosomal recessive disease?
Which of the following conditions is NOT classified as an autosomal recessive disease?
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In X-linked recessive inheritance, what can be concluded about the daughters of an affected male?
In X-linked recessive inheritance, what can be concluded about the daughters of an affected male?
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What is a classic symptom of pancreatic involvement in cystic fibrosis?
What is a classic symptom of pancreatic involvement in cystic fibrosis?
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What is the inheritance pattern of almost all X-linked disorders?
What is the inheritance pattern of almost all X-linked disorders?
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Which of the following statements about men and X-linked conditions is correct?
Which of the following statements about men and X-linked conditions is correct?
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What is the inheritance pattern of Fragile X syndrome?
What is the inheritance pattern of Fragile X syndrome?
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What is the commonly observed physical phenotype in males with Fragile X syndrome?
What is the commonly observed physical phenotype in males with Fragile X syndrome?
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Which chromosomal abnormality is associated with Turner syndrome?
Which chromosomal abnormality is associated with Turner syndrome?
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What is the effect of an expansion of trinucleotides in the FMR1 gene?
What is the effect of an expansion of trinucleotides in the FMR1 gene?
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How are mitochondrial disorders typically inherited?
How are mitochondrial disorders typically inherited?
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Which of the following represents an example of aneuploidy?
Which of the following represents an example of aneuploidy?
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Among the following, which disorder is primarily associated with severe bleeding due to issues with clotting factors?
Among the following, which disorder is primarily associated with severe bleeding due to issues with clotting factors?
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What is defined as a multiple of the haploid (n) number of chromosomes?
What is defined as a multiple of the haploid (n) number of chromosomes?
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In autosomal dominant disorders, what is true about the inheritance pattern?
In autosomal dominant disorders, what is true about the inheritance pattern?
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Which of the following disorders is categorized as an autosomal dominant disorder?
Which of the following disorders is categorized as an autosomal dominant disorder?
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What is the likelihood of an offspring being affected by an autosomal dominant disorder if one parent is affected and the other is not?
What is the likelihood of an offspring being affected by an autosomal dominant disorder if one parent is affected and the other is not?
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What characterizes autosomal recessive disorders in terms of allele mutation?
What characterizes autosomal recessive disorders in terms of allele mutation?
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What is a common cause of autosomal recessive disorders?
What is a common cause of autosomal recessive disorders?
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Which of the following statements about Marfan's syndrome is true?
Which of the following statements about Marfan's syndrome is true?
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In the context of cystic fibrosis, what is the genetic inheritance pattern?
In the context of cystic fibrosis, what is the genetic inheritance pattern?
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Study Notes
Transmission Patterns of Single-Gene Disorders
- Follow Mendelian rules, categorized as autosomal dominant, autosomal recessive, or X-linked disorders.
Autosomal Dominant Disorders
- Manifested in heterozygous state, only one mutant allele required for disease expression.
- Typically involves structural proteins; affected individuals can transmit the condition.
- Equal incidence in males and females; 50% probability of offspring being affected.
- Examples include:
- Huntington’s Disease: Neurological disorder.
- Neurofibromatosis: Tumors on nerve tissue.
- Marfan Syndrome: Fibrillin defect leading to aortic dissection.
- Familial Hypercholesterolemia: Elevated cholesterol levels.
Autosomal Recessive Disorders
- Largest category of Mendelian disorders, requiring both alleles to be mutated for phenotype expression.
- Mostly linked to metabolic errors.
- 25% chance offspring will inherit the disorder if both parents are carriers.
- Examples include:
- Cystic Fibrosis: Caused by mutations in CFTR, leading to severe respiratory and digestive issues.
- Phenylketonuria (PKU): Metabolic disorder affecting amino acid breakdown.
- Sickle Cell Disease: Hematopoietic disorder affecting red blood cell shape.
X-Linked Disorders
- Mostly recessive; affect males more due to hemizygosity for the X chromosome.
- Affected males do not pass the condition to their sons, but all daughters become carriers.
- Common disorders include:
- Duchenne Muscular Dystrophy: Progressive muscle degeneration.
- Hemophilia A and B: Blood clotting disorders.
- Fragile X Syndrome: Leading cause of familial intellectual disability, involves CGG repeat expansion.
Mitochondrial Disorders
- Maternal inheritance; diseases are passed down from affected mothers to all children.
- Example: Leber Hereditary Optic Neuropathy.
Chromosomal Abnormalities
- Common in live births (1 in 200) and miscarriages (50% of first-trimester losses).
- Can be numerical (aneuploidy) or structural (deletions, translocations).
- Down Syndrome: Most common aneuploidy caused by Trisomy 21, characterized by mental retardation and physical anomalies.
- Turner Syndrome: Affects females, often resulting from monosomy X, associated with short stature and infertility.
Diagnosis of Genetic Diseases
- Karyotype: Identifies overall chromosome structure but has low resolution.
- Fluorescence In Situ Hybridization (FISH): High resolution, used for specific abnormalities.
- Comparative Genomic Hybridization: Identifies chromosomal differences, may miss subtle changes.
- Molecular Diagnosis: Utilizes techniques like PCR to detect nucleotide-level mutations.
Indications for Genetic Analysis
- Prenatal Analysis: Age of mother, known carrier status, previous chromosomal anomalies.
- Postnatal Analysis: Unexplained mental retardation, infertility, and multiple congenital anomalies.
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Description
Test your knowledge on the transmission patterns of single-gene disorders, with a focus on Mendelian inheritance rules. This quiz covers autosomal dominant, autosomal recessive, and X-linked disorders, ensuring a comprehensive understanding of genetic conditions.