Questions and Answers
In nonallelic heterogeneity, mutations at two or more distinct loci on different chromosomes can produce:
Identical or closely similar phenotypes
Which of the following is an example of genetically heterogeneous disease mentioned in the text?
Alzheimer disease
What type of inheritance pattern is most commonly associated with over 7000 known Mendelian phenotypes?
Autosomal dominant inheritance
In classical autosomal dominant inheritance, affected individuals are usually heterozygotes for:
Signup and view all the answers
What is the chance that a gamete from an individual with an autosomal dominant disorder will carry the mutant allele?
Signup and view all the answers
What is the definition of allelic heterogeneity?
Signup and view all the answers
How does heterogeneity manifest at the locus level?
Signup and view all the answers
What is the main function of the CFTR protein?
Signup and view all the answers
How does allelic heterogeneity contribute to clinical variation?
Signup and view all the answers
Which statement best describes nonallelic heterogeneity?
Signup and view all the answers
What can modify the expression of an abnormal genotype?
Signup and view all the answers
Which term describes a situation where the manifestation of a phenotype differs in people who have the same genotype?
Signup and view all the answers
In patients with autosomal dominant disorders with variable expressivity, what may differ among individuals?
Signup and view all the answers
Which gene is associated with cystic fibrosis transmembrane conductance regulator (CFTR)?
Signup and view all the answers
How do modifier genes affect gene expression?
Signup and view all the answers
What is the term used to describe a person with different alleles, one dominant and one recessive?
Signup and view all the answers
According to the Law of Segregation, what happens at meiosis?
Signup and view all the answers
What is the term for an individual's outward appearance?
Signup and view all the answers
In offspring from parents who are both heterozygotes, what proportion will be homozygous for the recessive gene?
Signup and view all the answers
'Independent Assortment' refers to what in genetic terms?
Signup and view all the answers
What term is used to describe a genetic disorder that can be caused by different genetic mechanisms but leads to the same or similar phenotype?
Signup and view all the answers
Which of the following genetic concepts refers to the occurrence of an autosomal allele more frequently in one sex than the other?
Signup and view all the answers
In what condition is there enhanced absorption of dietary iron leading to iron overload and serious pathological consequences?
Signup and view all the answers
Which genetic disorder is more common in males and involves the deposition of uric acid crystals in a joint, leading to sudden inflammation?
Signup and view all the answers
When a genetic disorder that seems like a single entity is found to have multiple phenotypes determined by different genotypes, it is an example of:
Signup and view all the answers
In the context of genetic heterogeneity, what term describes the situation when a single disorder can be caused by different mutations in the same gene?
Signup and view all the answers
Which term refers to the situation where mutations at different loci on different chromosomes can produce the same disorder?
Signup and view all the answers
Cystic Fibrosis is caused by mutations in which gene?
Signup and view all the answers
What best describes a situation where individuals with the same disease-causing mutation show a wide range of clinical presentations?
Signup and view all the answers
Which term is used to describe a single gene disorder that can manifest itself in different ways in different individuals?
Signup and view all the answers
What term is used to describe a single-gene disorder that is determined by a specific allele at a single locus on a chromosome pair?
Signup and view all the answers
In pedigree construction, what is the first step to establish the pattern of transmission of single-gene disorders in families?
Signup and view all the answers
Which factor determines the patterns of single-gene disorders in pedigrees?
Signup and view all the answers
In Mendelian inheritance, how is dominance defined in terms of phenotypes?
Signup and view all the answers
What type of inheritance pattern occurs when a phenotype is expressed only when both chromosomes carry a mutant allele?
Signup and view all the answers
Which term describes a situation where two alleles are termed codominant because each can be detected even in the presence of the other?
Signup and view all the answers
In Mendelian inheritance, when is a phenotype considered dominant?
Signup and view all the answers
What is the term for the phenomenon where individuals with the same genotype show different clinical presentations?
Signup and view all the answers
Which term describes the probability that a person carrying a disease-causing mutation will actually develop the disease?
Signup and view all the answers
In autosomal dominant disorders with variable expressivity, what may differ among affected individuals?
Signup and view all the answers
What determines whether a phenotype is autosomal dominant or autosomal recessive?
Signup and view all the answers
In autosomal dominant disorders, what term is used to describe the situation where some individuals do not express the phenotype despite inheriting the mutant allele?
Signup and view all the answers
Which term describes the phenomenon where individuals with the same autosomal dominant disorder exhibit a range of different clinical symptoms and severity?
Signup and view all the answers
Individuals with Marfan syndrome often exhibit cardiovascular anomalies like mitral valve prolapse and aortic regurgitation. What type of inheritance pattern is associated with Marfan syndrome?
Signup and view all the answers
Neurofibromatosis is an example of an autosomal dominant disorder. Which term describes the situation where different individuals with neurofibromatosis may have varying numbers and sizes of neurofibromas?
Signup and view all the answers
What term is used to describe a genetic situation where two different alleles contribute to the phenotype, both of which are fully expressed?
Signup and view all the answers
In classical autosomal dominant inheritance, what is the probability that a gamete from an individual with the disorder will carry the normal allele?
Signup and view all the answers
What is the term for the situation where individuals with an autosomal dominant disorder exhibit different symptoms despite having the same genotype?
Signup and view all the answers
Which of the following genetic concepts refers to the likelihood that an individual with a disease-causing mutation will actually show symptoms of the disorder?
Signup and view all the answers
For autosomal dominant disorders with incomplete penetrance, what do unaffected individuals in a pedigree lack?
Signup and view all the answers
Which phenomenon is described when multiple distinct mutations on different chromosomes can lead to the same or similar phenotype?
Signup and view all the answers
Which hallmark of autosomal dominant inheritance states that every affected individual has an affected biological parent?
Signup and view all the answers
Which statement is true about autosomal dominant inheritance?
Signup and view all the answers
In autosomal dominant disorders, which factor contributes to the phenotypic variability among affected individuals?
Signup and view all the answers
In X-linked dominant inheritance, what distinguishes affected males' offspring?
Signup and view all the answers
Which statement is true about X-linked recessive inherited disorders?
Signup and view all the answers
What distinguishes an autosomal dominant inheritance pattern from an X-linked dominant one?
Signup and view all the answers
In X-linked dominant disorders, if any daughter is unaffected or any son is affected, what does this indicate?
Signup and view all the answers
What is a distinguishing feature of an X-linked dominant pedigree?
Signup and view all the answers
In the context of genetic disorders, what term is used to describe the penetrance in Huntington disease?
Signup and view all the answers
Which of the following disorders is characterized by choreic movements, progressive dementia, and typically has onset in the 4-5th decade?
Signup and view all the answers
What genetic disorder exhibits age-dependent penetrance and is known for showing delayed penetrance?
Signup and view all the answers
Pleiotropy refers to a genetic phenomenon where a single gene can cause multiple distinct phenotypic effects. Which disorder exemplifies this concept from the text?
Signup and view all the answers
Which genetic disorder is most closely associated with abnormalities of skin pigmentation, neurofibromas of the peripheral nerves, short stature, skeletal abnormalities, and other symptoms?
Signup and view all the answers
Why should an individual with an autosomal dominant disease always be considered as a heterozygote?
Signup and view all the answers
What is the probability that two affected heterozygotes with an autosomal dominant disease will have a homozygous affected offspring?
Signup and view all the answers
Why is the pattern of autosomal dominant inheritance considered one of the easiest to recognize in a pedigree?
Signup and view all the answers
What is the main reason for considering each pregnancy as an independent event in terms of inheritance?
Signup and view all the answers
Why do individuals with autosomal dominant diseases exhibit variable expressivity?
Signup and view all the answers
Why are individuals with autosomal dominant disorders more commonly considered as heterozygotes?
Signup and view all the answers
Why should each pregnancy within a family be treated as an independent event in terms of genetic inheritance?
Signup and view all the answers