34 Questions
Which type of inheritance is associated with Marfan syndrome?
Autosomal dominant
What is the main cause of marfan syndrome?
Loss of fibrillin-1
Which enzyme is deficient in Gaucher disease?
Glucocerebrosidase
What is the prevalence of Gaucher disease?
Between 1 in 20,000 and 1 in 40,000 live births
Which type of disorder is Marfan syndrome?
Connective tissue disorder
What is the main cause of mortality and morbidity in Marfan syndrome?
Aneurysms and valvular defects
Which chromosome is associated with Marfan syndrome?
Chromosome 15
What is the defect in Gaucher disease?
Defect in the gene for glucocerebrosidase
What is the most common type of Gaucher disease?
Type I – involves organs outside the central nervous system
What is the inheritance pattern of X-linked disorders?
Mostly recessive
In X-linked recessive inheritance, the trait is never passed from father to son because:
The trait is only carried on the X chromosome, which sons inherit from their mother.
A male with a mutant allele on his single X chromosome is considered:
Hemizygous for the allele.
What is the risk of autosomal recessive disorders manifesting if there is consanguinity?
The risk increases due to the potential for homozygosity of the alleles.
What is the typical chance of transmission in autosomal dominant inheritance?
50%
Why do heterozygous females usually not express the full phenotypic change in X-linked disorders?
Due to the presence of a paired normal allele.
In X-linked recessive inheritance, who can transmit the disorder to affected males?
Healthy heterozygous female carriers.
What is the term for the pattern of inheritance where only males appear affected and the trait is never passed from father to son?
X-linked recessive inheritance.
What is the term for the condition where there is a loss of function of a coagulation factor necessary for clotting?
Hemophilia A.
What category of diseases can affect both males and females throughout many generations?
Autosomal dominant pedigree.
What type of mutation can lead to a frameshift mutation?
Insertion of a single nucleotide
Which type of point mutation results in a significant change in protein function?
Nonconservative missense mutation
What mutation can lead to premature ending of translation and a truncated protein?
Nonsense mutation
Which type of mutation involves interchanges of purines or pyrimidines, and can result in changes at one or very few nucleotides?
Transitions
What type of mutation can lead to a total loss of function of the protein?
Frameshift mutation
Which mutation results in the most common mutation in cystic fibrosis?
Non-frameshifting indels
What type of mutation involves interchanges of purine for pyrimidine bases?
Transversions
Which mutation is protective against malaria?
Sickle-cell trait
Which type of missense mutation leads to significant changes in function?
Nonconservative missense mutation
What determines the likelihood and intensity of expression in autosomal dominant disorders?
Penetrance and expressivity
Which type of Mendelian disorder is manifested in the heterozygous or homozygous state and usually has at least one affected parent?
Autosomal dominant
What is the term for disorders caused by mutations in single genes?
Mendelian disorders
All sex linked disorders are _____
Gaucher disease is an example of_____
Autosomal recessive
Hemophilia is an example of ______
X-linked recessive
Study Notes
Genetic Mutations and Disorders Overview
- Gene mutations can be point mutations, frameshift mutations, or trinucleotide-repeat mutations
- Lifetime frequency of genetic disorders is estimated at 670/1000, with 50% of miscarriages having chromosomal abnormalities
- Point mutations can be substitutions, insertions, or deletions, with transitions and transversions being types of substitutions
- Insertions or deletions of nucleotides can lead to frameshift mutations, resulting in the loss of protein function
- Silent or conservative missense point mutations cause little or no change in function, while nonconservative missense mutations lead to significant changes in function
- Some mutations, like those causing sickle cell anemia, have protective effects, such as resistance to malaria
- Mendelian disorders can be autosomal dominant, autosomal recessive, or X-linked, and are caused by mutations in single genes
- Autosomal dominant disorders are manifested in the heterozygous or homozygous state and usually have at least one affected parent
- Penetrance and expressivity determine the likelihood and intensity of the disorder's expression in autosomal dominant disorders
- Most mutations in autosomal dominant disorders lead to a protein with reduced function or decreased production
- Disorders due to insufficient enzyme production tend to be recessive
- The molecular mechanisms behind the variability in the expression of autosomal dominant disorders are not fully understood
Test your knowledge of genetic disorders with this quiz covering gene mutations, complex multigenic disorders, and chromosomal disorders. Learn about frameshift mutations, point mutations, trinucleotide-repeat mutations, and more. Understand how genotype commonly contributes to disease and the estimated frequency of genetic disorders.
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