30 Questions
Which of the following is a key clinical feature of Fragile X syndrome?
Triple repeats in the FMR1 gene
What is the biologic mechanism responsible for genomic imprinting?
DNA methylation
Which disorder is explained by genomic imprinting?
Prader-Willi syndrome
How many mechanisms result in Prader-Willi syndrome?
2
What is the conceptual basis of analyzing genetic and environmental interaction in the causation of disease?
Multifactorial inheritance
Which of the following statements about mitochondrial inheritance is true?
Mitochondrial diseases can only be inherited from the mother
What is the main reason for the high mutation rate of mtDNA compared to nuclear DNA?
Mitochondria lack DNA repair mechanisms
Why is there variability in phenotype with mitochondrial disorders?
Variable expression of the same mutation
Which organs are most often affected by mitochondrial diseases?
Brain and muscles
What is the main characteristic of germline mosaicism?
Presence of different cell lines in the germline
Which of the following is true about the incidence of pyloric stenosis in infants?
All of the above
What is the recurrence risk for congenital pyloric stenosis in male probands from London?
12.5%
What is the incidence of infantile autism in third-degree relatives?
0.3%
What is the heritability (h2) of alcoholism?
0.44
What is the heritability (h2) of height?
0.51
Which of the following is an example of a non-Mendelian inheritance pattern?
All of the above
What is the main difference between Mendelian and multifactorial inheritance?
Mendelian inheritance is determined solely by genetic factors, while multifactorial inheritance is determined by genetic and environmental factors
Which of the following is an example of a quantitative complex phenotype of a multifactorial disease?
Height
What is the concept of heritability based on?
The degree of similarity between relatives with respect to genetic traits
What is the threshold model of multifactorial inheritance?
Disease manifests when the liability exceeds a hypothetical threshold
Which of the following is true about anticipation in Mendelian disorders?
Anticipation is explained by trinucleotide repeat expansion in offspring
Which of the following trinucleotide repeat diseases is characterized by a CAG repeat in the protein coding region?
Huntington Disease
What is the threshold number of CGG repeats in the Fragile X gene (FMR1) that is considered abnormal and associated with Fragile X syndrome?
More than 200 repeats
What is the mechanism of loss of gene expression in Prader-Willi Syndrome and Angelman Syndrome?
Deletion
Which of the following is true about X chromosome inactivation?
X chromosome inactivation is influenced by stochastic variation
Which of the following is an example of a triplet repeat disorder?
Fragile X
What is the normal range of trinucleotide repeats in Fragile X syndrome?
5-34 repeats
Which of the following disorders is caused by genomic imprinting?
Prader-Willi syndrome
What is the relationship between skewed X inactivation and human disease?
Skewed X inactivation can lead to disease manifestation in females carrying X-linked mutations.
What is the difference between homoplasmy and heteroplasmy in mitochondrial inheritance?
Homoplasmy refers to the presence of a single type of mitochondrial DNA in an individual, while heteroplasmy refers to the presence of multiple types of mitochondrial DNA.
Test your knowledge on mitochondrial inheritance and the transmission of genes through pedigrees. Explore the unique features of mitochondrial DNA and its association with energy production.
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