Lecture 3 Flashcards
True or False: Two different genotypes may have the same phenotype
True (e.g dominant homozygote and heterozygote for CF have same “normal” phenotype - AA vs. Aa)
___ risk: no affected child yet born
___ risk: have one or more affect kids
Occurrence Risk
Recurrence Risk
What is an example in which the same genotype may productive different phenotypes in different environments?
PKU
- If diet that is low in phenylalanine is initiated within 1 month of birth, individual with genotype does not have phenotype of intellectual disability
True or False: First degree relatives are those related at the parent offspring or sibling level while Second degree relatives are removed by one additional generation step (e.g grandparents, grandkids)
True
___-degree relatives include first cousins and great grandchildren
Third-degree
An arrow usually denotes the ___ or first individual diagnosed in the pedigree or the person from whom the pedigree is drawn
proband
Mutations in __ gene results in PKU, which is a disease in which person is unable to metabolized phenylalanine
PAH
True or False: Environment can include genetic environment, as well as external environment
True
What are four features of autosomal dominance?
1) Vertical transmission
2) No skipped generations
3) Equal proportion of females and males
4) Father to son transmission possible
Postaxial polydactylyl is an example of an ____ ___ trait
A. Autosomal recessive
B. Autosomal dominant
C. X-linked
B. Autosomal dominant
True or False: In autosomal dominant traits, males and females are affected with equal frequency and male to male transmission of trait can occur
True
True or False: In autosomal dominant traits, unaffected individuals have affected offspring
False - in autosomal dominant traits, unaffected individuals do NOT have affected offspring
True or False: In autosomal dominant inheritance, the heterozygous state is MORE severe than the homozygous state
False - heterozygous state is LESS severe than homozygous
What type of mutations are common in autosomal dominant traits?
Spontaneous mutations
First degree relatives (parents and kids or parents and sibling) share ___% of DNA
Second degree relatives (grandkids and grandparents) share __% of DNA
Third degree relatives (first cousins) share __% of DNA
50%
25%
12.5%
What’s the difference between a first cousin once removed and a second cousin?
First cousin once removed
- First cousin of your parent
- Child of first cousin
Second cousin:
- Children of first cousins are second cousins to each other
True or False: Children of second cousins are third cousins to each other
True
When inheritance of a single gene results in a phenotype, this is known as ____ inheritance
Mendelian
True or False: Most affected individuals are heterozygous and have one affected heterozygous (Aa) parent and one unaffected homozygous (aa) parent
True
Which four disorders are inherited as autosomal dominant traits? Which genes are associated?
1) Huntington’s Disease - HTT gene
2) Marfan Syndrome - FBN1 gene
3) Neurofibromatosis Type 1 - NF1 gene
4) Retinoblastoma - Rb gene
On average, ___ of the offspring of affect individuals are affected
A. 1/4
B. 1/2
C. 100%
1/2
True or False: In autosomal dominant traits, genetically unaffected persons do not have affected offspring
True
True or False: In autosomal dominant traits, the trait rarely shows variation in expression
False - in autosomal dominant traits, the trait FREQUENTLY shows variation in expression
In autosomal dominant traits, basic defects tend to involve _____ _____
structural protein
What are two diseases in which homozygous state is more severe?
1) Factor V Leiden Mutation
2) Prothrombin Mutation
- inherited thombophilia
Who is at a greater risk for a DVT?
A. Heterozygote with Factor V Leiden mutation
B. Homozygous with Factor V Leiden mutation
B. Homozygous with Factor V Leiden mutation
Mutation in the ___ gene can lead to Factor V Leiden mutation, which follows a autosomal dominant inheritance and is more severe in homozygotes
A. CY11B2
B. F5
C. F2
B. F5
True or False: A G20210A mutation in the F2 gene can give rise to Factor V Leiden mutation
False - A G20210A mutation in the F2 gene can give rise to the Prothrombin mutation
True or False: Factor V Leiden mutation is more severe in homozygotes while Prothrombin mutation is more severe in heterozygotes
False - both Factor V Leiden and Prothrombin mutation are MORE severe in homozygotes
True or False: For both Factor V Leiden mutation and Prothrombin mutation, there is hormonal influence on disease expression
True
True or False: In sex-linked disorders, one sex may be more apt to express disease phenotype
True
True or False: Male and females are not equally likely to inherit BRCA mutations. However, males are still very likely to develop breast cancer.
False - male and females ARE equally likely to inherit BRCA mutations and males are UNLIKELY to develop breast cancer
Who can pass the mutant BRCA allele to daughter, who then develop breast cancer at a young age?
A. Unaffected father
B. Unaffected mother
C. Affected mother
D. Affected father
A. Unaffected father
True or False: A person can appear to have no family history of breast cancer if the allele has been passed from male to male in previous generations
True
What are four features of autosomal recessive inheritance?
1) Horizontal transmission
2) Skipped generations
3) Equal proportions of female and males
4) Father to son transmission possible
True or False: Persons affected with autosomal recessive diseases ALWAYS have two carrier (heterozygous) parents
False - Persons affected with autosomal recessive diseases ALMOST ALWAYS have two carrier (heterozygous) parents
True or False: BRCA1 and BRCA2 genetic mutations are examples of a sex-limited disorder
True
Tyrosine-negative albinism is an example of which type of inheritance?
A. Autosomal Dominant
B. Sex-limited
C. Sex-linked
D. Autosomal Recessive
D. Autosomal Recessive
Provide 6 examples of autosomal recessive disorders:
(hint: Gun Shot Wound, THC)
G - Gaucher Disease (N370S)
S - Sickle Cell (HbB)
W - Wilson’s Disease (ATP7B)
Tay Sachs (HEXA)
Hereditary Hemochromatosis (HFE)
CF (CFTR)
True or False: Almost all persons with hereditary hemochromatosis have two carrier parents
True - since hereditary hemochromatosis is a autosomal recessive condition
True or False: A person with an autosomal recessive disorder may have two of the SAME mutant alleles or two DIFFERENT mutant alleles (compound heterozygote)
True
True or False: Many people with hemochromatosis have two different mutations in HFE
False - many people with CF have two DIFFERENT mutations in CFTR
Many people with this autosomal recessive disorder are compound heterozygotes:
A. Wilson Disease
B. Sickle Cell Disease
C. CF
D. Tay Sachs Disease
E. Gaucher Disease
F. Hereditary Hemochromatosis
F. Hereditary Hemochromatosis
____, an iron storage disorder, is both autosomal recessive and sex limited
A. Wilson Disease
B. Sickle Cell Disease
C. CF
D. Tay Sachs Disease
E. Gaucher Disease
F. Hereditary Hemochromatosis
F. Hereditary Hemochromatosis
Why does iron not build up in women with hemochromatosis to the same degree as men?
Menses
True or False: Women with hemochromatosis present at older ages than men
True
What is the prevalence of affect children in autosomal recessive inheritance?
A. 100%
B. 75%
C. 50%
D. 25%
D. 25%
True or False: In autosomal recessive inheritance, disease phenotype is not seen in every generation and males and females are affected with equal frequency
True
A high prevalence of a rare autosomal recessive disease suggests _____, which is mating of closely related individuals (usually first cousins)
consanguinity
