Week 2 Flashcards
When calculating the frequency of alleles, the number (n) of homozygous (AA) or heterozygous (Aa) samples must be doubled before dividing by 2N?
Homozygous (AA)
In a dominant gene disease, which allele is pathogenic, d or D?
D
What is the typical recurrence risk for an Autosomal Dominant disease?
50%
In the Hardy-Weinberg Law formula: p2 + 2pq + q2 = 1 , what does the p2 represent in terms of alleles?
Frequency of AA
If some people with a mutation of a gene do not develop the features of the disorder, the condition is said to have:
A reduced penetrance
Tay Sachs Disease:
Autosomal Dominant, or Recessive?
Autosomal Recessive
Traits occuring in only one sex due to anatomical differences are classified as:
Sex-limited Traits,
or
Sex-Influenced Traits?
Sex-Limited Traits
Sickle Cell Anaemia:
Autosomal Dominant, or Recessive?
Autosomal Recessive
A disorder affecting chromosome 11 causes upregulation of growth factor, is this disease:
Beckwith-Weidemann Syndrome
or
Silver-Russel Syndrome?
Beckwith-Weidemann Syndrome
What is the function of Xist RNA?
Inactivation of X Chromosomes
Why do females display a lower severity of symptoms in Fragile X Syndrome than males?
Females have two copies of the X chromosome, one may be a normal copy
(Females are mosaic)
“Common in Ashkenazi Jews and French Canadian peoples.”
Is this a feature of Sickle Cell anaemia, or Tay Sachs disease?
Tay Sachs Disease
What is the purpose of maintenance methylation?
methylating newly synthesised strands of DNA
25% of cases of Prader-Willi syndrome are caused by uniparental disomy of chromosome 15 - what does this mean?
The child inherits both copies of Chromosome 15 from the same parent
(Maternal in this case)
The Angelman Syndrome gene on chromosome 15 is active, or inactive in paternal chromosomes?
Inactive
Why will uniparental disomy of chromosome 15 cause either Prader-Willi or Angelman Syndrome?
Active and Inactive PWS and AS regions are sex-dependant
(Maternal or Paternal)
What does Wild Type refer to in protein synthesis?
Proteins produced by healthy genes before any mutation
Chronic Myelogenous Leukaemia results from translocation of most of chromosome 22 on to the long arm of chromosome 9 in haematopoetic stem cells, what is this new hybrid chromosome known as?
The Philadelphia Chromosome
Two non-homologous acrocentric chromosomes loose their short arms (P), and the residual long arms (Q) fuse to form one long chromosome - what is this phenomenon refererred to as?
Robertsonian Translocation
In the Hardy-Weinberg Law formula: p2 + 2pq + q2 = 1 , what does the q2 represent in terms of alleles?
Frequency of aa
The probability that the child of a patient may inherit a particular disease is known as:
Recurrence Risk
Females are considered genetic mosaics with regard to X-Linked genetic traits - what does this mean?
She will express X-linked alleles from both her mother and her father
What is Pleitropy?
single genes having more than one discernible effect on the body
A mutation in a trinucleotide results in the replacement of Leucine with Proline - is this a nonsense or a missense mutation?
Missense mutation
The Prader-Willi gene on chromosome 15 is active, or inactive in maternal chromosomes?
Inactive
The probability of a child having a genetically inherited disease is proportional to the number of siblings they have.
True
or
False?
False.
With relation to chromosome 15, by what three mechanisms will a patient develop either Prader-Willi Syndrome or Angelman Syndrome?
Uniparental disomy
Defective imprinting
Deletion
What are the three forms of Tay-Sachs disease?
Infantile
Juvenile
Adult/Late
X linked dominant diseases passed down from the mother are seen in boys, girls, or both?
Both
A law states* that genotype and allele frequencies will always remain constant from generation to generation - what is this law?
*provided certain criteria are met
Hardy-Weinberg Law
Swyer Syndrome results from an error in the SRY / SOX9 crossover process, does this result in an XX Male, or an XY Female?
XY Female
Also Known as XY Gonadal Dysgenesis
In the Hardy-Weinberg Law formula: p2 + 2pq + q2 = 1 , what does the 2pq represent in terms of alleles?
Frequency of the Aa combination
What is the phenomenon that describes defective genes in different chromosomes causing the same disease?
Locus Heterogeneity
What is the name of the deactivated X chromosomes in the cells of women?
Barr bodies
Genetic conditions such as Marfan’s Syndrome with a spectrum of mild to severe features is conisdered to have:
Variable Expressivity
A mutation in a trinucleotide encoding the translation of alanine results in no change to the amino acid sequence, was this a misense or a silent mutation?
Silent Mutation
A male inheriting an X-Linked dominant disease would have gained the allele from the mother or the father?
Mother
What is the typical recurrence risk of an autosomal dominant disease?
50%
What aspect of pedigree should be considered when a rare recessive disease is discovered?
Cosanguinity
Is Male Pattern Baldness a Sex-Limited trait, or a Sex-Influenced trait?
Sex-Influenced Trait
Myotonic Dystrophy is an autosomal dominant, or recessive disease?
Autosomal Dominant
is X-Linked Dominant disease transmission possible between fathers and sons?
No
What is the typical recurrence risk for an Autosomal Recessive disease?
25%
In X-Linked Recessive diseases, why is maternal transmission of disease always expressed in sons?
Males do not have a compensatory allele for the affected X-Chromosome gene
during the second stage of gene silencing, Histone Deacetylase (HDAC) binds to both:
MeCP and DNA
Albinism:
Autosomal dominant, or recessive?
Autosomal Recessive
Father to son transmission of genetic disease is an attribute of Autosomal Dominant, or Autosomal Recessive?
Autosomal Dominant
De La Chapelle Syndrome results from an error in the SRY / SOX9 crossover process - Does this result in an XX Male, or an XY Female?
XX Male
Methylation upregulates or downregulates gene expression?
downregulates
is Methylcytosine-binding protein (MeCP) the first or second molecule used in gene silencing?
First
Anticipation of genetic disease (Progresive worsening between generations) is caused by what?
Trinucleotide Repeat Expansion mutation
Robertsonian Translocation occurs between two Homologous or Non-Homologous pairs of chromosomes?
Non-homologous
Both alleles affecting the phenotype are a feature of what type of inheritance?
Codominant Inheritance
A new gene formed at the interface between two translocated chromosome is known as:
An Oncogene
how many generations are required to be examined to qualify a ‘complete’ history, regarding genetic disease?
Three
What do geneticists mean by anticipation?
Severity of the disease and earliness of onset increases as the disorder is passed from one generation to the next
What is the most important factor in calculating recurrence risk?
How the disease is inherited
What is the most straightforward method of epigenetic control?
DNA Methylation
The Angelman Syndrome gene on chromosome 15 is active, or inactive in maternal chromosomes?
Active
Is mitochondrial inheritance maternal, or paternal?
Maternal
The Prader-Willi gene on chromosome 15 is active, or inactive in paternal chromosomes?
Active
Cri-du-chat Syndrome is a resut of a deletion or a translocation of chromosome 5?
Deleted
What is the typical recurrence risk of an autosomal recessive disease?
25%
What does Haploinsufficient mean?
Affected genes do not produce enough proteins to fulfil their designated function
During methylation, which enzyme adds the first methyl group?
de novo methylase
or
Maintenance methylase
de novo methylase
How many of the parents must be carriers of the defective gene in order for one of their offspring to express an autosomal recessive disease?
Both
Familial Isolated Growth Hormone Deficiency (IGHD) is an example of complex genetic transmission, why?
There can be both recessive and dominant IGHD
What is the purpose of the methylated CG-Islands in DNA methylation?
Interfering with DNA transcriptase activity
Chromosomes of what morphology may be subject to Robertsonian Translocation?
Acrocentric
The process of forming Barr Bodies with Xist RNA is known as:
Lyonisation
Robertsonian Translocation occurs during:
Gametogenesis
or
Embryonic Cell Division?
Gametogenesis
Fragile X Syndrome is typically more severe in males, or females?
Males
A disorder affecting chromosome 11 causes downregulation of growth factor, is this disease:
Beckwith-Weidemann Syndrome
or
Silver-Russel Syndrome?
Silver-Russel Syndrome
“Common in Africans, African Americans and Mediterranian peoples.”
Is this a feature of Sickle Cell anaemia, or Tay Sachs disease?
Sickle Cell anaemia
In a recessive gene disease, which allele is pathogenic, d or D?
d
What does Haplosufficient mean?
Accounting for any mutation, there are sufficient proteins produced to maintain homeostatic function
During the first stage of gene silencing, what molecule is attracted to the methylated CG-Islands?
Methylcytosine-binding protein (MeCP)
Where is the site of original de-novo mutation in Germline Mosaicism?
The embryo
De novo methylase adds methyl (CH3) groups to what locations on the DNA molecule?
CG Islands
What are the two forms of Huntington’s Disease?
Adult Onset
Juvenile Onset
