Genetics (Integration) Rapid Fire Genetics Flashcards by Junxian Ng

raised blood CK level

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X-inactivation

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False

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Spontaneous

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Absent

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Genetic drift

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No. Switch to safer drug

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False

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DNA

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**Younger than
Familial clustering of tumours (both)

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Mother is a DMD carrier

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There are no non-genetic factors at play

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Have genetic factors

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False

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XLR

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False

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False

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Variable expression

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D. Logic question tbh.

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Inherited from the father

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False

Diagnosis, prognosis, management, recurrance etc etc

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Environmental

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Variable Expression

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Drift or flow

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Nuclear.

Keyword is MOST

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2, ma and pa

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False

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Phenotype or protein

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All

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Genetic flow

Just rmb genetic flow = migration

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False

Where got population level mutation so fast one…

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Gene-environment

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False

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False

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AD or mitochondrial

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Variable expression

Ngl…the answer is always variable expression???

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Don’t travel la lame

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Environmental

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Yes

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Yes

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Selection

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LDL

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25%

Non-dysjunction

(VVVVVV IMPT)

Name 5 AD disorders “Familiar Families Amuse Nerdy Officers”
[…]

Name 5 AR disorders “Beta Cats Pheel Severely Sick”
[…]

Name 4 XLR disorders “Redgreen Girls Destroy Hamsters”
[…]

(VVVVVV IMPT)

Name 5 AD disorders “Familiar Families Amuse Nerdy Officers”
FH
FAP
Achondroplasia
NF1
OI

Name 5 AR disorders “Beta Cats Pheel Severely Sick”
Beta-thalessemia
Cystic Fibrosis
Phenylketonuria
SCID
Sickle cell anemia

Name 4 XLR disorders “Redgreen Girls Destroy Hamsters”
Red-Green colour blindness
G6PD deficiency
DMD
Haemophilia A

Just die die memorize cuz questions assume u know the inheritance pattern. These are important for clinicals as well.

FH = Familial Hypercholesterolemia
FAP = Familial Adenomatous Polyposis coli
NF1 = NeuroFibromatosis type 1
OI = Osteogenesis Imperfecta

SCID = Severe Combined ImmunoDeficiency

DMD = Duchenne Muscular Dystrophy

23 year old male with paternal grandfather with G6PD deficiency is suitable for genetic counselling. T/F?

[…]

False

G6PD deficiency is XLR. Grandfather would have given y to father. father also give y to this patient. So, not indicated for genetic counselling

4 types of phenomenas that can result from a blocked pathway

[…]
[…]
[…]
[…]

4 types of phenomenas that can result from a blocked pathway

Accumulation of a substrate
Accumulation of another substrate as a result of shunting
Lack of product
4.* Secondary metabolic phenomenon*

A child inherits all his/her mitochondrial DNA from his/her mother. T/F?

A substitution is the most common mutation that occurs in DNA. T/F?

A substitution is the most common mutation that occurs in DNA. T/F?
T

All cells that descend from that cell will have the same inactive X and same active X. T/F?

All cells that descend from that cell will have the same inactive X and same active X. T/F?
T

All genes on the X-chromosome are subjected to X-inactivation T/F?

All genes on the X-chromosome are subjected to X-inactivation T/F?
F

All the mitochondrial DNA are identical T/F?

All the mitochondrial DNA are identical T/F?
F

Homoplasmy: All the mitochondrial DNA are identical (eg. All normal or all mutant)
Heteroplasmy: More than 1 type of mitochondrial DNA is present (e.g. mixture of normal variant and pathogenic variant)

Carrier frequency in SG for B thalassemia major is […]%

Carrier frequency in SG for B thalassemia major is 3%

Children with down syndrome have increased risk of […] problems

Children with down syndrome have increased risk of thyroid problems

Common signs of Inborn Errors of Metabolism

Common signs of Inborn Errors of Metabolism
Hypoglycemia
Acidosis
Encephalopathy (Chronic/acute), Mental retardation, Regression
Sudden death
Movement disorder, Weakness
Liver failure
Heart failure
Dysmorphic
Failure to thrive
Very sick even though this is just a minor illness

More of failures rather than malformations

Common teratogenic drugs and toxins

Common teratogenic drugs and toxins
Alcohol - any exposure cause CNS and developmental issues
Thalidomide - first trimester exposure limb deformities
Anticonvulsants: Valproate and Carbamazepine - neural tube defects. Avoid if possible. otherwise folate supplementation prior to conception reduce the risks
Cytotoxics: increased risk for fetal death, growth retardation and malformation
Androgenic hormones: Virilization of the genitalia in a female fetus
Lithium: Epstein’s anomaly of the heart
Warfarin: increased risk of brain, skeletal and growth abnormalities
Isotretinoin and etretinate - increased risk for brain, face, cardiac abnormalities
i
ACE Inhibitors - Oligohydramnios, anuria, renal failure, hypotension, lung issues, fetal growth issues, miscarriage or perinatal death

Compare the differences between Discrete/qualititative and Quantitative Complex disease

Complex Diseases are aka multifactorial diseases. T/F

Complex Diseases are aka multifactorial diseases. T/F
T

Types of disease Population affected
Single gene disorders 2%
Chromosomal disorders 0.7% newborns
Mitochondrial diseases rare
Multifactorial diseases >60%

Define dynamic mutations, what does it result in?

Define dynamic mutations, what does it result in?
Mutations that are are unstable when passed from one generation to another generation

Anticipation

Define Genomic Imprinting

Define Genomic Imprinting
Defined as a phenomenon where the expression of a gene is dependent on the parent of origin

Define single gene disorder, list the different types.

Define single gene disorder, list the different types.
A single gene disorder is one that is caused by a defect in 1 particular gene

Autosomal Recessive (AR)
Autosomal Dominant (AD)
X-linked (XL)
Y linked (YL)

Define teratogenesis

Define teratogenesis
The process by which congenital malformations are produced in an embryo or fetus.

Describe a GTG/GTW karyotype

Describe a GTG/GTW karyotype
**Human chromosomes are described alpha-numerically
1-22 autosomes 23 sex chromosome
can also be described by the position of the centromere

Describe the Factors that affect frequency of variants in a population

Describe the Factors that affect frequency of variants in a population
Selection - positive or negative
Mutation - chance
Genetic drift - the population size is sharply reduced (bottleneck effect)/ group splits from main population, found a colony (founder effect).
Gene flow - migration

Describe the structure and function of chromosomes

Describe the structure and function of chromosomes
Chromosomes are made of light and dark bands, P (short) arm and q arm:
Centromere
Telomeres at ends
Coding genes
Non-coding regions

They are involved in cell divison

Distinguish between Disruptions, Deformations, Malformations

Distinguish between Disruptions, Deformations, Malformations
Disruption: A defect: an interference with normal developmental process
Deformation: A defect: non-disruptive mechanical forces on a normal tissue/structure
Malformation: A defect: intrinsically abnormal tissue(s)

Dominant Negative Effect: where the […] produces an […] which […]

Example:
[…]

Dominant Negative Effect: where the pathogenic variant in one allele produces an abnormal product which interferes with the function of the normal product produced by the other normal allele

Example:
Osteogenesis imperfecta

Dynamic mutation is associated with […]

Dynamic mutation is associated with anticipation

“In genetics, anticipation is a phenomenon whereby as a genetic disorder is passed on to the next generation, the symptoms of the genetic disorder become apparent at an earlier age with each generation. In most cases, an increase in the severity of symptoms is also noted.”

Explain the mechanisms of genomic imprinting

Explain the mechanisms of genomic imprinting
Modification of a gene depending on its parent of origin
Methylation of CpG residues near the promoter region of the SNRPN gene occurs during the formation of ovum but not sperm
alters the structure of the chromatin>less open>prevents transcription of maternal allele

Females have more variable phenotypes in X-linked recessive because of
[…]

Females have more variable phenotypes in X-linked recessive because of
X-inactivation (Lyonization)
Homozygosity (rare)

General causes of malformations?

General causes of malformations?
Single gene, chormosome, multifactorial, mitochondrial disorders

teratogens

Who knows!

Genomic imprinting is set during […]

Once imprinted, the signal is […] and maintained during subsequent […]

This parent of origin imprint is only erased and reset in cells that […]

Genomic imprinting is set during gametogenesis

Once imprinted, the signal is set for life and maintained during subsequent DNA replication

This parent of origin imprint is only erased and reset in cells that undergo gametogenesis

Germline mosaicism is said to occur when a person has at least […]

An individual who has germline mosaicism may have […] of the disorder

Implications on the risk of having an affected child:
[…], there is a risk that the gametes produced will contain the pathogenic variant

Germline mosaicism is said to occur when a person has at least two genetically different cell populations

An individual who has germline mosaicism may have **no or little evidence **of the disorder

Implications on the risk of having an affected child:
**If cells containing the pathogenic variant exist in the gonad, **there is a risk that the gametes produced will contain the pathogenic variant

Give examples of dynamic mutations that give rise to diseases

How is Metabolic syndrome screening done?

How is Metabolic syndrome screening done?
Newborn should be on full feeds
Test done at day 2-5 of life, or at discharge
Use a special filter paper card

How is Mitochondrial Genome related disease transmitted?

How is Mitochondrial Genome related disease transmitted?
Through the maternal line

How to treat Mitochondrial Disease?

How to treat Mitochondrial Disease?
Treat the symptoms

**Some treatment may be therapeutic:
Patients with complex I and/or complex II deficiency may benefit from oral riboflavin
Supplements with ubiquinone (coenzyme Q10, ubidecarenone) are usually well tolerated and some individuals report a subjective benefit while on treatment. **

In a female cell, only one X chromosome is active at any time T/F?

In a female cell, only one X chromosome is active at any time T/F?
T

In most dominant disorders, the homozygotes are […] than the heterozygotes

In a few disorders, the homozygotes and the heterozygotes are […] affected
e.g.
Huntington Chorea
Multiple Endocrine Neoplasia I (MEN I)

In most dominant disorders, the homozygotes are more affected than the heterozygotes

In a few disorders, the homozygotes and the heterozygotes are similarly affected
e.g.
Huntington Chorea
Multiple Endocrine Neoplasia I (MEN I)

Individuals with down syndrome are prone to early onset dementia. T/F?

[…]

Individuals with down syndrome are prone to early onset dementia. T/F?

True

Mitochondrial diseases due to:

nuclear DNA mutations will manifest in […]

mt DNA mutations will manifest in […]

Mitochondrial diseases due to:

nuclear DNA mutations will manifest in childhood

mt DNA mutations will manifest in late childhood/adult life

Nuclear DNA accounts for more mitochondria, so it makes sense to appear earlier than mt DNA mutations.

Mitochondrial disorders may present at any age. T/F?

Mitochondrial disorders may present at any age. T/F?
T

Most down syndrome children are conceived by mothers less than 35 years. T/F?

[…]

Most down syndrome children are conceived by mothers less than 35 years. T/F?

True!!

> 35 years old higher risk but more children are born by mothers <35 years old, so in terms of absolute numbers, this statement is true.

Most foetuses with Down Syndrome spontaneously miscarry. T/F?

[…]

Most foetuses with Down Syndrome spontaneously miscarry. T/F?

True

80%

Name examples of diseases related to imprinting?

Name examples of diseases related to imprinting?
Prader-Willi Syndrome
Angelman Syndrome

Prader-Willi Syndrome
Rare genetic disorder
Clinical features
Intellectual disability
Short stature
Small hands and small feet
Initial inability to feed that later develops into an insatiable appetite, thus predisposing to morbid obesity and all its health consequences

Of the proteins in the respiratory chain
[…] proteins by the nuclear genome
[…] proteins by the mitochondrial genome

Of the proteins in the respiratory chain
74 proteins by the nuclear genome
13 proteins by the mitochondrial genome

One group of diseases that show dynamic mutations is the […]

One group of diseases that show dynamic mutations is the trinucleotide repeat diseases

The opposite is true for the following diagram

Outline the possible clinical presentations of chromosomal disorders

Outline the possible clinical presentations of chromosomal disorders
Infertility (can’t conceive) - 2-4% of infertile couples have a chromosomal abnormality
Spontaneous miscarriage - 15% of pregnancies end in miscarriages. Half of these miscarriages are due to chromosomal abnormalities (most of which are due to spontaneous mutations)
Still Birth - 5% of stillborn babies have a chromosomal abnormalities
Abnormal baby at birth - Present early in life with growth and development problems
Normal

Note that should parents conceive a child w problems, important to screen parental chromosomes to predict their risk of having another child w chromosomal variant

Patients with genetic conditions often wander through the healthcare system for a long time before getting a correct diagnosis (i.e. a diagnostic odyssey.) What is the average length of a diagnostic odyssey in a mature healthcare system?

[…]

3-5 years

Not trivial question. Came out in exam LOL.

Rubella in the 3rd trimester will not result in much permanent organ damage. T/F?

[…]

Rubella in the 3rd trimester will not result in much permanent organ damage. T/F?

True

Most susceptible period is 3rd-10th week after conceiving (5th-12th week after last period) because that is when organogenesis happens.

The proteins that make up the mitochondrial respiratory chain are encoded by both the nuclear and mitochondrial genome T/F?

The proteins that make up the mitochondrial respiratory chain are encoded by both the nuclear and mitochondrial genome T/F?
T

The proteins that make up the mitochondrial respiratory chain are encoded by both the nuclear and mitochondrial genome. T/F?

The proteins that make up the mitochondrial respiratory chain are encoded by both the nuclear and mitochondrial genome. T/F?
T

The Y Chromosome contains […] genes, which code for only […] proteins

deletion of the […] arm of Y chromosome gives rise to […]

The Y Chromosome contains 78 genes, which code for only i proteins

deletion of the q arm of Y chromosome gives rise to infertility

Since females are fine without having a Y chromosome, the Y chromosome must code for genes that are either specific to male function or are nonessential

What are the four tested diseases that are X-linked recessive

What are the four tested diseases that are X-linked recessive
**Red-green colour blindness
G6PD deficiency
Duchenne muscular dystrophy
Haemophilia A

What are the general principles of the pathogenesis of IEMs?

What are the general principles of the pathogenesis of IEMs?
Their signs and symptoms are a result of one or more of the following mechanisms:
- Accumulation of a normal substrate
-* Accumulation of a minor substrate as a result of shunting*
- Lack of a product
- Secondary metabolic phenomenon - shunting interferes with a different pathway

What are the risk factors for having a child with chromosomal disorders?

What are the risk factors for having a child with chromosomal disorders?
Parental chromosomal structure/number
Maternal age (increases with maternal age) - down’s syndrome ^
Paternal age (weak contributor) - chance of point mutations increased
The structure of genome - some regions more prone to errors and translocations
Other genes - missing DNA repair genes etc

What are the types and origin of chormosomal abnormalities? Give an example of a disease from each

What are the types and origin of chormosomal abnormalities? Give an example of a disease from each
Types of abnormalities
Numerical – gains are better than loss, can gain one or two e.g. down’s/or a whole set or two whole sets (usually fatal)
Structural – pathogenic or benign e.g. Deletion of the end of chromosome 4 (4p- syndrome)->developmental delay, risk of seizure

Origin of abnormalities
Constitutional (i.e. born with) Trisomy 21, Monosomy X
Acquired (i.e. not born with) Chronic Myeloid Leukemia and a chromosome translocation ,t(9;22).

What is a complex disease?

What is a complex disease?
Complex = a condition that cannot be explained by the effect of a single gene
Disease= a disorder of structure or function

What is Population Genetics?

What is Population Genetics?
Population genetics is a field of genetics that studies the genetic variations within and between population and how it changes/remains over time and place

When do you suspect mitochondrial respiratory chain diseases?

When do you suspect mitochondrial respiratory chain diseases?
When the blood lactate is high
When it fits one of the classic descriptions
When there is a disease that is progressive and involves multiple organ systems

Myopathic features such asptosis, external ophthalmoplegia, proximal myopathy and exercise intolerance, cardiomyopathy,
Neurological features such as fluctuating encephalopathy, seizures, dementia, migraine, stroke-like episodes, ataxia, spasticity, sensorineural deafness, optic atrophy, pigmentary retinopathy
Diabetes mellitus
Mid and late pregnancy loss

many individuals do not fit neatly into one particular syndrome

Which of these 5 viruses is the most common identifiable cause of congenital infection?

Varicella
Mumps
CMV
Rubella
HIV

[…]

Which of these 5 viruses is the most common identifiable cause of congenital infection?

Varicella
Mumps
CMV
Rubella
HIV

CMV

Keyword is COMMON.

Varicella only if mother suay suay kena infected 5days-2weeks before delivery
MMR in NCIS, most individuals vaccinated.
HIV low prevalence rate in general.

Why do many AD disorders show variability in the phenotype, both within the family and between families?

Why do many AD disorders show variability in the phenotype, both within the family and between families?
Incomplete/reduced penetrance
amongst 100 females who all have a pathogenic BRCA1 variant, only 60 females will develop breast cancer

Sex-dependent penetrance
Amongst 100 males who each has a pathogenic BRCA1 variant, almost none will develop breast cancer

Age-related penetrance
Persons with NF-1 are born without any feature of the disease but all will develop significant features by age 20 years old.

Variable expression (most common reason)
Individuals with NF-1 have different numbers of spots, lumps, freckling
Possible mechanisms
Genetic heterogeneity
Gene-gene interactions
Gene-environment interactions

Woman who has a son with DMD is almost always a carrier. T/F?

[…]

Woman who has a son with DMD is almost always a carrier. T/F?

**FALSE!!! **

Spontaneous mutation in 33% of DMD cases.

WRT to Characteristics of AR Disorders, Parents of the affected are […] and are usually […]

Both sexes are equally […]

In some AR conditions, heterozygotes may have […]

WRT to Characteristics of AR Disorders, Parents of the affected are asymptomatic carriers and are usually phenotypically normal

Both sexes are equally affected

In some AR conditions, heterozygotes may have some mild manifestations but these features are not the full manifestation of the condition

X Chromosome contains […] genes

X Chromosome contains ~500 genes

Most of these genes are found only on the X chromosome (i.e. not found on the Y chromosome)

A small number of genes on the X chromosome have a related copy on the Y chromosome
So females and males have 2 alleles each

X inactivation happens all the time. T/F?

X inactivation happens all the time. T/F?
F. Inactivation begins soon after fertilization and ends by the first week of development

X-Inactivation can be reversed. T/F?

X-Inactivation can be reversed. T/F?
F. The process is random but once inactivated, the inactivation is permanent

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Genetics (Integration) Rapid Fire Genetics Flashcards

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