Genetics Flashcards

(35 cards)

1
Q

What is a Genotype?

A

the genetic makeup of a person

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2
Q

What is a Phenotype?

A

the physical manifestation of an inherited trait or disease

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3
Q

When do you consider a referral to genetics? (6)

A
  • developmental delay
  • dysmorphic features
  • congenital malformations
  • a positive family history of a genetic disorder
  • recurrent miscarriages/still births
  • consanguinity
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4
Q

What are some disorders that become more common due to founder effect/consanguinity? (6)

A
  • Ashkenazi Jewish: Tay-Sachs, BRCAI
  • Mediterranean: beta-thalassemia
  • Southeast Asian: alpha-thalassemia
  • Amish/Mennonite and Arab: various rare disorders
  • African: sickle cell anemia
  • Caucasian: cystic fibrosis
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5
Q

What are G/Giemsas?

A

Banded Chromosomes

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6
Q

What are the largest chromosome pairs?

A

Number 1

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7
Q

What are the smallest chromosome pairs?

A

Number 2

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8
Q

Which chromosomes determine sex?

A

Chromosome 23

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9
Q

What are the different Chromosomal Disorders?

A
  • Numerical Chromosome Anomaly
  • Structural Anomaly
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10
Q

What is Numerical Chromosome Anomaly?

A

Error which occurs in Meiosis (1 or 2), resulting in aneuploidy (monopsony or trisomy) or triploidy

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11
Q

What is Structural Anomaly?

A

Error of recombination

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12
Q

What is the most common cause of Trisomy 21?

A

Nondisjunction

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13
Q

What is Trisomy 21?

A

When a person has an extra chromosome 21
Results in Down syndrome

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14
Q

What are the characteristics of Down Syndrome?

A
  • distinct facial features
  • developmental delay
  • heart defects
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15
Q

In which population is Trisomy 21 most common? (3)

A
  • Mothers of advanced maternal age
  • due to cell division completing in mothers after ovulation and further after fertilization
  • with time, those chromosomes become very sticky as the age of the egg advances
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16
Q

What are the different ways Trisomy 21 can occur? (3)

A
  • nondisjunction
  • Translocation
  • Mosaic
17
Q

What are Structural Chromosome Anomalies? (3)

A
  • Caused by error of recombination
  • May be balanced - translocation (reciprocal or robertsonian) or inversion
  • may be unbalanced - deletion, duplication, translocation, inversion
18
Q

What are the different Chromosome Disorders? (4)

A
  • Trisomy 13
  • Trisomy 18
  • Turner Syndrome (45x)
  • Klinefelter Syndrome 47, XXY
19
Q

What is Trisomy 13? (5)

A
  • also known as Palau Syndrome
  • Midline defects are common
  • extra fingers
  • 80-90% die in first year
  • Severe developmental delay
20
Q

What is Trisomy 18? (5)

A
  • also known as Edward Syndrome
  • Most are female (5:1)
  • Frequent cardiac defects
  • 80-90% die in first year of life
  • Marked developmental delay
21
Q

What is Turner Syndrome? (7)

A
  • disorder in which there is only one X chromosome
  • puffy hands and feet at birth
  • webbed neck
  • coarctation of aorta
  • short stature
  • primary amenorrhea and infertility (streak ovaries)
  • Normal intelligence
22
Q

What is Klinefelter Syndrome? (7)

A
  • disorder in which there is an extra X chromosome XXY
  • Tall stature
  • Excess breast development
  • small testes
  • infertility
  • normal appearance
  • may have learning disabilities
23
Q

Who is the father of Genetics?

A

George Mendel

24
Q

What did George Mendel do?

A

He worked with seven characteristics of pea plants, and crossed them to see what he could get, looking at the genetics

25
What is Autosomal Dominant? (5)
- Diseases/disorders that run in families - usually present in every generation - not tied to a X chromosome - Males and females are affected equally - about 50% transmission
26
What is an example of an Autosomal Dominant Disease?
Polycystic Kidney disease
27
What is Autosomal Recessive? (4)
- diseases/disorders in which the person inherits two changed genes - majority of people are carriers, but it does not affect their health - Males and females are effected equally - Consanguinity increase the number of individuals affected
28
What is an example of Autosomal Recessive Disease?
Cystic Fibrosis
29
What is Cystic Fibrosis? (3)
- When we have mutations or changes in the gene CFTR - It codes for the CFTR protein which is responsible for chloride channels - it starts to affect the mucus and motility of the cilia
30
What are the characteristics of an X-linked Inheritance? (4)
- Males affected almost exclusively - the gene alteration can be transmitted from female carriers to sons, but the females are often asymptomatic - affected males cannot transmit the condition to their sons - carrier females may be mildly affected or fully affected due to skewed X inactivation
31
Why are males affected by X-linked disorders?
- only 1 X chromosome - must express all x-linked genes - hemizygous
32
What is Duchenne Muscular Dystrophy? (5)
- X-linked disorder that impacts the gene called DMG - this gene codes for dystrophin, which is important in the muscles - affected males die in their early 20s due to cardiomyopathy - mutation may be inherited from mother or new mutation - high spontaneous mutation rate
33
What occurs in boys who have Duchenne Muscular Dystrophy?
- They will present early on with progressive breakdown of muscles - One of the signs is hypertrophy, fatty tissue as opposed to muscle - progressive muscle weakness
34
What are the characteristics of Mitochondrial DNA Disorders? (4)
- all mitochondria are inherited from the mother through the egg - mitochondria have their own circular DNA - expectation is to have maternal inheritance, and all her offspring will have it/carry it - severity depends on the abnormality of the mitochondria genetic material
35
What are the Symptoms of Mitochondrial Multi-systemic Disorders? (6)
- Muscle = fatigue and low tone - Brain = cognitive dysfunction - Digestive = feeding difficulties, constipation - Cardiac = cardiomyopathy - Eye = limited eye movement - Diabetes