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Block 4: SD 2 Week 11 > GI Genetics > Flashcards

GI Genetics Flashcards

1
Q

Be able to explain the dietary factors that lead to increased risk of colorectal cancer.

A
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2
Q

Most colorectal cancers occur due to inherited conditions or sporadic?

A

sporadic conditions

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3
Q

What are inherited conditions that can lead to colorectal cancers?

A

FAP (familial adenomatous polyposis)
Lynch Syndrome HNPCC

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4
Q

HNPCC is associated with what type of mutations?

A

mismatch repair gene mutations (MMR)

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5
Q

FAP is associated with what type of gene mutations?

A

APC gene mutations

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6
Q

A count of about how many polyps is necessary for a diagnosis of FAP to be made?

A

100 polyps

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7
Q

Be able to explain and understand the process in this diagram.

A

Understand diagram well

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8
Q

Describe some characteristics of Gardner syndrome.

A

*multiple colorectal polyps

*osteomas

*soft tissue tumors

-epidermoid cysts

-fibromas

-Desmoid tumors

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9
Q

What are some characteristic features of Turcot syndrome.

A

multiple colorectal polyps

brain tumors

medulloblastoma
glioma

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10
Q

What is Cowden syndrome?

A

inherited condition that is characterized primarily by multiple, noncancerous growths (called hamartomas) on various parts of the body

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11
Q

What are most cases of Cowden syndrome caused by? (mutations in what gene) Also what is the inheritance pattern of Cowden Syndrome?

A

Most cases are caused by mutations in the PTEN gene and are inherited in an autosomal dominant manner.

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12
Q

Cowden syndrome is associated with an increased risk of developing what type of cancer?

A

particularly cancers of the breast, thyroid and the lining of the uterus (the endometrium).

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13
Q

What does HNPCC stand for? Another name for HNPCC?

A

Hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome

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14
Q

What ages to colon cancers in patients with HNPCC start? Where are they usually located?

A

younger ages than sporadic colon cancers

often located in rt colon

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15
Q

Places or pattern of organs/ organ systems Lynch Syndrome can be found in?

A

colon, uterine, endometrial, ovarian, stomach, renal cancer etc

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16
Q

The majority of individuals with Lynch syndrome possess at least one pathogenic germline mutation of what genes?

A

MMR (mismatch repair genes)

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17
Q

What are the most commonly mutated MMR genes in Lynch syndrome?

A

MLH1 and MSH2 genes

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18
Q

What is the inheritance pattern of Wilson disease?

A

AR

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19
Q

What is Wilson disease?

A

disorder of copper transport, resulting in copper accumulation and toxicity to the liver and brain.

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20
Q

What is the common mutation found in Wilson Disease?

A

ATP7B gene mutation

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21
Q

What chromosome has the affected gene mutation in Wilson disease?

A

13q14.3

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22
Q

Describe pathology of ATP7B gene.

A
  1. gene provides instructions for making a protein called copper-transporting ATPase 2, which plays a role in the transport of copper from the liver to other parts of the body.
  2. copper-transporting ATPase 2 protein is particularly important for the elimination of excess copper from the body.
  3. Mutations in theATP7Bgene prevent the transport protein from functioning properly.
  4. With a shortage of functional protein, excess copper is not removed from the body.
  5. As a result, copper accumulates to toxic levels that can damage tissues and organs, particularly the liver and brain.
23
Q

Some neurologic presentation of Wilson’s Disease?

A

Neurologic presentations include movement disorders (tremors, poor coordination, loss of fine-motor control, chorea, choreoathetosis) or rigid dystonia (mask-like facies, rigidity, gait disturbance, pseudobulbar involvement).

24
Q

What is hemochromatosis?

A

Disorder of iron overload

25
Q

How does hemochromatosis occur?

A

excess iron absorbed from gut

26
Q

What gene is defective in hemochromatosis?

A

HFE gene on chromosome 6

27
Q

Role of HFE gene in aiding in iron homeostasis?

A

HFE protein normally limits amount of iron uptake by gut and regulates amount of iron stored in the tissues

28
Q

What are 2 common mutations in HFE?

A

C283Y allele
H63D allele

29
Q

Classic triad of symptoms characteristic of hemochromatosis?

A

cirrhosis (hepatic damage)
diabetes (pancreatic damage)
bronzing of skin (hyperpigmentation)

30
Q

What are the most commonly mutated genes present in hereditary pancreatitis?

A

most common mutations involve the PRSS1, CFTR, SPINK1, and CTRC genes.

31
Q

What is the inheritance pattern of hereditary pancreatitis?

A

Depends on mutation involved:

PRSS1 is autosomal dominant with gain-of-function variants

CFTR, CTRC, SPINK1 are autosomal recessive

32
Q

What is a major pancreatic enzyme PRSS1 encodes for?

A

encodes cationic trypsin, the most abundant isoform of trypsin secreted by the pancreas.

33
Q

Up to 80% of patients with Hereditary Pancreatitis have been found to have a mutation in what gene?

A

PRSS1 gene

34
Q

What is the role of cationic trypsin?

A

convert inactive pancreatic zymogens secreted by the pancreas into active digestive enzymes in the duodenum.

35
Q

Premature conversion of trypsinogen to trypsin leads to what complication?

A

Premature conversion of trypsinogen to trypsin leads to premature activation of these digestive enzymes before excretion from the pancreas, which in turn leads to autodigestion of the parenchyma

36
Q

What is the most common causative mutation of PRSS1 gene?

A

R122H

37
Q

What is the second most common PRSS1 mutation?

A

N29I

38
Q

What is the cytogenetic location of PRSS1 gene?

A

7q34, which is the long (q) arm of chromosome 7 at position 34

39
Q

What are ZSDs?

A

heterogenous group of AR disorders characterized by defect in peroxisome formation

40
Q

Why mutations is Zelweger syndrome caused by?

A

mutation in at least 12 different genes:

PEX1, PEX2, PEX3, PEX5, PEX6, PEX10, PEX12, PEX13, PEX14, PEX16, PEX19, PEX26. The majority of patients has either a mutation in PEX1 or PEX6

41
Q

What are some characteristic features of ZSD?

A

typically present in the neonatal period with hepatic dysfunction and profound hypotonia resulting in prolonged jaundice and feeding difficulties.

Characteristic dysmorphic features can usually be found, of which the facial dysmorphic signs are most evident

42
Q

What is the most reliable test to confirm diagnosis of ZSD?

A

The most reliable test to confirm the diagnosis of peroxisomal biogenesis disorders is the measurement of VLCFA concentrations in plasma.

Patients with Zellweger syndrome have elevated plasma concentrations of VLCFA and elevated ratios of C26 to C22 and C24 to C22 fatty acids

43
Q

The normal CFTR protein product is a chloride channel protein found in membranes of cells that line passageways of what organs?

A

lungs, liver, pancreas, intestines, reproductive tract, and skin

44
Q

Explain how Cystic fibrosis happens on a molecular level.

A

CFTR controls chloride ion movement in and out of the cell.

When a CFTR protein with the delta F508 mutation reaches the ER, the quality-control mechanism of this cellular component recognizes that the protein is folded incorrectly and marks the defective protein for degradation. As a result, delta F508 never reaches the cell membrane.

45
Q

Understand this slide.

A

Understand slide.

46
Q

What are some respiratory symptoms of CF?

A

cough that produces thick sputum and mucus
wheezing and breathlessness
repeated lung infections
stuffy nose

47
Q

What are some digestive symptoms of CF?

A
  • foul-smelling, greasy stools
  • poor weight gain and growth
  • intestinal blockage and severe constipation
48
Q

What is AATD? (inheritance pattern)

A

genetic inherited autosomal recessive condition

49
Q

What mutation is AATD caused by?

A

mutations in SERPINA1 gene located in the long arm of chromosome 14

50
Q

AATD stands for what?

A

alpha-1 antitrypsin

51
Q

Pathophysiology of AATD?

A
  • Alpha-1 Antitrypsin is an enzyme produced by the liver, and goes to the lungs through the blood stream.
  • It protects the lungs from damage by Neutrophil Elastase (NE).
  • Neutrophil Elastase is a protease (breaks down protein) produced by the WBC.
  • This genetic defect alters the configuration of the alpha1-antitrypsin molecule and prevents its release from hepatocytes.
52
Q

In AATD the most common substitution is that glutamic acid is replaced by what?

A

lysine

53
Q

What what to the AAT that cannot leave the liver? (How does it affect the liver?

A

accumulates in the liver, and causes liver damage like jaundice, cirrhosis, and increased risk of liver cancer.

54
Q

How does having AATD affect the lungs?

A

If α-1 AT is not going to the blood stream, it is not going to the lungs.

Now the NE is free to attack the lungs, and cause lung diseases such as COPD, Emphysema, Chronic Bronchitis, etc.

Block 4: SD 2 Week 11 (4 decks)

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