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COM - GI Final > Genetics Of The GI - Cole > Flashcards

Genetics Of The GI - Cole Flashcards

1
Q

Where does the aganglionic segment extend to in the short-segment form?

Long-segment?

A

Not beyond upper sigmoid

All the way to proximal to the sigmoid

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2
Q

What happens in hirschprungs?

A

Meissner’s and Myenteric plexus knocked out (results in clinical manifestation)

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3
Q

What is the clinical presentation of Hirschprung’s?

A

Intestinal obstruction, megacolon

Colon distention due to lack of peristalsis

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4
Q

What syndrome is most commonly associated with Hirschprung’s?

Who does it affect the most often?

A

Down syndrome

Males

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5
Q

What gene mutation is most commonly associated with Hirschsprung’s?

What protein function?

What frequency?

A

RET

Try Kinase receptor

70-80%, 50% familial, 15-20% sporadic

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6
Q

What kind of gene is the RET?

Where is it expressed?

GOF or LOF?

A

Proto-oncogene - regulates cell growth

Neural crest cells

LOF

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7
Q

What does the RET gene provide instructions for?

Without RET signaling, what does not develop properly?

A

Producing a protein that is involved in signaling within cells, including nerves in the intestine

Enteric nerves do not develop properly

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8
Q

What genes is responsible for hereditary hemochromatosis?

A

C282Y (92%)

H63D

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9
Q

What does AAT deficiency cause?

A

Jaundice and cirrhosis

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10
Q

How is iron transported?

Where is it stored?

A

Transferrin

Ferritin in liver and heart

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11
Q

How is it possible to get rid of iron?

A

Loss of enterocytes
Blood loss
Pregnancy

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12
Q

What can happen if too much iron is absorbed?

A

Tissue damage and fibrosis

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13
Q

What happens if too many erthrocytes are destroyed?

A

Accumulate in recticuloendothelial macrophages first

Tissue parenchyma after macrophages

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14
Q

What is secondary hemochromatosis due to?

A

Build of iron due to anemia, chronic liver disease, hep C, alcoholism, or frequent blood transfusions

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15
Q

Which genes are important for iron absorption regulation?

A

HFE, HJV, HAMP, TFR2

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16
Q

Which gene is responsible for regulating Hepcidin?

A

HAMP

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17
Q

What gene is responsible for most juvenile hemochromatosis?

A

HJV

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18
Q

Which gene is less common but with similar clinical presentations to the most common gene abnormality?

A

TFR2

19
Q

What gene is responsible for the most common form of iron overload?

A

HFE

20
Q

What is a protein involved in the uptake of transferrin-bound iron into cells?

Via what mechanism?

A

TFR2

endocytosis

21
Q

What is an iron-binding blood plasma glycoproteins that controls the level of free iron in biological fluids?

A

Transferrin

22
Q

What is a protein required for iron import from transferrin into cells?

Via what mechanism?

A

TFR1

Endocytosis

23
Q

What protein functions to regulate circulating iron uptake by regulating the interaction of TFR1/2 with transferrin?

A

HFE

24
Q

In Fe deficient states, describe Hepcidin and what is happening

A

Hepcidin low, ferroportin allows transfer of Fe from cells to blood

25
Q

In Fe excess states, describe what hepcidin is doing

A

Hepcidin high, degrades ferroportin transporters

26
Q

Mutations in what genes will result in low Hepcidin levels despite high iron levels?

A

HFE
HJV
TFR2

27
Q

Describe the relationship between transferrin binding and TFR1, TFR2, and HFE

A

Transferrin prefers TFR2 > TFR1 > HFE

28
Q

If HFE is unbound, what does this stimulate?

A

Hepcidin expression

29
Q

When does onset of hemochromatosis begin? Later in who?

What symptoms?

Progresses to what?

A

Late onset (40s-50s), later in females

Non-specific symptoms

Hepatosplenomegaly

30
Q

What is the one definitive sign of Hemochromatosis?

A

Iron Fist, pain in pointer and middle knuckle

31
Q

What does intracellular iron lead to?

A

INC free radical production and peroxidation of phospholipids of mitochondria, lysosomes, microsomes

32
Q

What does increased intracellular iron lead to?

A

Increased collagen synthesis -> fibrosis and cirrhosis

33
Q

What is the treatment for hemochromatosis?

A

Therapeutic blood removal

34
Q

Which group of people have an increased prevalence of hereditary hemochromatosis?

Is it homo or heterozygous?

A

Northern Europeans

EITHER ONE

35
Q

Where is copper absorbed?

What is it bound to?

Where is it transported?

A

Stomach and duodenum

Albumin

Liver

36
Q

What are the 2 genes involved in copper homeostasis?

A

ATP7A

ATP7B

37
Q

Where is ATP7B located?

ATP7A?

A

Liver, brain, kidney, placenta

Most cells

38
Q

What is the major copper-carrying protein in the blood?

A

Ceruloplasmin

39
Q

What does Ceruloplasmin do to iron?

A

Oxidizes it, Fe2+ -> Fe3+

40
Q

Which gene is mutated in Menkes syndrome?

What is the problem?

Clinical presentation?

A

ATP7A

Failure to absorb copper (uptake impaired)

Kinky, spiky, short, sparse, blonde hair, healthy for 2-3 months then dead by age 3

41
Q

What additional clinical signs are associated with Menkes syndrome?

A

Vascular tortuosity
Laxity of skin
Occipital horns

42
Q

What gene is mutated in Wilson’s disease?

What is the problem?

Clinical signs?

A

ATP7B

Failure to excrete copper (Cu cannot be released from hepatocytes)

Kayser-Fleischer ring around cornea, neurological disorders, psychiatric symptoms

43
Q

What is the treatment for Wilson’s disease?

Menke’s Tx?

A

Copper chelation

Daily copper injection

44
Q

What are the 2 forms of Hirschprung Disease?

Which is more prevalent?

A

Short and long-segment

Short-segment

COM - GI Final (5 decks)

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