Genetics Flashcards

1
Q

What is meant by a monogenic gene disorder?

A

Due to a single gene mutation

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2
Q

What are the 6 patterns of inheritance by which a monogenic gene disorder can be passed on?

A
Autosomal Dominant
Autosomal Recessive
X linked dominant
X linked recessive
Y-linked
Mitochondrial
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3
Q

What is meant by a polygenic gene disorder?

A
  • Multiple genes involved
  • Often environmental influences
  • Evaluated by looking at large populations
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4
Q

Describe what is meant by high penetrance?

A

If the patient has the gene mutation they are extremely likely to have the disease

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5
Q

If both parents are carriers for a recessive mutation, what is the likelihood of the child inheriting the disease?

A

1 in 4

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6
Q

Autosomal dominant usually skips generations. TRUE/FALSE?

A

FALSE

usually appears in every generation

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7
Q

If males can only pass a genetic disorder to females, but females can pass it to either sex, what pattern of inheritance is this?

A

X-linked dominant

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8
Q

If males are always affected, yet females can become carriers, what pattern of inheritance does this describe?

A

X-Linked Recessive

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9
Q

If only males are affected by a genetic disease, what does this indicate about its inheritance pattern?

A

It is Y-linked as only males have a Y-chromosome

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10
Q

Describe what is meant by a mitochondrial inheritance pattern

A

Inherited through mother’s mitochondrial DNA whilst in the womb
=> can only inherit it from mother

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11
Q

Explain what benign tumours usually present in Multiple Endocrine Neoplasia Type 1 (MEN1)

A

Benign:

  • Non-secreting Islet cell tumour
  • Non-secreting pituitary tumour
  • adrenal cortex
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12
Q

What malignant tumour usually presents in MEN1?

A

Foregut carcinoid tumour

secretes gastrin, glucagon and polypeptides

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13
Q

What benign or malignant tumours are found in Multiple Endocrine Neoplasia Type 2?

A

C-cell

Adrenal Chromaffin

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14
Q

What gene defect is found in Multiple Endocrine Neoplasia Type 2?

A

RET

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15
Q

What hormones are secreted in Von Hippel Lindau syndrome?

A

Catecholamines

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16
Q

What type of gene is the MEN1 gene

A

A tumour suppressor

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17
Q

What section of the MEN1 gene is usually mutated in Multiple endocrine Neoplasia Type 1?

A

11q

18
Q

Both MEN1 and MEN2 are autosomal dominant. TRUE/FALSE?

A

TRUE

19
Q

What section of the RET gene is usually mutated in MEN2 and what type of gene is it?

A

10q

RET = proto-oncogene

20
Q

MEN mutations in MEN1 usually occur in very specific areas of the codon. TRUE/FALSE?

A

FALSE
RET mutations in MEN2 act in very specific cysteine residues, whereas in MEN1 they can occur anywhere along the length of the codon.

21
Q

What three areas are usually affected by tumours in MEN1?

A

Pituitary
Pancreas
Parathyroid

22
Q

What tumour found during MEN1 is the most fatal?

A

Pancreatic neuroendocrine tumour

23
Q

After what size should an MEN1 pancreatic tumour be referred for surgical intervention?

A

> 2cm

24
Q

What tumours usually present in MEN2a?

A

Parathyroid hyperplasia
Medullary Thyroid Carcinoma
Phaechromocytoma

25
Q

What tumours are usually present in MEN2b?

A

Mucosal Neuromas
Medullary Thyroid Carcinoma
Phaechromocytoma
Marfan’s Syndrome is also present

26
Q

What prophylactic treatment can be used in MEN2 for Medullary Thyroid Cancer?

A

Prophylactic Thyroidectomy

27
Q

At what age is it important to screen for Phaechromocytoma and Parathyroid disease?

A

Between ages 11 and 16
>11 = High Risk
>16 = moderate Risk

28
Q

How do patients with Carney Complex usually present?

A

Spotty pigmentation of the skin:

  • lips
  • eyes
  • genitals
29
Q

Where do myxomas usually present in Carney Complex patients?

A

Breast
Cardiac

generally myxomas can be cutaneous or mucosal

30
Q

What cancers often present in the Carney Complex

A

Thyroid carcinoma

GH producing pituitary Adenoma (causing Acromegaly)

31
Q

What feature of the Carney Complex leads to the development of Cushing’s syndrome?

A

Primary pigmented nodular adrenocortical disease

PPNAD causes adrenal glands to produce excess cortisol
=> Cushing’s syndrome

32
Q

What subunit involved GPCR signalling caused uncontrolled proliferation in the Carney complex?

A

Protein Kinase A (PKA) regulatory subunit

33
Q

WHat are the usual presenting features of McCune-Albright syndrome?

A
  • Café-au-lait skin pigmentation (looks like Maine coast)
  • Polyostotic fibrous dysplasia (bones)
  • Precocious puberty (typically females)
  • Thyroid nodules
  • GH excess
  • Cushing’s syndrome (adrenal)
34
Q

When does the mutation in McCune-Albright syndrome occur?

A

Post-zygotic somatic mutation

=> not inherited from mother

35
Q

What gene is affected in Von Hippel Lindau syndrome and what inhertance pattern does it exhibit?

A

VHL gene

Autosomal Dominant

36
Q

What type of tumour is most common in VHL?

A

Vascular tumours
e.g. Retinal Haemangiomas
CNS Haemangioblastomas

37
Q

What signs are often seen in Neurofibromatosis Type 1?

A
Axillary freckling
Café-au-lait patches
Neurofibromas
Optic gliomas
Scoliosis
 Some learning difficulties
38
Q

What rare type of cancer can present in Neurofibromatosis Type 1?

A

Phaeochromocytoma (rare)

39
Q

What is a phaechromocytoma usually referred to as?

A
The tumour of 10
e.g.
10% malignant
10% bilateral
10% extra-adrenal
10% familial
etc.
40
Q

What gene mutations commonly cause Paragangliomas?

A

SDHA, SDHB, SDHC, SDHD

Succinate Dehydrogenase A,B,C,D

41
Q

What Succinate Dehydrogenase mutation is worst to have and why?

A

SDHB

most likely to cause malignancy (B for Bad)

42
Q

What succinate Dehydrogenase mutation can be inherited from a father?

A

SDHD

D for Dad