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Block 3 Found Sci > Genetic Disorders > Flashcards

Genetic Disorders Flashcards

1
Q

autosomal dominant

definition

A

only one good gene so heterozygotes
-will go thru all generations, both sexes
-may have delayed onset
-reduced production or inactive proteins

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2
Q

marfan syndrome gene problem

A

chromosome 15 (long arm) missense mutation in gene that encodes fibrillin-I
-no cystine for disulfide bonds, glycine instead so disordered = weak elasticity

auto dominant

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3
Q

fibrillin-I function

A

part of microfibrils aka elastic fibers in connective tissue

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4
Q

where fibrillin-I is found

A
  1. aorta (cardiovasc probs)
  2. suspensory ligament of lens (ocular probs)
  3. periosteum covering bones (skeletal)
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5
Q

fibrillin-1 mutation effects

A
  1. stiffening aortic wall
  2. inc TGF-beta1 activity
  3. inflamm, matric metallo proteases
  4. elastolysis, cell disarray
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6
Q

ocular symptoms marfan

A

displaced lens (ectopia lentis) so myopia

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7
Q

skeletal symptoms marfan

A
  1. long slender limbs (dolichostenomelia)
  2. pectus carinatum (pigeon)
  3. pectus excavatum (hollow chest)
  4. scoliosis
  5. spinder fingers (arachnodactyly)
  6. joint hypermobility
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8
Q

cardiovascular symptoms marfans

A
  1. mitral valve prolapse-mitral regurgitation
  2. dilation of ascending aorta @ root > valve incompetence > dissection/rupture
  3. cardiomyopathy- left vent enlarges as aorta widens
  4. congestive heart failure
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9
Q

criteria for marfan diagnoses

A

either 4 major features or 1 major 2 minor

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10
Q

major skeletal criterion

marfans

A
  1. pectus carinatum
  2. pectus excavatum (surgery)
  3. arm L greater than height (ULSR)
  4. wrist and thumb sign
  5. scoliosis or spondylolisthesis
  6. reduced elbow extension
  7. pes plenus
  8. protrusio acetabulae
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11
Q

other major criterion marfans

A
  1. lens dislocation
  2. dilation aortic root, dissection ascending aorta
  3. lumbosacral dural ectasia
  4. inheritance in family
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12
Q

minor criterion marfans

A
  1. pectus excavatum (no surgery)
  2. joint hypermobility
  3. high palate with dental
  4. crowding
  5. facial characteristics
  6. flat cornea
  7. mitral valve prolapse
  8. dilate pulmonary A or calcified mitral annulus below age 40
  9. recurrent or incisional hernia
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13
Q

mitral valve histology marfans

A

parachute appearance
-will close mid systole and hear click
-regurg into L atrium

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14
Q

cystic medial degeneration

marfans

A

elastic fibers are disrupted by pools of blue mucinous ground substance

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15
Q

type I and II ehlers danlos syndrome

classic

A

defective type V collagen, reduced amount

mutations in COL5A1/2 that encode alpha chain of type V
-reduced COL5A1 mRNA

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16
Q

type IV ehlers danlos syndrome

vascular

A

dec amount of type III collagen, collagen made but not exits the cell
-gene defect COL3A
-deadly

17
Q

type VII ehlers danlos syndrome

arthrochalasia VIIa,b

A

cant turn procollagen into collagen
-amino terminal procollagen peptidase deficiency so cant cleave

18
Q

EDS type I characteristics

A

-stretchy skin
-disorganized collagen, bear paw appearance

19
Q

general EDS symptoms

A
  1. hyperelasticity- stretchy skin
  2. hypermobility- unusual extension, flexion of joints
  3. skin fragility- small injuries lead to serious wounds bc wound healing faulty
  4. sutures not hold well (dehiscence)
  5. tendency to bleed (bleeding diathesis type IV)
20
Q

beighton scale for joint hypermobility

A

total score of at least 5 to dx

1 point for unilateral, 2 for bilateral
-flexion of 5th finger and thumb
-hyperextension elbow and knee
-forward flexion of trunk with knees full extended and palms on floor

21
Q

neurofibromatosis type 1

NF1

A

highly variable expression + complete penetrance
-high mutation rate, half are new mutations

22
Q

neurofibromin normal function

A

downregs function of p21 ras oncoprotein
-encodes GTPase activating protein that converts active ras-GTP to inactive ras-GDP
-aka when ras not inactivated = tumor

on chromosome 17q

23
Q

expressions of NF1

A

-cafe au lait macules
-lisch nodules
-neurofibromas
-optic gliomas
-malignancies (malignant peripheral nerve sheath tumors from plexiform neurofibromas)
-learning disabilities
-scoliosis

only 10% or less dev malignancies

24
Q

NF1 dx criteria

A

2+ present
1. 6 cafe au lait macules
2. freckling @ armpits or groin
3. 2+ neurofibromas OR 1 plexiform
4. 2+ lisch nodules @ eye
5. optic glioma
6. bone lesions (sphenoid, tibia)
7. first degree relative with NF

25
Q

schwannoma vs neurofibroma

A

-schwannoma = only schwann cells, enculeate out , suppress nerve fibers
-neurofibromas = mix of schwann, perineurial, fibroblasts, and mast cells, prolif within nerve fibers (resection)

26
Q

NF2 genetics

A

-20% of sporadic cases are actually mosaic for mutation

inactivating merlin/schwannomin tumor suppressor = NF2 associated and sporadic tumors

27
Q

merlin function

A

bound to CD44 membrane signaling protein and actin
-will detatch from actin and inactivate Ras

28
Q

symptoms of NF2

A
  1. bilateral vestibular schwannomas aka acoustic neuromas (impact CN VIII)
  2. low grade CNS tumors
  3. meningiomas
  4. ependymomas
  5. gliomas
29
Q

criteria for definite NF2

A
  1. bilateral vestibular schwannomas OR family history of NF2
  2. plus unilateral schwannoma before 30 or any two of meningioma, glioma, schwannoma, juvenille posterior subcapsular lenticular opacities
30
Q

criteria for probable NF2

A
  1. unilateral vestibular schwannoma before 30 + one of (miningioma, glioma, schwannoma, juvenille lenticular opacities)
  2. or 2+ meningiomas + unilateral vestibular schwannomas before 30 or one of (glioma, schwannoma, juvenille lenticular opacities)
31
Q

presentation of symptoms NF2

A

hearing loss
-unilateral at onset > complete deafness
-VS also cause tinnitus, dizziness, imbalance

32
Q

NF2 tumor appearance

A

multifocal or bunch of grapes
-VS more lobular and less vascular than sporadic

intracranial meningioma, spinal tumors, cutaneous tumors but more subtle than NF1

vestibular schwannomas

33
Q

vestibular schwannoma features

A
  1. antoni A-dark staining, have verocay bodies (two lines of nuclei)
  2. antoni B- light staining

Block 3 Found Sci (60 decks)

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