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Unit 2 M2M > Unit 2 Day 7 > Flashcards

Unit 2 Day 7 Flashcards

1
Q

medelian inheritance

A

how hereditary characteristics are passed from parent to offspring

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2
Q

law of segregation

A
  • every individual possesses pair of alleles for any trait

- each parent passes randomly selected copy of one to offspring

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3
Q

law of independent assortment

A
  • separate genes for separate traits
  • passed independently of one another from parent to offspring
  • alleles of diff genes assort independently
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4
Q

autosomal dominant

A
  • maps to autosome
  • homo/heterozygotes
  • equal m/f
  • passed either parent
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5
Q

penetrance

A
  • probability that mutant allele /s will have phenotypic expression
  • 100% any person shows some symptom
  • less than 100% some carry mutation show no symptoms
  • often reduced penetrance
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6
Q

expressivity

A

severity of manifestation of phenotype among individuals with same disease causing genotype

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7
Q

achondroplasia

A
  • autosomal dom
  • skeletal dysplasia
  • 80% mutation rate
  • 100% penetrance
  • 1/15000-40000 newborns
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8
Q

de novo mutation

A
  • mutations occur in egg or sperm after fertilization

- explain autosomal dominant in child w/unaffected parents

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9
Q

achondroplasia manifestations

A
  • short stature
  • limb/finger shortening
  • genu varum
  • trident hands
  • large head w/ facial retrusion
  • small foramen magnum
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10
Q

achondroplasia mutation

A
  • FGFR3 (fibroblast growth factor receptor 3)
  • regulates bone growth
  • chromosome 4p16.3 (1138 position causes)
  • aa substitution–>missense mutation
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11
Q

what is the highest new mutation rate in male sperm?

A

nt 1138 of FGFR3 gene

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12
Q

retinoblastoma

A
  • tumor of retina
  • 1/15000 births
  • RB1 gene on ch 13
  • protein regulates cell cycle
  • 90% penetrance (incomplete)
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13
Q

neurofibromatosis type 1

A
  • autosomal dominant
  • 1/3000 births
  • 50% mutation
  • variable expressvity
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14
Q

diagnostic criteria of NIH

A

must have 2 or more

  • 6 or more café-au-lait spots
  • 2 or more neurofibromas
  • 1 plexiform neurofibroma
  • Freckling in the axillary or inguinal area
  • Optic glioma
  • 2 or more Lisch Nodules
  • Distinctive osseous lesions
  • Affected first degree relative
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15
Q

neurofibromatosis type 1 mutation

A

NF1

  • tumor supressor gene
  • ch 17q11.2
  • loss of function
  • considered dominant
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16
Q

locus heterogeneity

A
  • mutation in >1 locus causes same clinical condition

- mutations in 1 gene and another, cause same mutation

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17
Q

Tuberous Sclerosis

A
  • autosomal dom
  • 1/6000
  • variable expressivity
  • 2/3 is de novo
  • fully penetrant
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18
Q

TS skin findings

A
  • hypopigmented patches
  • angiofibroma
  • shagreen patch
  • ungual fibroma
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19
Q

Tuberous Sclerosis issues

A
  • Kidneys: renal cysts, angiomyolipomas
  • Lungs: Lymphangioleiomyomatosis
  • heart: Cardiac rhabdomyoma
  • CNS issues
  • seizures
  • neuropsychiatric disorders
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20
Q

clinical criterial for TS

A

must have one major and 2 minor features

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21
Q

major features TS

A 
Angiofibromas
Cardiac rhabodmyoma
Cortical dysplasias
Hypomelanotic macules
Lymphangioleiomyomatosis
Multiple retinal nodular hamartomas
Renal angiomyolipoma
Shagreen Patch
Subependymal nodule
SEGA
Ungual Fibroma
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22
Q

minor features TS

A 
Confetti skin lesions
Dental Enamel pits (>3 teeth must be present to see)
Intraoral fibromas
Multiple renal cysts
Nonrenal hamartomas
Retinal achromic patch
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23
Q

TS mutation

A
  • TSC1 and 2
  • hamartin, tuberin proteins
  • cell growth/proliferation regulation
  • ch 9, 16
  • loss of function
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24
Q

osteogenesis Imperfecta type 1

A
  • autosomal dom
  • 1/30,000-50,000
  • variable expressivity
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25
Q

clinical manifestations of osteogenesis imperfecta

A
  • multiple fractures
  • short stature
  • hearing loss (adult onset)
  • blue sclera
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26
Q

Osteogenesis imperfecta mutation

A
  • COL1A1
  • collagen type 1 alpha 1
  • ch 7q21.3
  • reduced production pro-alpha 1 chains
  • collagen production reduced by 1/2
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27
Q

Marfan Syndrome

A
  • autosomal dom
  • 1/5000 births
  • 25% new mutation rate
  • variable expressivity
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28
Q

marfan clinical manifestation

A
  • disorder connective tissue
  • ocular
  • skeletal
  • cardiovascular
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29
Q

marfan mutation

A
  • FBN1 (fibrillin-extracellular matrix protein)
  • ch 15q21.1
  • dominant negative activity
  • reduction in microfibrils
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30
Q

trinucleotide repeat disorders

A
  • segment of DNA consisting of 3 or more nuts
  • slipped mispairing
  • anticipation
  • parental transmission bias
  • AD, AR, X linked transmission
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31
Q

slipped mispairing

A
  • mispairng of bases in regions of repetitive replication coupled with inadequate repair systems
  • as repeat grows, probability increases
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32
Q

anticipation

A
  • severity/onset of disease increases next generation

- increase in number of copies

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33
Q

parental transmission bias

A

-trinucleotide expansion more prone to occur in gametogenesis of m/f

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34
Q

huntingtons

A
  • autosomal dom
  • tnr disorder (CAG)
  • 1/10000
  • anticipation
  • parent of origin affects (early onset-paternal, late-maternal)
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35
Q

clinical manifestation huntingtons

A
  • progressive neuronal degeneration
  • 34-44 age of onset
  • death 15 yrs after onset
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36
Q

huntingtons muation

A
  • HTT
  • ch 4p16.3
  • expansion of glutamine may cause an altered structure or biochemical property of protein
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37
Q

myotonic dystrophy type 1

A
  • autosomal dom
  • tnr disorder (CTG)
  • 1/20000
  • anticipation
  • maternal transmission
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38
Q

clinical manifestations of myotonic dystrophy type 1

A
  • adult onset
  • progressive muscle wasting/weakness
  • myotonia
  • cataracts
  • cardiac conduction defects
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39
Q

mutations in MD1

A
  • DMPK (myotonic dystrophy protein kinase)
  • ch 19q13.3
  • plays role in muscle, heart, brain cells
40
Q

MD1 CTG repeat

A
  • 5-24=normal
  • 34-49=premutation
  • > 50=full mutation, 100% penetrance
41
Q

x chromosome inactivation

A
  • only one copy of majority of genes on x chromosome is necessary
  • 2 copies=detrimental
  • one turned off==barr body
  • occurs 1st week of embryogenesis
  • 50:50 complement (if off can be bad)
  • XIST gene inactivates
42
Q

with skewed x chromosome inactivation what happens?

A
  • observed when female shows sign or symptoms of x-linked recessive condition
  • eg: duchene MS
43
Q

x-linked disorders

A
  • x chromosome mutations
  • male affected mostly
  • male-male transmission
  • hemizygous for mutations in x-linked genes
44
Q

x-linked recessive inheritance

A
  • phenotype expressed in all males who carry
  • expressed in only homozygous females
  • hetero females are carriers
45
Q

x-linked dominant

A
  • hypophosphatemic rickets
  • alport syndrome
  • fragile x
  • charcot marie tooth
  • incontinentia pigmenti
  • rett syndrome
  • orofaciodigital syndrome
  • focal dermal hypoplasia
46
Q

hypophosphatemic rickets

A
  • x linked dom
  • 1/20000
  • short stature
  • bone deformity
47
Q

hypophosphatemic rickets mutation

A
  • PHEX gene
  • regulates fibroblast growth factor
  • inhibits kidneys to reabsorb phosphate
48
Q

fragile X syndrome

A
  • x linked com
  • FMR1 gene
  • tnr disorder-CGG
  • 1/2500-4000 males
  • 1/7000-8000 fem
  • most common cause inherited developmental delay males
  • anticipation
  • maternal transmission bias
49
Q

fragile x clinical manifestation

A
  • intellectual disabilities
  • dysmorphic features
  • autistic
  • socially anxious
  • hand flapping/biting
  • agression
50
Q

FMR1 associated conditions

A
  • FXTAS (fragile x associated tremor ataxia syndrome)

- primary ovarian insufficiency

51
Q

rett syndrome

A
  • x linked dom
  • 1/10000 females
  • 95% mutation rate
  • loss normal movement coordination
  • microcephaly
  • loss comm skills
  • failure to thrive
  • seizures
  • abnormal hand movements
52
Q

rett syndrome mutation

A
  • gene MECP2
  • methyl CpG binding protein
  • normal function nerve cells necessary
  • boys don’t live
53
Q

x linked recessive disorders

A 
Lesch-Nyhan Syndrome
Dystrophinopathies
Hunter’s Disease
Menkes Disease
Glucose 6 phosphate dehydrogenase deficiency
Hemophilia A and B
Wiscott Aldrich Syndrome
Colorblindness
54
Q

lesch-nyhan syndrome

A
  • x linked
  • 1/380000
  • cerebral palsy
  • uric acid overproduction
  • self injury
  • cognitive issues
55
Q

lesch-nyhan mutation

A
  • HPRT1

- recycles purines

56
Q

dystrophinopathies

A
  • x linked recessive
  • spectrum m. disease
  • 3 distinct conditions: duchenne, Becker, DMD cardiomyopathy
57
Q

dystrophinopathies mutation

A
  • DMD gene, x chromosome
  • ch Xp21-21.1
  • dystrophin
  • largest human gene
58
Q

DMD

A
  • duchenne muscular dystrophy
  • progressive muscular weakness
  • calf hypertrophy
  • CK levels 10x normal
  • onset before age 5, wheelchair before 13
  • absence of dystrophin causes death 30’s
59
Q

Becker muscular dystrophy

A
  • similar symptoms, later onset to DMD
  • CK levels 5x normal
  • wheelchair bound after 16
  • death in 40’s
  • abnormal quantity/quality of dystrophin
60
Q

DMD-associated DCM

A
  • present btw. 20-40 years
  • early death
  • no sm involvement
  • no dystrophin in myocardium
  • female carriers affected w/ cardiomyopathy
61
Q

hemophilia A

A
  • x linked recessive
  • 1/4000 male births
  • 10% female carriers affected
  • can’t clot, excessive bruising, royal fam
62
Q

hemophilia A mutation

A
  • gene F8 on x chrom
  • Xq28
  • deficiency factor 8
  • 22A inversion causes 50%
63
Q

mitochondria

A
  • perform oxidative phosphorylation
  • encodes 37 genes
  • produce components respiratory chain
  • maternal inheritance
  • replicative segregation
  • threshold effect
  • affected females pass to all children
64
Q

replicative segregation

A
  • at cell division, multiple copies of mtDNA

- replicate/randomly sort among newly synthesized mitochondria

65
Q

heteroplasmy

A

-presence of more than 1 type of organellar genome within cell or individual. important factor in considering the severity of mitochondrial diseases

66
Q

mitochondrial disease

A
  • group disorders caused by dysfunction of respiratory chain

- disorders tend to affect tissues that rely on oxidative phosphorylation

67
Q

Kearns-Sayre Syndrome

A
  • mitochondrial
  • 1-3/100000
  • most commonly caused by somatic mutation
  • triad
  • cardiac conduction defects, ataxia, deafness, kidney issues
  • large deletion of mtDNA
  • removes 12 genes most commonly
68
Q

MELAS

A
  • mitochondrial encephalomyopathy, lactic acidosis, and stroke-lie episodes
  • 1/300000
  • low new mutation rate
  • can present in children btw 2-10 years
  • muscle weakness, seizures, strokes, lactic acidosis
  • multiple mitochondrial genes
69
Q

MERRF

A
  • myoclonic epilepsy with ragged red fibers
  • mitochondrial inheritance
  • 1/400000
  • low new mutation rate
  • muscle symptoms, seizures, ataxia, dementia
  • mitochondrial gene mutations
  • MT-TK
70
Q

Leber Hereditary Optic Neuropathy

A
  • mitochondrial inheritance
  • 1 in 30-50000 europeans
  • bilateral subacute vision failure
  • occurs young adulthood
71
Q

effects of paternal grandparent diet on grandchildren

A
  • good or poor diet during the slow growth period had effect on pre-adolescence
  • increased mortality associated with feast year
72
Q

genetic mother mouse feeding tests

A
  • mice fed with high methyl donor ingredients=larger, light offspring
  • AGOUTI gene turned off in lower methyl donor diet offspring
73
Q

epigenetic characteristics

A
  • different gene expression pattern/phenotype, identical genome
  • inheritance through cell division, even through generations
  • like a switch-on/off (not gradient, gene itself is on/off)
  • erase-able (inter-convertible, reversible)
74
Q

wadding tons landscape as epigenetic visualization

A
  • cell can go to various states
  • think of in terms of energy states
  • each cell is existing in stable low-energy state
  • go from pleuripotent to differentiated
75
Q

epigenetic gene expression patterns

A

-cell differentiates, some “light switches”/genes go off/on

76
Q

DNA methylation

A
  • locks in repressed state
  • occurs on cytosines of CpG
  • doesn’t affect base pairing of 5-meC with G
  • contributes to gene silencing by solidifying the repressed state
  • requires cofactor SAM
  • can be changed by diet/smoking
77
Q

maintenance methyltransferases and epigenetic markers

A
  • occurs at level of DNA replication-all epigenetic inheritance begins
  • menthyl grops are programmed for inheritance to occur
  • prevents methyl group from being diluted
78
Q

histone H3 modifications affect gene expression

A
  • repressive histone marks-off
  • active histone marks-on
  • ones sticking out from the strand are easiest to modify
79
Q

inheritance of chromatin state

A
  • dna methylation begins at replication
  • 2 sister chromatins made result in large disturbance to chromatin
  • must maintain nucleosome modifications
  • newly made histones must be induced to maintain what type they are (since combo of half old/half new)
80
Q

epigenetic phenomena

A
  • chromatin-mediated gene silencing
  • dosage compensation v. important
  • important factor in many diseases
81
Q

silencing of tumor suppressor gene

A
  • 5meC can lead to cancer
  • unmethylated–>methylated
  • enzymes maintain repression-histone deacytelases
82
Q

epigenetic therapy

A
  • disrupt tumor suppression

- combinational therapy on multiple regulatory mechanisms

83
Q

causes of genetic disease

A
  • alteration of DNA changes products (mRNA, protein)

- mutations that alter functional proteins

84
Q

loss of function mutations

A

-single gene disorders almost always result from mutations in the function of a protein

85
Q

what are the 4 common mechanisms of human genetic disease?

A
  • no gene
  • no rna
  • no protein
  • protein nonfunctional
86
Q

DMD Xp21.2

A

-sex linked
-premature termination from nonsense/stop mutations, frameshift, deletions
-gower maneuver
-boys
duchenne muscular dystrophy
-frameshift-lof mechanism

87
Q

hereditary neuropathy with liability to pressure palsies

A
  • deletion of pmp22 gene-lof
  • integral membrane protein in glycoprotein nerves
  • autosomal dominant
  • incomplete recovery
  • arm numbness that never comes back
88
Q

what happens with unequal crossing over between 17p12?

A
  • pmp22 gene
  • supposed to line up normally-misalign
  • crossover that can occur, duplication or deletion
89
Q

allelic disorders

A
  • conditions genetically related

- HNPP and CMT1A are in sense that diff mutations in same gene lead to diff phenotypes

90
Q

osteogenesis imperfecta type 1

A

-normal state-make 3 polypeptide chains, 2 pro alpha, 1 pro alpha
-important structure in our bones
-termination codon that is premature
-dominant
COLA1 makes 2, COLA2 make 1

91
Q

hemoglobin kempsey

A
  • beta hemoglobin gene
  • Asp99Asn missense mutation
  • higher O2 affinity
  • prevents shift from locked to relaxed, gain of function
  • unloads less O2 in tissues
92
Q

charcot marie tooth syndrome

A
  • type 1A
  • duplication PMP22 gene
  • gain of function
  • autosomal dom
  • presents lower extremities with weakness and muscle atrophy and mild sensory loss
93
Q

novel property mutations

A
  • eg: sickle cell anemia
  • mutation: no effect O2 carrying
  • novel property of polymerizing under low O conditions
  • long hemoglobin polymers
94
Q

Osteogenesis imperfecta type 2, 3, 4

A
  • make COL1A1 okay, but the second one you make abnormally
  • novel property mutation
  • better to have half the amount of normal collagen, than produce bad trimers
95
Q

hereditary persistence of fetal hemoglobin

A
  • altered or ectopic expression
  • binds tightly
  • protective against malaria
  • normal product expressed at the wrong time
96
Q

trinucleotide repeats

A
  • affect different parts of the gene

- knowing locations may shed light on underlying mechanisms

Unit 2 M2M (8 decks)

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