Foundations Exam 1 > Clinical Correlations > Flashcards

Clinical Correlations Flashcards

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1
Q

MELAS

A

Mitochondrial Encephalomyopathy with Lactic Acidosis and Stroke-like Episodes

mitochondrial inheritance

red-ragged fibers, hemiparesis, seizures

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2
Q

what illnesses do the following nucleoside analogs treat?
a. acyclovir
b. AZT
c. ddC
d. gemcitabine
e. remdesivir

A

a. acyclovir - HSV (deoxyguanosine)
b. AZT - HIV (thymidine)
c. ddC - HIV (deoxycytidine)
d. gemcitabine - cancer (deoxycytidine)
e. remdesivir - covid (adenosine)

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3
Q

function of quinolone drugs

A

block activity of DNA gyrase (prokaryotic Top II)

inhibit bacterial DNA synthesis

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4
Q

function of chemotherapeutic drugs Camptothecin and Adriamycin/Etoposide

A

Camptothecin targets Topo I

Adriamycin and Etoposide target Topo II

convert topoisomerases into DNA breaking agents by inhibiting ability of top to REJOIN DNA

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5
Q

what do inhibitors of HSV helicase-primase do?

A

stabilize interaction of helicase-primase with its viral DNA substrate

inhibiting progression of HSV DNA replication

(effective in HSV strains resistant to nucleoside-based therapies)

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6
Q

Dyskeratosis congenita

A

reduced telomerase activity —> affects stem and germ cells in tissues dividing rapidly/often

bone marrow failure due to loss of hematopoietic renewal

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7
Q

Lynch syndrome

A

HNPCC

mismatch repair (MMR) defect (shows MSI)

mutation in MSH2 or MLH1

colorectal cancer

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8
Q

mutation in DNA glycosylase MYH

A

high risk of colon cancer

defect in base excision repair (BER)

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9
Q

Werner’s syndrome

A

autosomal RECESSIVE

RecQ family WRN helicase mutation —> defect in BER

premature aging (20-30y), cataracts, atherosclerosis, cancer, telomere shortening

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10
Q

xeroderma pigmentosum (XP)

A

defect in GG-NER

XP protein mutations affecting recognition or helicase activity

solar sensitivity, skin cancer

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11
Q

cockayne syndrome

A

defective TC-NER

mutation in CSA or CSB recognition proteins

growth delays, intellectual disability, sun sensitive (but NOT cancer risk)
premature aging, from birth

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12
Q

Cisplatin

A

chemotherapeutic drug, forms bulky intra-strand adducts in DNA

treats tumors deficient in NER

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13
Q

ataxia oculomotor apraxia (AOA1)

A

autosomal RECESSIVE

mutation in aprataxin (APTX) - DNA “end processor” with hydrolase and transferase activity —> ssB repair defect

ataxia, oculomotor apraxia, hypercholesterolemia, hypoalbuminemia

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14
Q

ataxia telangiectasia (AT)

A

autosomal RECESSIVE

mutation in ATM (signal to cell cycle checkpoint, active in B/T development) —> dsB NHEJ defect

immune deficiency, chromosomal abnormalities (B, T cells), lymphoid cancer, hypersensitive to ionizing radiation

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15
Q

alpha-amanitin

A

mushroom toxin, inhibits RNA pol II

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16
Q

molnupiravir

A

covid drug (prodrug)

substrate for viral RNA-dependent RNA polymerase

causes viral mutagenesis, inhibiting viral replication

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17
Q

rifampicin

A

antibiotic specific for bacterial RNA pol

part of combination therapy for M. tuberculosis

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18
Q

Rett syndrome

A

X-linked DOMINANT** (heterogenous females only)

mutation in MECP2 (loss of methylation—> inappropriate gene expression)

begins young - seizures, lung infections, autism, failure to gain speech/walk

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19
Q

mis-regulation of transcription by HIV-1

A

programmed ribosomal frame shifting: generate >1 protein from single mRNA

pseudoknots stall ribosome

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20
Q

how does polio virus mess with translation

A

contains internal ribosome entry site (IERS) that allows cap-independent translation

cleaves eIF4G, diverts machinery, IRES binds eIF4G, direct recruitment of 40S

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21
Q

how does Corynebacterium diptheriae mess with translation

A

toxin (diphtheria) inactivates eEF-2 (transfers ADP-ribose from NAD), inhibiting translocation

presents with soar throat, grey/white pseudomembranes

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22
Q

hemochromatosis

A

autosomal RECESSIVE

defective iron storage (excess in body) - HFE mutation

phenotype varies by sex: women have mechanism to get rid of excess iron

most common single-gene inherited disease in US

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23
Q

male-limited precocious puberty

A

autosomal DOMINANT**

sex-limited, only expressed in males - early onset puberty

mutation in LH receptor (constitutively active)

females can carry but no phenotype

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24
Q

why does neurofibromatosis make creating a pedigree difficult

A

autosomal DOMINANT

but variable expressivity - all individuals affected, but severity varies

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25
Hemophilia A
*X LINKED RECESSIVE* mutation in Factor VIII (clotting) males have severe phenotype heterozygous females may have mild disease (skewed X inactivation)
26
when osteogenesis imperfecta (autosomal dominant) or Duchenne muscular dystrophy (X-linked recessive) appear in a population, the most likely cause is…
new mutation genetically lethal diseases, no inheritance pattern
27
Huntington disease
*autosomal DOMINANT*** **TNR (CAG, glutamine) in EXON of chromosome 4** —> protein misfolding, aggregation *disease with 40+ repeats* paternal transmission - expansion through *spermatogenesis* abnormal saccadic eye movements, chorea, neuronal loss in striatum, mood, behavior
28
Fragile X syndrome
**X-LINKED DOMINANT*** *TNR (CGG) in 5’-UTR* maternal transmission - expansion in *oogenesis* **pre-mutation —> primary ovarian insufficiency**, ataxia syndrome most common cause of inherited cognitive disability, *autism* *male full mutation: long face, prominent jaw, mitral valve prolapse* female full mutation: *mild cognitive disability*
29
Friedreich ataxia
*autosomal RECESSIVE* *TNR (GAA) in INTRON of chromosome 9* —> mRNA transcript lost most common cause of hereditary ataxia develops young - ataxia, *sensory loss*, mitochondrial dysfunction, *CHF*, diabetes mellitus, *progressive weakness*
30
myotonic dystrophy, type 1 (DM1)
*autosomal DOMINANT** *TNR (CTG) in 3’-UTR of DMPK* —> RNA toxicity maternal transmission (expansion) most common cause of adult-onset muscular dystrophy mild (cataracts), classic (muscle wasting, *myotonia*, *arrhythmias*), severe/congenital pronounced genetic anticipation
31
Down Syndrome: Trisomy 21
meiotic nondisjunction most common chromosomal abnormality, most frequent genetic cause of cognitive disability slanted eyes, flat face, macroglossia, nuchal folds, brachycephaly (wide), *early-onset Alzheimer’s*, hypotonia, cardiac septal defects, *duodenal atresia*, *neoplasia (leukemia)*
32
Trisomy 18
*EDWARD syndrome* meiotic nondisjunction prominent occiput, *small for gestational age*, clenched hands, rocker-bottom feet, dolichocephaly (long), severe cognitive disability
33
Trisomy 13
*PATAU syndrome* meiotic nondisjunction anophthalmia (missing eye), *cleft lip/plate*, holoprosencephaly, severe cognitive disability, *polydactyly*
34
Turner syndrome
*MONOSOMY X*: 45, X *short*, cardiovascular defect, *ovarian failure* (primary amenorrhea), lymphedema
35
47, XXY
*KLEINFELTER syndrome* *paternal* nondisjunction tall, androgen insufficiency
36
Prader-Willi syndrome
chromosome 15 PATERNAL deletion of maternally imprinted gene (Prader = Paternal) *most common form of syndromic obesity*, genital hypoplasia, neonatal hypotonia, *reach milestones late*
37
Angelman syndrome
chromosome 15 MATERNAL deletion in paternally imprinted gene (angelMan = Maternal) loss of E3 ubiquitin ligase *nonverbal*, *seizures*, happy demeanor, microcephaly, cognitive impairment
38
what goes wrong in cystic fibrosis and what is its inheritance pattern
autosomal recessive LOF mutation in CFTR Cl- channel (normal ligand is ATP) impaired channel function —> abnormal salt transport —> mucus buildup inside respiratory epithelial cells
39
what does tetrodotoxin (TTX) do?
pufferfish toxin - binds sodium ion channels irreversibly (with a large “puffed up” molecule similar to hydrated sodium) disrupts action potential propagation —> diaphragm paralysis and death
40
tamoxifen
estrogen receptor antagonist selective for breast tissue gets chaperoned into nucleus, then represses estrogen response element (DNA sequence)
41
Addison’s diseases, Cushing’s syndrome, and Kallman syndrome all have this in common
steroid-hormone related diseases Addison’s: autoimmune adrenal insufficiency Cushing’s: hyperaldosteronism (secondary) —> high ACTH Kallman: delayed puberty, developmental disorder
42
how does ras mutation play a role in cancer
ras: small G-protein in ras-MAPK pathway oncogenic mutation in ras makes it resistant to GAP —> constitutively active (common mutation in tumors)
43
cell signaling cause of neurofibromatosis type 1
mutation in GAP genes results in overactive Ras [mutation is in NF1, which encodes neurofibromin-1 GAP]
44
cell signaling mutation that causes Noonan syndrome
hyperactive Ras due to GOF mutation resulting in defective GAP activity [mutation is in PTPN11 gene which encodes protein tyrosine phosphatase SHP2] Noonan syndrome: abnormal development in various parts of body
45
hereditary spherocytosis
mutations in spectrins —> spherical RBC susceptible to destruction in spleen spectrins associate with membrane proteins to stabilize biconcave shape of erythrocyte
46
tetrodotoxin and lidocaine both exhibit this cellular effect:
sodium channel blockers tetrodotoxin: puffer fish toxin puffs up sodium channel to irreversibly block it lidocaine: anesthetic to treat tachycardia
47
effect of curare
blocks Na/K ion channel competitively antagonizes nicotinic Ach receptor at neuromuscular junction —> paralysis
48
chloroquine is frequently used to develop malaria, but resistance commonly occurs. how?
increased expression of ABC pump
49
how do these toxins target actin cytoskeleton: phalloidin, cytochalasin, latrunculin
bind and stabilize actin or block polymerization from + barbed end
50
how do Listeria and Rickettsia (rocky mountain fever) bacteria both target actin?
hijack actin polymerization machinery to make themselves an actin tail to shuttle them around spread without detection from cell to cell
51
how do each of these toxins target microtubules: paclitaxel, colchicine, vincristine
stabilize microtubules or block polymerization from + end
52
what cytoskeletal component is associated with congenital heart disease and cardiomyopathy?
actin - heavily expressed in the heart muscles for contraction
53
Griscelli syndrome Type 1 presentation and cause
silver hair, light skin, severe neurological defects defective myosin transportation of melanosome to cell periphery
54
Kartagener Syndrome
aka Primary Ciliary Dsykinesia mutations in dynein heavy chain —> immobile cilia/flagella chronic infections of respiratory tract (can’t clear it), sterile males (immobile sperm)
55
match the disease with the defective cell structure: Zellweger syndrome, I-cell disease, hypercholesterolemia lysosomes, endosomes, peroxisomes
Zellweger syndrome: defective peroxisomes - enzymes not transported into peroxisome I-cell disease: defective lysosomes hypercholesterolemia: defective endocytosis
56
Zellweger syndrome
defect in recognition signal of peroxisomal enzyme proteins - do not get delivered to peroxisome ! Zo [for Zellweger] no !! peroxisome is defective
57
botulinum and tetanus toxins affect vesicular transport by cleaving ____
v-SNARES, preventing vesicular fusion and NT release
58
Inclusion (I-cell) disease
mannose-6 residue is not phosphorylated on lysosomal proteins due to *phosphotransferase* mutation all lysosomal enzymes [very inclusive !] are secreted because they cannot be recognized by M-6-P receptor in *trans-Golgi*, so are not directed towards lysosome
59
what happens to cell function during Legionairre’s disease?
bacteria engulfed in phagosome hijack it! and block delivery to lysosome bacteria isn’t degraded so replicates instead
60
how does a mutation in LDL receptor tail prevent cholesterol clearance and cause hypercholesterolemia?
interferes with receptor binding to *adaptin* so even if cargo is bound to receptor it cannot be incorporated into vesicle for exit [clearance]
61
a patient has a mutation in Claudin 19, an important protein expressed in renal tubule tight junctions. What would you expect the effect to be?
claudins regulate paracellular permeability and reabsorption of calcium and magnesium in renal tubules would see LOW serum Mg2+ and HIGH urinary Ca2+ (neither is being reabsorbed as well)
62
what causes EMT
EMT: epitelial to mesenchymal transition, important part of cancer progression due to loss of E-cadherin (main protein for holding epithelial cells together in sheet)
63
pemphigus vs pemphigoid
pemphigus: blistering between epidermis, due to autoantibodies against spot desmosomes (intermediate filaments) pemphigoid: blistering between epidermis and dermis (between cell and basal lamina), due to autoantibodies against hemidesmosomes
64
what do osteogenesis imperfecta, chondrodysplasia, and Ehler-Danlos syndrome have in common?
tissue-specific diseases associated with mutations in fibril-forming collagens osteogenesis imperfecta: brittle bone, Type I defect (found everywhere) chondrodysplasia: Type II (cartilage) Ehler-Danlos: aneurism, Type III (aorta, blood vessels)
65
a patient comes in with scurvy. how will this affect their collagen?
scurvy: due to vitamin C deficiency vitamin C required for hydroxylation of alpha chain of collagen —> they would have reduced collagen formation
66
epiphyseal dysplasia is due to mutation in what kind of collagen (2 types)?
1. fibril-forming collagen Type II 2. fibril-associated collagen Type IX important for joints together, mutation leads to arthritis
67
how do mutations in collagens Type XVII (17) and VII (7) cause blistering diseases?
Type XVII is transmembrane collagen —> blistering between epithelium and basement membrane Type VII is network forming —> blistering between basement membrane and stroma (connective tissue)
68
Marfan syndrome
long appendages, chest deformity, aorta prone to rupture (AD inheritance) Fibrillin 1 (glycoprotein) mutation causes defect in elastin
69
cause and presentation of Epidermolysis bulbosa
Type VII (7) network-forming collagen defect epithelium and basement membrane peel away
70
Glanzmann’s disease
clotting disorder caused by mutation in integrin beta 3 inability of platelets to bind fibrinogen
71
how is Bcl-2 implicated in cancer?
high levels of Bcl-2 (anti-apoptotic) cause decreased propensity to undergo apoptosis —> increased cancer growth linked to poor disease outcomes
72
3 ways p53 helps prevent cancer formation
1. initiates apoptosis by blocking Bcl-2 and Bcl-XL while promoting Bak/Bax 2. activates DNA repair proteins 3. arrests growth by holding cell cycle at G1/S checkpoint
73
polyhydramnios vs oligohydramnios
polyhydramnios: excess amniotic fluid (might be due to fetus’ inability to swallow or esophageal-duodenal atresia) oligohydramnios: insufficient amniotic fluid
74
congenital human disorders of hedgehog signaling primarily affect what bodily regions?
CNS and limb Hh is localized to organizing centers in posterior limb bud and ventral midline of CNS during embryogenesis
75
major biological causes of human holoprosencephaly (HPE) (2)?
HPE: failure of embryonic prosencephalic vesicles to divide into 2 hemispheres major causes: 1. Shh protein haplo-insufficiency (single copy of gene is not sufficient) 2. Gli2 mutation
76
mechanism and effect of cyclopamine (plant alkaloid)
inhibits Shh signaling by blocking Smo (which Shh disinhibits by binding Ptc1) —> Gli phosphorylation into GliR occurs constitutively, target genes constantly repressed
77
Smith-Lemli-Opitz Syndrome
mutation in cholesterol synthesis [sterol delta-7-reductase] cholesterol depletion during gestation —> depleted processing of Shh (needed for auto-cleavage) limb and CNS effects, similar to Shh knockdown
78
what mutation in the Hh pathway causes medulloblastoma?
medulloblastoma: tumor in cerebellum during development LOF Ptc1 mutation —> constant disinhibition of Smo, even in absence of Hh —> target genes constitutively activated
Foundations Exam 1
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