USMLE Step 1 - uWorld High Yield Notes
What is the biochemical problem in Lesch-Nyhan syndrome? (And, only if you got that right, what are
the really cool symptoms of it?) - Defective purine catabolism, so buildup of purines. It's an X-
linked recessive disorder with mutated HGPRT gene (hypoxanthine-guanine phosphoribosyltransferase, if
you want to impress people).
What is the defect in Chronic Granulomatous disease? What is the pathophysiology? - NADPH
Oxidase deficiency leads to the inability to kill intracellular organisms
What are the two major microtubular motor proteins? Which does anterograde axonal transport, which
does retrograde axonal transport? - Kinesin, Dynein
Kinesin: Anterograde
Dynein: Retrograde`
What do you think, immunologically speaking, when you see someone with recurrent Neisseria
infections? - Inability to form the membrane attack (MAC) complex
this is a common complement deficiency
Characteristic triad of ataxia telangiectasia? - cerebellar ataxia, telangiectasias, increased risk of
sinopulmonary infections
What is the major immune deficiency of ataxia telangiectasia? - IgA deficiency, which predisposes
to infections of the upper and lower airways (and other mucous membranes)
There's a useful mnemonic for Ataxia Telangiectasia and the gene that's mutated. What is it? -
ATM
Ataxia
Telangiectasia
,Mutated
ATM gene is responsible for DNA break repair
What is one reason that lead intoxication causes hypochromic anemia? - Mitochondrial iron
transport is important for Heme synthesis! It's inhibited by lead. So you don't make heme in your
mitochondria and you get hypochromic anemia.
Now, if you got HGPRT and purine catabolism right, you can say: self-mutilating behavior on top of
mental retardation, choreoathetoid (think Chorea) movements and spasticity.
What is the defect in Niemann-Pick disease?
What causes that?
What is the common macular finding? - Sphingolipid degradation is defective
Caused by an autosomal recessive defect in sphingomyelinase
Cherry Spot on the macula? Niemann Pick's or Tay Sach's.
If a baby gets exposed to an unclean knife (...) and subsequently develops rigid paralysis, what is the
diagnosis, where do we think this might happen, and how do we prevent it? - Neonatal Tetanus
Developing Countries
Maternal immunization with tetanus toxoid is the best way to prevent it
an adeuately immunized mom will transfer IgG's across the placenta to the neonate
Which microtubule associated protein aids in anterograde transport of intracellular vesicles and
organelles? Which end of the microtubule do they go towards? - Kinesin.
Towards the (+) rapidly growing end.
What is an early BRAIN finding of Ataxia-Telangiectasia and how does it manifest itself? -
Cerebellar atrophy
,manifests as ataxia in the first years of life.
High yield path association for Alzheimer's disease? - Neurofibrillary tangles in the neocortex
High yield path association for Parkinson's disease? - Loss of neurons in the substantia nigra
High yield path association for Huntington disease? - Atrophy of caudate nucleus
What are the major manifestations of Ataxia-telangiectasia? - cerebellar ataxia, oculocutaneous
tenlangiectasias, repeated sinopulmonary infections, and an increased incidence of malignancy
If you heard: amenorrhea, bitemporal hemianopsia, and enlargement of the pituitary gland on brain
imaging, what would you be thinking? - Prolactinoma, the most common pituitary adenoma.
What embryological layer is the anterior pituitary derived from? - Surface ectoderm
What is the most common congenital abnormality associated with the use of Sodium Valproate during
pregnancy? - neural tube defects, e.g., meningocele
because valproate inhibits intestinal folic acid absorption resulting in teratogenicity
What is the characteristic histology of a craniopharyngioma? - On light microscopy, cysts are lined
by stratified squamous epithelium, possibly with Keratin perals. Cysts are usually filled iwth a yellow,
viscous fluid that's rich in cholesterol crystals.
Where do craniopharyngyomas arise from? - Craniopharyngiomas are calcified cystic tumors that
arise from remnants of Rathke's pouch (embryonic precuros of the anterior pituitary)
Failure of what process leads due neural tube defects? What can be seen in the amniotic fluid due to
leakage of fetal cebebrospinal fluid? - Failure of fusion of the neuropores.
, Alpha-fetoprotein and Acetylcholinesterase may appear in the amniotic fluid
Can a competent patient refuse healthcare? Can a competent patient refuse knowledge of their
potential health situation? - yes and yes
What is the consensus and professional standard regarding the receiving of gifts from patients? -
Don't do it. It's unethical to accept individual gifts from patients, especially of signficant value.
AMA doesn't have clear cut answer, but they recommend careful consideration be used. some general
guidelines:
-cash gifts should never be accepted (this includes gift certificates)
-a gift should never influence treatment
-no specific dollar value is given; but as a rule of thumb, it shouldn't be above patient's or physician's
means
-psychiatrist must be super careful even with small gifts
-maintain consistency among all patients
-if physician would be embarrassed or uncomfortable if his colleagues found out about the gift, don't
accept it
Is displacement a mature or immature defense mechanism? What is displacement? - Immature. A
patient redirects emotions from the person or object that's causing the emotions (e.g., wife), but who it
woudl be completely unacceptable to direct those emotions toward, to a more acceptable, but still
inappropriate, person or object (e.g., a wall or a vase).
Is sublimation a mature or immature defense mechanism? How does it work? - Mature.
Unacceptable drives are redirected toward completely acceptable targets. (Workout hard if you're angry)
Is projection a mature or immature defense mechanism? What is it? - Immature. Unacceptable or
personally disagreeable impulses are attributed to others; e.g., a student who wants to cheat on a test
accuses his classmates of cheating. Or the gayness thing
