High Yield USMLE Flashcards
What is the direct impact of absence of Y chromosome during development?
Germinal ridge develops into ovaries; presence of Y chromosome causes germinal ridge to develop into testes.
Affect of UVB light on DNA?
Thymidine dimers
Inheritance pattern for xeroderma pigmentosum?
Autosomal recessive
Pathophysiology of xeroderma pigmentosum?
Absent DNA repair enzymes leads to increased incidence of UVB-related skin cancers
Cytochrome oxidase (oxidative phosphorylation) is inhibited by what two poisons?
CO and cyanide
Inheritance pattern for chronic granulomatous disease?
Majority are X-linked recessive, remaining are autosomal recessive.
Pathophysiology of chronic granulomatous disease?
Absent NADPH oxidase leads to absent respiratory burst (ability to form reactive oxygen species) leading to susceptibility to infection by catalase-positive organisms (ex: S. aureus, Listeria, E. coli, etc.)
What percent of patients in a study fall two standard deviations below the mean in a normal distribution curve?
2.5% (5% of the population is outside of two standard deviations on either side of the mean. Therefore, the population below two standard deviations on just one side of the mean = half of 5% = 2.5%).
A family tree for a disease shows that all the children (male and female) of a female are affected by the disease, but the children (male and female) of her brother are not. What inheritance pattern does this likely represent?
Mitochondrial (all babies get their mitochondria from Mom).
Most common vitamin deficiency in alcoholics? Most common mineral deficiency in alcoholics?
Folate
Magnesium
Vitamin cofactor for major dehydrogenases (pyruvate dehydrogenase, alpha-ketoglutarage dehydrogenase, branched chain FA dehydrogenase, etc.)?
Thiamine (vitamin B1)
Which cell(s) is/are affected most by a deficient NADPH oxidase system (CGD)?
Neutrophils and monocytes
What is caisson disease?
Decompression sickness: divers who come up too fast.
What is decreased when a diver comes up too quickly (in caisson disease)? I.e. what is the pathophysiology of the disease?
P(N2) (partial pressure of nitrogen) is decreased since nitrogen forms bubbles in the vessels and moves into the tissue.
DES exposure is associated with?
Clear cell adenocarcinoma of the vagina.
What is the precursor to clear cell adenocarcinoma of the vagina?
Vaginal adenosis
If one kidney undergoes damage, what happens to the other (what will you see on imaging)?
Hypertrophy; the other kidney is enlarged on imaging.
What are three main consequences of vitamin E toxicity in terms of hematology?
- Decreases levels of vitamin K-dependent factors.
- Increases incidence of hemorrhagic stroke.
- Potentiates the action of warfarin.
Biotin (vitamin B7) is most important for what reaction?
Carboxylase reactions (ex: conversion of pyruvate to oxaloacetate in Krebs cycle).
Cherry red macula = what disease(s)?
Tay-Sachs (also Niemann-Pick and less commonly others).
How is vitamin B6 important for the liver?
Important for transamination reactions (i.e. functioning of AST and ALT).
Chance of a male patient with CF having a child?
<5% (because the vas deferens never fully developed or are atretic).
Chance of female patient with CF having a child?
Higher than males, but still difficult due to thick cervical mucus.
What vitamin supplements are required in CF?
All the fat-soluble ones (A, D, E, and K).
What cells does EBV infect? What is the receptor for EBV on these cells?
B cells; CD21.
Hypogonadism, mental retardation, and unilateral gynecomastia = ?
Klinefelter syndrome
Hypogonadism and color blindness = ?
Kallman syndrome (absent GnRH)
Hypogonadism, mental retardation, and retinitis pigmentosum = ?
Laurence-Moon-Biedl syndrome.
Male with hypogonadism, mental retardation, short stature, and webbed neck = ?
Noonan syndrome (similar to Turner’s syndrome).
Hypogonadism + anosmia (lack of smell) = ?
Kallman syndrome
Male pseudohermaphrodite with cryptorchidism = ?
Testicular feminization; most commonly due to absent androgen receptors (X-linked recessive)
Microdeletion leading to hypogonadism, mental retardation, short stature, and obesity = ?
Prader-Willi syndrome (chromosome 15, deletion is of paternal origin with maternal chromosome silenced by imprinting).
Two major complications of cyclophosphamide use?
- Hemorrhagic cystitis
2. Transitional carcinoma of bladder
Employee that work in a car assembly plant present with headache, nausea, vomiting, muscle weakness, and abdominal cramps. Coworkers have similar symptoms = ?
Lead poisoning from batteries.
Newborn female with edema of hands and feet and cystic mass of neck = ?
Turner’s syndrome (45 XO)
