Cystic fibrosis

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Cystic fibrosis

Genetics

Population genetics

Mendelian genetics and punnett squares

Hardy-Weinberg equilibrium

Inheritance patterns

Independent assortment of genes and linkage

Evolution and natural selection

Genetic disorders

Down syndrome (Trisomy 21)

Edwards syndrome (Trisomy 18)

Patau syndrome (Trisomy 13)

Fragile X syndrome

Huntington disease

Myotonic dystrophy

Friedreich ataxia

Turner syndrome

Klinefelter syndrome

Prader-Willi syndrome

Angelman syndrome

Beckwith-Wiedemann syndrome

Cri du chat syndrome

Williams syndrome

Alagille syndrome (NORD)

Achondroplasia

Polycystic kidney disease

Familial adenomatous polyposis

Familial hypercholesterolemia

Hereditary spherocytosis

Huntington disease

Li-Fraumeni syndrome

Marfan syndrome

Multiple endocrine neoplasia

Myotonic dystrophy

Neurofibromatosis

Treacher Collins syndrome

Tuberous sclerosis

von Hippel-Lindau disease

Albinism

Polycystic kidney disease

Cystic fibrosis

Friedreich ataxia

Gaucher disease (NORD)

Glycogen storage disease type I

Glycogen storage disease type II (NORD)

Glycogen storage disease type III

Glycogen storage disease type IV

Glycogen storage disease type V

Hemochromatosis

Mucopolysaccharide storage disease type 1 (Hurler syndrome) (NORD)

Krabbe disease

Leukodystrophy

Niemann-Pick disease types A and B (NORD)

Niemann-Pick disease type C

Primary ciliary dyskinesia

Phenylketonuria (NORD)

Sickle cell disease (NORD)

Tay-Sachs disease (NORD)

Alpha-thalassemia

Beta-thalassemia

Wilson disease

Fragile X syndrome

Alport syndrome

X-linked agammaglobulinemia

Fabry disease (NORD)

Glucose-6-phosphate dehydrogenase (G6PD) deficiency

Hemophilia

Mucopolysaccharide storage disease type 2 (Hunter syndrome) (NORD)

Lesch-Nyhan syndrome

Muscular dystrophy

Ornithine transcarbamylase deficiency

Wiskott-Aldrich syndrome

Mitochondrial myopathy

Autosomal trisomies: Pathology review

Muscular dystrophies and mitochondrial myopathies: Pathology review

Miscellaneous genetic disorders: Pathology review

Assessments

Cystic fibrosis

Flashcards

0 / 19 complete

USMLE® Step 1 questions

0 / 13 complete

High Yield Notes

13 pages

Flashcards

Cystic fibrosis

of complete

Questions

USMLE® Step 1 style questions USMLE

of complete

A 14-year-old boy is brought to the clinic by his parent for a routine checkup. The patient has cystic fibrosis and has had multiple hospitalizations in the past for pulmonary infections. The patient is currently on albuterol, inhaled N-acetylcysteine, oral ibuprofen, and a combination of lumacaftor and ivacaftor. The patient states he feels fine today. Vital signs are within normal limits. Weight is at the 10th percentile for age and height is at the 10th. Digital clubbing is present. The patient’s parent recently read about the medication dornase alfa that is supposedly effective in treating cystic fibrosis. The mechanism of action of which of the following medications is most similar to dornase alfa?  

External References

First Aid

2022

2021

2020

2019

2018

2017

2016

Amenorrhea

cystic fibrosis p. 58

Azithromycin

in cystic fibrosis p. 58

Biliary cirrhosis p. 398, 402

cystic fibrosis p. 58

Bronchiectasis

cystic fibrosis p. 58

Bronchitis

cystic fibrosis p. 58

Burkholderia cepacia

cystic fibrosis p. 176

Chloride channels

cystic fibrosis p. 58

Cirrhosis p. 398

cystic fibrosis p. 58

Clubbing (nails)

cystic fibrosis p. 58

Cystic fibrosis p. 58

Aspergillus fumigatus p. , 150

bronchiectasis p. 700

chromosome association p. 62

common organisms p. 176

meconium ileus in p. 395

N -acetylcysteine p. 711

pancreatic insufficiency p. 390

vitamin deficiencies and p. 63

Hypokalemia p. 615

cystic fibrosis p. 58

Infertility

cystic fibrosis p. 58

Liver disease

cystic fibrosis p. 58

Meconium ileus p. 395

cystic fibrosis p. 58

N -acetylcysteine p. 711

for cystic fibrosis p. 58

Nasal polyps

cystic fibrosis p. 58

Pediatric patients

cystic fibrosis p. 58

Pseudomonas spp.

cystic fibrosis p. 58, 176

Sodium channels

cystic fibrosis p. 58

Staphylococcus aureus p. , 133

cystic fibrosis p. 58, 176

Steatorrhea

cystic fibrosis p. 58

Streptococcus pneumoniae p. , 134

cystic fibrosis p. 176

Transcript

Content Reviewers

Rishi Desai, MD, MPH

Tanner Marshall, MS

Kara Lukasiewicz, PhD, MScBMC

Contributors

Tanner Marshall, MS

You’re probably aware that cystic fibrosis, or CF, is a genetic disorder that affects the lungs, but that’s only part of the story.

In fact, the name “cystic fibrosis,” refers to the disease’s effects on the pancreas, where it can lead to cysts, which are fluid-filled sacs wrapped in a membrane and fibrosis—excess deposition of connective tissue that can replace or infiltrate normal tissue in an organ.

CF is an autosomal recessive disorder involving the CFTR gene, which stands for “cystic fibrosis transmembrane conductance regulator,” and this gene codes for the CFTR protein.

CF develops when there’s a mutation in the CFTR gene, but because it’s autosomal recessive, you need to inherit two mutated CFTR genes, one from mom and one from dad.

Now if mom and dad both have one copy of the mutated gene and one normal gene, they’re considered carriers and don’t have the disease.

Inheriting CF is more common in people of European descent.

The CFTR protein is a channel protein that pumps chloride ions into various secretions, those chloride ions help draw water into the secretions, which ends up thinning them out.

The most common mutation is the “∆F508” mutation.

Delta means a deletion, and the F (which can also be written as “Phe”) is short for phenylalanine, and the 508 is the five hundred and 8th amino acid in the CFTR protein.

So, the ∆F508 mutation is where the 508th amino acid out of 1480, phenylalanine, is deleted and missing.

This CFTR protein with the ∆F508 mutation gets misfolded and can’t migrate from the endoplasmic reticulum to the cell membrane, meaning there’s a lack of CFTR protein on the epithelial surface, and this means that it can’t pump chloride ions out, which means water doesn’t get drawn in, and the secretions are left overly thick.

In a newborn, thick secretions can affect the baby’s meconium, or first stool, or, which can get so thick and sticky that it might get stuck in the baby’s intestines and not come out, and this is called a meconium ileus and is a surgical emergency.

In early childhood, pancreatic insufficiency is the most prominent effect of CF.

Sources

  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "Cystic Fibrosis: Lessons from the Sweat Gland" Physiology (2007)
  6. "Infection Control in Cystic Fibrosis" Clinical Microbiology Reviews (2004)
  7. "Pharmacological approaches for targeting cystic fibrosis nonsense mutations" European Journal of Medicinal Chemistry (2020)
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