Pulmonology · USMLE Step 1 and Step 2

Cystic Fibrosis song

Cystic Fibrosis - Genetics & Management, as a song. Hear the short teaser here. The full song is on YouTube and Spotify.

Cystic Fibrosis

Full song on YouTube ↗Spotify ↗

Key points in this song10

Cystic fibrosis is caused by a mutation in the CFTR gene on chromosome 7, most commonly the ΔF508 mutation, which causes misfolding and retention of the chloride channel in the endoplasmic reticulum.
CFTR normally functions as a cAMP-regulated chloride channel; in CF, defective chloride secretion leads to thick, dehydrated mucus due to increased sodium and water reabsorption.
Classic presentation includes chronic sinopulmonary disease, pancreatic exocrine insufficiency (steatorrhea, fat-soluble vitamin deficiencies), and elevated sweat chloride >60 mEq/L on pilocarpine iontophoresis.
Recurrent pulmonary infections follow a classic progression: Staphylococcus aureus in childhood, then Pseudomonas aeruginosa (mucoid form) in adolescence and adulthood.
Meconium ileus in a newborn is pathognomonic for cystic fibrosis until proven otherwise.
CF causes obstructive lung disease on PFTs with decreased FEV1/FVC ratio; bronchiectasis develops over time from chronic inflammation and infection.
Pancreatic exocrine insufficiency leads to deficiencies of fat-soluble vitamins A, D, E, and K; vitamin K deficiency manifests as coagulopathy with elevated PT.
Males with CF are infertile due to bilateral absence of the vas deferens (CBAVD), while females have reduced fertility from thickened cervical mucus.
CF-related diabetes mellitus results from destruction of pancreatic islets by fibrosis and is unique in that both insulin deficiency and exocrine insufficiency coexist.
Ivacaftor (potentiator) and lumacaftor/tezacaftor (correctors) are CFTR modulators; elexacaftor/tezacaftor/ivacaftor (Trikafta) is effective for ΔF508 homozygotes and is the current standard of care.