Cystic Fibrosis Overview and Genetic Traits

Study Notes

Cystic Fibrosis Overview

Cystic Fibrosis (CF) is caused by mutations in the CFTR gene, which codes for a chloride channel.
It is an autosomal recessive disorder characterized by fibrosis and cyst formation in the pancreas.
CFTR is expressed in the lungs, pancreas, sweat glands, and vas deferens.

Genetic Traits

Mendelian Trait: Depend on the genotype at one locus; examples include blood groups, eye color, and Cystic Fibrosis.
Multifactorial Trait: Depend on multiple loci; examples include height, IQ, and cardiovascular disease.

Lung Function and Mucus

Mucus captures pathogens and dust, playing a crucial role in respiratory health.
Mucociliary Transport: Movement of mucus by cilia in respiratory epithelium; involves rapid forward stroke and slow recovery stroke.
Cilia beating helps move mucus upwards towards the throat; facilitated by coughing or throat clearing.

CFTR Gene and Channels

CFTR gene is located on chromosome 7 and has over 1,500 identified mutations.
Normal lung cells have two chloride channels and one sodium channel, regulated by ATP and calcium ions.
The CFTR protein regulates chloride and sodium concentrations that affect mucus osmolarity.

Impact of CF on Mucus

In CF, mutated CFTR leads to decreased chloride secretion and increased sodium absorption.
This results in lower osmolarity in mucus, causing it to become denser and harder to clear.
The thickness and density of mucus lead to trapped bacteria and ineffective pathogen clearance.

Symptoms of Cystic Fibrosis

Lung Symptoms: Characterized by mucus-obstructed airways leading to chronic bacterial infections and decreased lung capacity.
Gastrointestinal Symptoms: Blocked pancreatic ducts cause decreased enzyme production, leading to digestive issues and intestinal blockage.

Mucus Composition

Mucus is comprised mainly of mucins, high molecular weight glycoproteins that trap pathogens and dust.
The periciliary fluid serves as a medium for cilia and is essential for effective mucociliary transport; CF causes it to be abnormally thin.

CF Progression

The compromised function of CFTR results in a cascade of cellular changes: less chloride is secreted, increased sodium influx, leading to dense mucus that traps bacteria and causes lung infections.

Description

This quiz covers essential aspects of Cystic Fibrosis, including its genetic basis, lung function, and the role of the CFTR gene. You'll explore how mutations can lead to this autosomal recessive disorder and the implications for respiratory health. Test your knowledge on Mendelian and multifactorial traits as they relate to Cystic Fibrosis.