Cystic Fibrosis Notes

Cystic Fibrosis Overview

  • Cystic fibrosis is a genetic disorder causing severe damage to the digestive and respiratory systems.
  • It affects cells producing sweat, mucus, and digestive enzymes, leading to abnormal secretions.
  • Characterized by thick, sticky mucus buildup that damages organs.

Normal vs. Cystic Fibrosis Secretions

  • Normal Secretions: Thin and slippery, lubricating organs and tissues, preventing dryness and infection.
  • Cystic Fibrosis Secretions: Thick and sticky, clogging tubes, ducts, and passageways.

Effects of Thick Mucus

  • Lungs:
    • Blocks airways, promoting bacterial growth.
    • Leads to lung infections and severe lung damage over time.
  • Pancreas:
    • Blocks tubes, hindering digestive enzyme delivery to the small intestine.
    • Causes malnutrition and vitamin deficiency.
  • Sweat:
    • Becomes very salty, leading to excessive salt loss.
    • Upsets mineral balance, potentially causing dehydration, decreased blood pressure, stroke, and rarely, death.

Affected Organs and Systems

  • Primarily affects the lungs, pancreas, liver, and intestines.
  • Can also impact the kidneys and sex organs.
  • Causes infertility in both men and women.

Prevalence

  • Most common among white people of Northern European ancestry.
  • Least common among Africans and Asians.
  • Approximately 1,000 new cases diagnosed each year.
  • Most common inherited disease among white people.

Genetic Basis

  • Caused by a defect in the cystic fibrosis transmembrane conductance regulator (CFTR) gene.
  • CFTR gene is located on chromosome 7.
  • The gene makes a protein that regulates the movement of water and salt in and out of cells.
  • Every individual inherits two CFTR genes, one from each parent.

Inheritance Pattern

  • To have cystic fibrosis, a child must inherit a faulty gene from each parent.
  • Children inheriting one normal and one faulty gene are carriers, typically without developing cystic fibrosis but can pass the gene to their children.

Symptoms

  • Symptoms vary depending on severity.
  • Respiratory Symptoms:
    • Wheezing.
    • Breathlessness.
    • Persistent cough producing thick mucus.
    • Inflamed nasal passages or stuffy nose.
  • Digestive Symptoms:
    • Severe constipation.
    • Foul-smelling, greasy stools.
    • Poor weight gain and growth (especially in children).
    • Intestinal blockages, particularly in newborns.

Diagnosis

  • Newborn screening is routine in every state in the United States.
    • Early diagnosis within the first month of life, even before symptoms appear.
  • Newborn Screening Tests:
    • Blood test to check for higher concentration of immunoreactive trypsinogen (IRT), a chemical released by the pancreas.
    • Genetic test to identify the faulty CFTR gene.
  • Sweat Test:
    • Performed when the infant is at least 2 weeks old.
    • A sweat-producing chemical is applied to the skin.
    • Sweat is collected and analyzed for high salt levels.
    • High salt levels confirm the diagnosis.
  • Older Children and Adults:
    • Genetic tests may be recommended.
  • Prenatal Screening:
    • Amniocentesis and chorionic villus sampling can check if the fetus has the disorder.
  • Carrier Screening:
    • Recommended if planning a pregnancy and the partner has cystic fibrosis.
    • Checks whether you are a cystic fibrosis carrier.

Treatment

  • No cure exists; treatment focuses on easing symptoms and reducing complications.
  • Goals:
    • Prevent and control lung infections.
    • Loosen mucus in the lungs.
    • Treat and prevent intestinal blockages.
    • Provide adequate nutrition.
    • Prevent dehydration.
  • Treatment Methods:
    • Medications.
    • Chest physical therapy.
    • Surgical procedures.
    • Exercises.
    • Pulmonary rehabilitation.

Historical Context and Prognosis

  • Historically, children with cystic fibrosis rarely lived beyond their teens.
  • With advances in treatment, patients are now living longer.