PRIMARY CILIARY DYSKINESIA (PCD)
PRIMARY CILIARY DYSKINESIA (PCD) DEFINITION
Primary ciliary dyskinesia (PCD) is a rare genetic (inherited) condition that can lead to chronic ear, sinus, pulmonary disease (bronchitis/bronchiectasis), reversed or flipped organs (situsinversus) and fertility issues.
PRIMARY CILIARY DYSKINESIA (PCD) CAUSES
Primary ciliary dyskinesia (PCD) is a rare, inherited disease. “Inherited” means the disease is passed from parents to children through genes. With PCD, this process is very complex. Researchers are still learning how the disease is inherited and which genes are involved.
Generally, a child must inherit faulty genes from both parents to have PCD. These genes affect how cilia grow and function. Cilia are tiny, hair-like structures that line the airways.
The airways include your nose and linked air passages; mouth; larynx (LAR-ingks), or voice box; trachea (TRA-ke-ah), or windpipe; and tubes called bronchial tubes or bronchi, and their branches.
Cilia move mucus (a slimy substance) through your airways and toward your mouth to be coughed or sneezed out of your body. The mucus contains inhaled dust, bacteria, and other small particles.
Faulty genes may cause the cilia to be the wrong size or shape or move in the wrong way. Sometimes the cilia are missing altogether. If the cilia don’t work well, bacteria stay in your airways. This can cause breathing problems, infections, and other disorders.
PRIMARY CILIARY DYSKINESIA (PCD) PATHOPHYSIOLOGY
Defects in the ciliary component cause abnormal ciliary movements, resulting in impaired mucociliary clearance and manifesting as recurrent and or persistent sinopulmonary infections, among other problems.
Dynein arm defects manifest as a total or a partial absence of either both inner or both outer dynein arms or involve just the inner or outer arms. Sometimes, shortened dynein arms are the only defect. Recent studies show differential functions of both inner and outer dynein arms and correlate ciliary beat frequency directly with the number of outer dynein arms. The ciliary beat frequency is not correlated with the number of inner dynein arms.
Radial spoke defects exhibit either a total absence of radial spokes or an absence of radial spoke heads. These defects are easily recognized by an eccentric position of the central pair of microtubules that are normally stabilized in a central position by radial spokes. Microtubular transposition defects occur in the form of absence of the central pair of tubules with transposition of the outer doublet to the center. Other defects, such as ciliary aplasia, ciliary disorientation, malaligned central pair of microtubules in adjacent cilia, and basal body abnormalities may occur after viral infections, making it unclear if they are primary or secondary defects.
PRIMARY CILIARY DYSKINESIA (PCD) SYMPTOMS
Primary ciliary dyskinesia (PCD) mainly affects the sinuses, ears, and lungs. One sign that you might have PCD is if you have chronic (ongoing) infections in one or more of these areas. Common signs, symptoms, and complications linked to PCD include the following:
o Chronic nasal congestion
o Runny nose with mucus and pus discharge
o Chronic sinus infections
o Chronic middle ear infections
o Hearing loss
o Respiratory distress (breathing problems) in newborns
o Chronic cough
o Recurrent pneumonia
o Collapse of part or all of a lung
PCD also can cause fertility problems in men and women. “Fertility” refers to the ability to have children. In men, PCD can affect cilia-like structures that help sperm cells move. Because the sperm cells don’t move well, men who have the disease usually are unable to father children.
Fertility problems also occur in some women who have PCD. These problems likely are due to faulty cilia in the fallopian tubes. (The fallopian tubes carry eggs from the ovaries to the uterus.)
About half of all people who have PCD have Kartagener’s syndrome. This syndrome involves three disorders: chronic sinusitis (si-nu-SI-tis), bronchiectasis (brong-ke-EK-tah-sis), and situsinversus.
Chronic sinusitis is a condition in which the sinuses are infected or inflamed. The sinuses are hollow air spaces around the nasal passages.
Bronchiectasis is a condition in which damage to the airways causes them to widen and become flabby and scarred.
Situsinversus is a condition in which the internal organs (for example, the heart, stomach, spleen, liver, and gallbladder) are in opposite positions from where they normally are.
Situsinversus can occur without PCD. In fact, only 25 percent of people who have the condition also have PCD. By itself, situsinversus may not affect your health. However, in PCD, it’s a sign of Kartagener’s syndrome.
Some people who have PCD have abnormally placed organs and congenital heart defects.
PRIMARY CILIARY DYSKINESIA (PCD) DIAGNOSIS
For patients and parents, early clues to diagnosis include respiratory problems that begin at birth or within the first few months of life. Daily (or very frequent) cough is present, often wet-sounding. Drainage from and/or plugging of ears and constant ‘drippy’ nose are common complaints. Noisy breathing and the production of lots of sputum can lead to a misdiagnosis of asthma. Failure to respond to typical asthma treatments is often reported. Recurring bouts of bronchitis or pneumonia, sometimes with unusual organisms causing the infections, are typical.
Many families also report frequent headaches, both sinus-related and non-sinus related, stomach and GI complaints, failure to gain weight and unusual fevers, although these are not known to be specifically relate to PCD at this time.
Official diagnostic criteria are listed here: Adapted FromGeneReviews Primary Ciliary Dyskinesia
MAKING THE DIAGNOSIS
The diagnosis of primary ciliary dyskinesia (PCD) requires the presence of one or more of the following:
Chronic sinopulmonary (sinus, ear and lung) disease:
- Chronic cough (often wet sounding) and sputum production
- Chronic wheeze and air trapping
- Obstructive lung disease on lung function tests Persistent colonization with pathogens (bugs that cause infection) not commonly found in healthy individuals, like Pseudomonas aeruginosa, Staphylococcus aureas and Haemophilus influenza
- Chest x-ray or other imaging studies with chronic abnormalities
- Sinus x-ray or other imaging studies with chronic abnormalities
- Chronic otitis media (ear fluid/infection)
- Neonatal respiratory distress (can be mild or very severe)
- Chronic nasal congestion dating from the newborn period
Abnormality in chest and abdominal organ placement, which may manifest as:
- Situsinversustotalis or mirror-image reversal of all internal organs, with all organs typically functioning just fine in their mirror image position, or
- Situs ambiguous, aka ‘heterotaxy’ a condition characterized by the abnormal placement of organs due to failure to establish the normal left-right patterning during embryonic development (Medicinet.com definition). Heterotaxy is often associated with congenital defects of one or more organs and is especially associated with congenital heart defects which may be mild and manageable or complex and severe.
- Digital clubbing – a condition in which the ends of the fingers around the nail beds become swollen and rounded. The nails may take on a shiny, abnormally curved appearance. Here is a picture of digital clubbing in a child with cystic fibrosis:
- Specific ciliaryultrastructural defects identified by transmission electron microscopy or ‘TEM.’ This “gold standard” diagnostic test for primary ciliary dyskinesia requires a biopsy of ciliated airway tissue usually taken by brush sample or scraping of either the nose or the trachea. More information on the biopsy process and challenges with diagnosis in PCD
- Positive Clinical genetic testing for PCD. More information on Genetic Testing for PCD
- In addition, measurement of nasal nitric oxide (NO), while not diagnostic, can be a very useful screening tool in PCD, which is characterized by unusually low levels of nasal NO. More information on Nasal Nitric Oxide in PCD
PRIMARY CILIARY DYSKINESIA (PCD) TREATMENT
Unfortunately, no treatment is available yet to fix faulty airway cilia. (Cilia are tiny, hair-like structures that line the airways.) Thus, treatment for primary ciliary dyskinesia (PCD) focuses on which symptoms and complications you have.
The main goals of treating PCD are to:
- Control and treat lung, sinus, and ear infections
- Remove trapped mucus from the lungs and airways