FAQ

The terminology surrounding genetic motile cilia defects can be confusing. There have been a number of changes that reflect an evolving understanding of what causes the symptoms in what is now called primary ciliary dyskinesia (PCD). With the explosion of information about motile cilia genetics in the past two decades, it is possible that the name will continue to evolve to more accurately reflect the underlying genetic/functional picture. For more information about the history of PCD and its terminology, click here.

Airway clearance therapy (ACT) is just what its name implies—therapies or activities designed to help clear mucus from the airway. ACT can be done in many ways. Hand-clapping (also called CPT for ‘chest physiotherapy’) and vest therapy are the two main forms used in CF and PCD, primarily because these conditions have the need for daily, comprehensive ACT and CPT and the vest are thought to be better at moving mucus from both the large and small airways (although no one knows if this is actually true). Acapella, Flutter, Quake and others are ACT devices in the category of ‘positive expiratory pressure’ or ‘PEP’devices. These devices are good for holding the airways open (or ‘stenting’ them) to facilitate clearance. Some of them vibrate the airways as well, which can help move mucus from smaller airways to larger one where it is easier to cough it out or swallow it. They can be used in combo with the vest and their stenting action can help airways remain open while the oscillation of the vest moves mucus. The last very important form of ACT is exercise. It’s a ‘two-fer,’ moving mucus and also naturally opening the airways.

Pulmonary function testing or PFTs (aka ‘spirometry’) is a surveillance technique that measures how effectively your lungs are performing by tracking the amount (volume) and speed (flow) of air being inhaled and exhaled. To perform PFTs, the patient is asked to blow into a mouthpiece while a computer records the force of the expelled air, how long it takes to fully empty the lungs and a number of other values that give an overall picture of lung function . The two values of most interest to doctors treating PCD are the FEV1 (forced expiratory volume in 1 second), which measures how effectively your lungs are able to expel a large volume of air in the first second of exhalation and FVC (forced vital capacity) which shows the total amount of time required to expel all air from the lungs.

PFTs have proven to be a very reliable tool for measuring and predicting disease progression in conditions like cystic fibrosis, asthma and COPD. Their utility in PCD is not as clear at this point, but the European Respiratory Task Force on PCD still recommends that PFTs be done every 3-6 months.

Please visit the ‘Find a Center‘ page to find a PCD clinical center near you.

There is no reliable demographic data to indicate the overall life expectancy for individuals with PCD. However, anecdotal reports indicate that in some people, PCD may be associated with a reduced lifespan due to chronic respiratory disease. This reduction is not as severe as that seen in cystic fibrosis, a similar disorder, and some individuals with PCD have lived into their seventh or eighth decade of life.

It is also important to note that number of years aside, PCD is associated with significant illness and quality of life deficits throughout the lifespan. This is why research that will lead to better diagnosis, treatments and cures are so critical for the population.

Chronic infections and progressive bronchiectasis can lead to severe lung disease for some patients with PCD. Because there currently are no cures or regenerative therapy options for PCD, treatment and management of severe lung disease in PCD is focused on managing symptoms, including aggressively treating infections (often requires IV medications and permanent venous access lines), using supplemental oxygen, and keeping the airways as clear as possible. If these measures are not sufficient and the patient progresses to respiratory failure, lung transplantation may be an option. Lung transplants have been successfully performed in PCD, even in individuals with situs anomalies.

It is also important to note that number of years aside, PCD is associated with significant illness and quality of life deficits throughout the lifespan. This is why research that will lead to better diagnosis, treatments and cures are so critical for the population.

Yes! Please visit the ‘CLEAN-PCD Trial‘ page for more information.

Research in PCD falls into two broad categories: 1) Basic science, and 2) Clinical research. Both are critically important in finding a cure for PCD. Basic science does not involve human beings, although it may rely on human tissue or cells. Clinical research refers to any type of study or trial that involves actual people. The PCD community has been so small and so geographically dispersed that it has been challenging to conduct clinical research—until now. By collaborating with PCD investigators and patient groups around the world, the international PCD community will now have the opportunity to participate in research aimed at better understanding the disorder (e.g. long term—or ‘longitudinal’ observational studies of the natural history of PCD), determining whether existing therapies used in other disorders will work for PCD (e.g. azithromycin trial in Europe), identifying potential new therapies (e.g. CLEAN-PCD trial in North America and Europe). With a growing patient community and growing interest on the part of researchers and drug developers, we anticipate that there will be many other research opportunities in the near future.

Having a verified diagnosis, especially knowing your genetics, will be very important in PCD research trials going forward. It is also important to note that number of years aside, PCD is associated with significant illness and quality of life deficits throughout the lifespan. This is why research that will lead to better diagnosis, treatments and cures are so critical for the population.

According to the World Health Organization, antibiotic resistance occurs when bacteria change in response to the use of antibiotics, which are medicines used to prevent and treat bacterial infections (WHO). Specifically, bacteria change by developing defenses that help them ‘resist’ – or survive – exposure to certain antibiotics, making antibiotic therapy to treat infection more challenging.

Per the American Lung Association, bronchiectasis is a chronic condition where the walls of the bronchi are thickened from inflammation and infection. People with bronchiectasis have periodic flare-ups of breathing difficulties, called exacerbations (ALA). Over time, chronic infection in the airways damages the airway wall, scarring it, making it thicker and/or stretching it (called dilation). These damaged areas become a reservoir for excess mucus that provides a breeding ground for more bacterial infection.

A common airway pathogen in PCD is Pseudomonas aeruginosa (Pa), and the prevalence of this bacteria increases with age. Pseudomonas infection is caused by strains of bacteria found widely in the environment; the most common type causing infections in humans is called Pseudomonas aeruginosa (CDC). While treatment guidelines have not been established, it is understood that Pa infection can be associated with lung function deterioration and aggressive treatment is often, but not always, recommended. For newly acquired infection, the focus is often on eradication. With chronic infection, however, the aim is to preserve lung function and stabilize the patient. Clinical trials targeting Pa therapies are needed in the PCD population to help determine guidelines for treatment.

Individuals with chronic airway infections and bronchiectasis often harbor harmful bacteria in their sputum. This infected sputum becomes a breeding ground for increasingly challenging and serious bacterial infections. ‘Surveillance culture’ refers to the practice of routinely assessing sputum cultures in at-risk individuals to monitor bacterial growth over time. This is different than cultures done when ill. Surveillance cultures are collected on a scheduled basis (often quarterly, every six months, or annually) when the person is at baseline health.

There are currently 44 identified genes (each with many different variants/mutations) known to be associated with PCD. In PCD, variants/mutations that affect the ability of these genes to perform their necessary function are what result in expression of the disorder. In contrast, there is only a single gene associated with cystic fibrosis. More than 2,000 variants have been identified on CFTR, and about 200 of those result in cystic fibrosis. Even in CF, a disorder caused by variants on a single gene, there is a significant spectrum of disease expression. This is because different variants on the same gene may cause different levels of gene dysfunction. Some variants produce complete loss of function. Some produce milder loss of function.

In PCD, the picture is much more complex. First, we have more genes, some of them much larger than the CF gene, and we do not even have a clear picture of how many variants may be on each gene. Because there are so many genes involved, we also have different forms of inheritance depending on gene, and a complex picture of variants by gene.

There is limited data demonstrating that some genes involved in PCD may result in more or less severe disease, so the gene involved may be one explanation for why someone with PCD is sicker or healthier. But that is not the complete picture. The specific type of variant on any gene may also contribute to overall severity. Additionally, non-PCD-related genes may also contribute to disease severity. Sometimes other genes may provide additional function that makes up for the loss of function in PCD, resulting in milder disease (*please note—this has been demonstrated in CF, but not in PCD yet so we don’t really know if this happens). Sometimes, other individual genetic factors contribute to worse disease expression.

Finally, individual environmental exposures may affect outcomes, producing either milder or worse disease expression.

It is common in children with cystic fibrosis (and PCD) to culture Pseudomonas aeruginosa (Pa), a pathogen that infects the lower airways. This bug is often treated with inhaled antipseudomonal antibiotics, such as tobramycin inhalation solution (TIS). TIS treatment has proven effective in clearing Pa in children, but the risk of recurring Pa growth and subsequent pulmonary infections remains high. The OPTIMIZE trial was conducted to determine if the addition of azithromycin to inhaled tobramycin in children with CF and new isolation of Pseudomonas aeruginosa would decrease the risk of pulmonary exacerbation and prolong the time to reoccurrence. While not considered the most effective treatment for pathogens like Pa, azithromycin has been noted for its anti-inflammatory properties. When used prophylactically (not as a treatment for a specific infection), it is given at a reduced dosage on an ongoing basis.

Infertility and sub-fertility are common manifestations of PCD. Male infertility used to be considered universal, but there are reports of male PCD patients with normal reproductive capabilities. Females may experience sub-fertility and/or an increased risk for ectopic (tubal) pregnancy. Many women with PCD have achieved pregnancy naturally, however. For family planning purposes, it is important not to assume you will be infertile just because you have PCD!

Subfertility in PCD is a mechanical issue—a matter of being unable to get the necessary reproductive components where they need to be. This should be distinguished from ‘sterility,’ which implies that the components themselves are not viable. Because most people with PCD have sperm and egg cells that are perfectly fine, just unable to travel due to ciliary inactivity, IVF, ICSI and other assisted reproductive services have been used with a high level of success in PCD.

A person with PCD has two ‘bad’ copies of a PCD gene. Thus, they have no ‘good’ copy to pass on. All of their children will inherit one of these mutated copies, so all will be a PCD carrier. If the other parent is also a carrier (has one copy with a pathogenic PCD mutation ON THE SAME PCD GENE AS THE PCD PARENT), there is a 50/50 chance that the child will inherit the bad copy from the carrier parent. Since the PCD parent only has bad copies to contribute, the child will inherit two bad copies and have PCD. However, this is only an issue if the carrier parent’s pathogenic mutation is on the same gene as the PCD parent. The odds of this, while not impossible, tend to be very, very low given how rare PCD is. There are actually no documented incidences of this occurring to date outside of communities that practice familial intermarriage.

So all children of a PCD parent will be PCD carriers. Under certain conditions, if a PCD parent and a PCD-carrier parent have children, there is a 50/50 chance a child could be born with PCD, but this is a very rare occurrence.

PCD is a progressive lung disease and the focus of treatment is to delay the acquisition of bronchiectasis for as long as possible, and to slow down progression of lung damage once bronchiectasis has occurred. Even best efforts with appropriate, aggressive treatment are not always successful with these goals and progressive worsening of lung disease can lead to advanced lung disease and respiratory failure. When this occurs, lung transplantation may be an option for individuals with PCD. Because of the infections seen in PCD, patients should only consider double lung transplant. This is true of cystic fibrosis, non-CF bronchiectasis, and other conditions characterized by serious infections.

The decision to proceed to transplant is not easy and should be undertaken with a trusted medical adviser. Transplant is a process and certain conditions must be met before an individual is even eligible to be worked up or listed for transplant. There are fewer lungs available for transplant than there are people who need them, so allocation of organs is based on a scoring system designed to ensure that available lungs are used in a way that is most likely to be successful. This means that some people will not get lungs and every effort should be made to avoid getting to the point where transplant is required.

There have been roughly 3,000 confirmed diagnoses of PCD in North America, however, delayed or missed diagnosis is quite common with this disease and there could be upwards of 25,000 people who are affected and don’t know it. This not only speaks to how difficult it can be to get a diagnosis of PCD, but also why the PCDF Clinical & Research Centers are so important.

Please visit the ‘Diagnosis‘ page to learn what diagnostic tools are used in PCD.

Per the 2015 consensus statement, high-speed videomicroscopy, which is an examination of cilia waveform from a ciliary biopsy, can be sufficient in providing a clinical diagnosis for PCD. However, there is a caveat: this test must be performed by a qualified medical professional who has experience with high speed videomicroscopy technology. If this test is performed by a medical technician who is not an expert, there is a chance of either a false-negatives or a false-positive result, both of which can potentially be harmful to the patient.

For reasons not yet known, the vast majority of individuals with PCD have very low levels of a gas called nitric oxide (not ‘nitrous’) in their sinus cavities. This is not just a small difference, it is a marked and significantly lower level than seen in people without PCD.* Because this finding has been verified in numerous studies around the world, measuring the nasal nitric oxide (nNO) level in individuals thought to have PCD can be a useful screening tool to help a physician decide whether or not PCD is a likely diagnosis. In the US, nNO testing cannot be used to make the diagnosis; nor can it be used to exclude PCD. It is a screening test only that will help prioritize decisions about next diagnostic steps. For more information about nNO screening, or other diagnostic tests for PCD, please visit ‘Diagnosing PCD.’

PCD diagnosis continues to be challenging. All current testing options available to aid in PCD diagnosis (biopsy with TEM, nasal nitric oxide measurement, high-speed videomicroscopy, immunofluorescent assay of ciliary proteins) have limitations and do not work in all cases of PCD. Genetic testing is getting better all the time, but it is not widely available in all areas and, even where it is available, it can be difficult to get insurance coverage for it. Also, we have not yet identified all the genes associated with PCD, so while the gene testing panels are far more comprehensive now than in the past, they still are incomplete. A PCD genetic test can positively make the diagnosis if known mutations are found. But a negative PCD genetic test does not rule out PCD. It just rules out PCD caused by genes/mutations evaluated on the specific panel.

Read more about symptoms and diagnosis in this blog post by PCDF Executive Director Michele Manion.

Respiratory epithelial biopsy with Transmission Electron Microscopy (TEM) processing for ultrastructural examination of ciliary axonemes is a proven technique for PCD diagnosis and is recommended as part of a panel of diagnostic tests for PCD. Disease-causing TEM defects in the outer dynein arms, outer and inner dynein arms, inner dynein arms with microtubule disorganization, radial spokes, or central apparatus provide confirmation of PCD diagnosis. However, TEM studies with normal ciliary ultrastructure do not rule out PCD, as certain PCD gene mutations can result in normal ultrastructure, or subtle abnormalities (particularly those involving the central apparatus and radial spokes) that are not readily recognized on TEM (PCDF Consensus Statement).

When performed by experienced technologists and analyzed by pathologists familiar with ciliary defects, TEM can yield usable diagnostic results in about 70% of cases. In reality, however, this ‘ideal’ situation is very rare and the yield of reliable results is much lower at most centers. Therefore, the PCD Foundation recommends that all patients with suspected PCD be directed to PCD Foundation Clinical and Research Network Centers for TEM as part of a larger PCD diagnostic workup.

According to the PCDF Consensus Statement, “Genetic testing for disease-causing mutations associated with PCD is recommended as part of a panel of diagnostic PCD tests.” There are currently 44 known genes associated with PCD, which counts for an estimated 75% of patients who have this disease. Ultimately, the goal is to provide therapies targeted at specific genes, so a confirmed PCD diagnosis via a genetic panel will be increasingly important.

When the diagnosis of PCD cannot be confirmed, PCD Clinical Centers use the designations of ‘probable’ or ‘possible’ to clarify the status with regard to PCD diagnosis. These designations recognize that it is simply not possible to confirm all cases of PCD right now and allow for aggressive treatment of the underlying condition, while still acknowledging that additional confirmatory PCD testing or consideration of non-PCD causes may be required in the future.

The PCDF consensus recommendations states that “many physicians incorrectly diagnose PCD or eliminate PCD from their differential diagnosis due to inexperience with diagnostic testing methods. Thus far, all therapies used for PCD are unproven through large clinical trials.” The statement continues: “patients often receive false-positive or false-negative PCD diagnoses, as physicians are unaware of the pitfalls commonly encountered with ciliary electron microscopy, PCD molecular genetic panels, ciliary motility studies, and nasal nitric oxide testing.”

Although gene-specific therapies are not available at this time, it is important to confirm (or rule out) a PCD diagnosis so that patients can be on an optimal treatment regimen to manage their disease. Therefore, it is critical that all diagnostic tests are performed by experienced technicians, preferably at one of our many PCDF Clinical Centers located all across the U.S. and Canada.

In the 1970’s, a Swedish electron microscopist named Bjorn Afzelius was analyzing sperm of infertile men and notice that a subset of them also had bronchiectasis and sinus issues and that about 50% of this subset also had situs inversus–the so-called Kartagener syndrome. He was intrigued that only about half of these patients, actually had the hallmark symptom of Kartagener triad–situs inversus–though.

These patients looked identical in all respects, except the situs issue. Because he had noted distinct changes in the internal ultrastructure of the cilia of these patients, he theorized (and turned out to be correct) that all their symptoms–infertility, respiratory disease and situs inversus–were caused by a single factor–underlying ciliary defects–and that situs inversus was, in fact, just a random manifestation of this dysfunction (correct again). Because microscopes of that time were not particularly sensitive, ciliated samples from these patients appeared to be completely immotile, so he called this ‘immotile cilia syndrome,’ a name that stuck for decades. This was progress and we were getting closer to the underlying cause, but it was still a syndromic diagnosis based on observation.

‘Kartagener syndrome,’ is an older term commonly used to describe PCD with situs inversus. Since this presentation of PCD is just one of three possible organ placements, the term ‘Kartagener’s’ is somewhat limiting. Nevertheless, it persists because it has been in the medical literature for over a century. Individuals with PCD and situs solitus or PCD with situs ambiguus do not have ‘Kartagener syndrome’ as the term is only used for PCD with situs inversus. For more information on the terms used to describe PCD, please check out ‘What’s in a Name? A Brief History of PCD Terminology.’

PCD is a genetically heterogeneous, autosomal recessive disorder characterized by motile cilia dysfunction (ATS Diagnostic Guidelines). An autosomal recessive disorder means two copies of an abnormal gene must be present in order for the disease or trait to develop. You inherit two mutated genes, one from each parent. These disorders are usually passed on by two carriers.

Motile cilia are microscopic, whip-like organelles (little organs) that line the upper and lower respiratory tract including nasal passages, sinuses and lung, and eustachian tubes of the ear, the reproductive organs, and the ventricles of the brain. The activity of motile (moving) cilia, working in cooperation with airway mucus, provides a first line of defense for the airways, maintaining healthy airway tissue. This important biological system is known as ‘mucociliary clearance.’ Defects of mucociliary clearance can lead to profound illness. Cystic fibrosis is an example of another devastating genetic disorder of mucociliary clearance that shares many features with PCD.

‘Laterality’ is a term describing the dominance or difference between the sides of the body. The body is not identical on both sides (called ‘asymmetry’), and the process by which the body knows how to organize laterality/asymmetry is very complex. One important factor appears to be the motion of unique cilia on the embryonic node (called ‘nodal cilia’) which only appear once in our life. The activity of these unique motile cilia plays an important role in determining the placement of organs within the thoracic and abdominal cavities. In the absence of this ciliary motion, organ placement becomes a random event, giving each affected embryo a 50/50 chance of having typical placement (known as situs solitus), mirror-image placement with reversed organs (known as situs inversus) or an unusual pattern of unique organ development or placement (situs ambiguous or heterotaxy). Many PCD genetic mutations also impact the motility of the nodal cilia. With these mutations, approximately 50% of PCD patients present with situs solitus and the remaining patient population having either situs inversus or situs ambiguus (‘ambiguous’)/heterotaxy.

In addition to lung, ear & sinus disease, genetic defects that cause PCD can affect all areas that rely on ciliary motility, including reproductive organs (sperm tails in males and fallopian tubes in females) and ventricles of the brain (rare reports of ventriculomegaly or hydrocephalus). It is important to note that not all individuals with PCD will have issues with infertility or subfertility and that motile cilia dysfunction and brain/central nervous system disorders appear to be very rare in humans. There are isolated reports of other associated disorders in PCD which are currently being investigated.

Gastric issues and headaches have been reported by many people with PCD. Of note, THERE ARE NO MOTILE CILIA IN THE GI TRACT. Microvilli found in the GI tract look like cilia, but they are structurally and genetically different. There are primary/sensory cilia in the GI tract, but their role, if any, in the GI complaints seen in PCD is not currently known. Headaches that are not sinus in nature are also a common complaint in PCD and the possible reasons for these headaches are currently being explored.

Although there is no specific data on the effects of exercise as it relates to PCD, we encourage all patients to be active within their own physical limitations. Please visit ‘Living with PCD‘ for more information.

One of the most important things you can do to help your child with PCD get the most from school is to educate his/her teacher about the disorder. Here is a sample letter you can use with your child’s teachers and other school officials. Feel free to adapt for your personal use. For more information, click here.

Please visit our ‘PCD at School‘ page to learn more about an Individualized Education Program (IEP).

Many people with PCD pursue fulfilling careers and are able to support themselves through employment. However, some are not, and the chronic infections and daily therapies required to maintain health in PCD can make full-time employment difficult to manage. As PCD lung disease progresses it may be necessary to consider disability. Parents of children with PCD can experience excessive missed work days for issues related to their children’s health, as well. For more information, click here.

Insurance companies in the US use the International Classification of Disease (ICD) coding system for coding diseases. These codes are published by the World Health Organization (WHO) and are consistent around the world. Unfortunately, WHO has not been particularly good at assigning codes to rare disorders and the majority of rare diseases do not have a specific code. PCD is one of these disorders.

The current version of the ICD codes used in the US is ICD 10. ICD 11 is in use in other parts of the world and offers the opportunity to petition for a diagnostic code. There is an international effort to get a code for PCD and other motile ciliopathies and we are optimistic there will be a PCD code in 2020/2021.

Unfortunately, we do not provide direct funding at this time.