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What is Primary Ciliary Dyskinesia (PCD)?

Primary Ciliary Dyskinesia (PCD)

also called

Immotile Cilia Syndrome

is a rare, congenital (by birth), genetic lung condition in which the patients experience chronic (long lasting) respiratory tract infections, infertility or inability to have children and abnormally positioned internal organs. In this condition which affects 1 in 16000 people, tiny, hair-like structures known as cilia that move the mucus out of the airways in the respiratory tract are either immobile or abnormal. Thus, PCD means,

Primary = something that is inherited (not from outside), Ciliary = cilia or the vibrating hairs, Dyskinesia = disordered motility (movement) or badly moving.

In people suffering from

PCD,

the cilia may not develop (ciliary aplasia), move ineffectively or inadequately (dyskinetic cilia) or may be completely paralyzed (immotile cilia).

Before getting to know more about this disorder, let’s gain some knowledge on cilia and their significance.

Cilia – Their importance:

Cilia - cross section shows evidence of immotile cilia syndrome

Did you know that the respiratory system which includes ears, nose, pharynx and sinuses (upper respiratory parts), and lungs, bronchi, bronchioles, respiratory muscles and alveoli (lower respiratory parts) requires the coordination of several billions of cilia to stay healthy? Yes, it is true indeed! These microscopic, finger-like projections that stick out from the surface of cells are found lining the airways of the respiratory tract, reproductive system and some other organs.

Cilia in respiratory tract –

With coordinated back and forth movements, these tiny projections move the mucus from lungs towards throat. Through mucus, bacteria, fluid, dust and unwanted particles are eliminated from the body through cough. If the cilia do not function properly as seen in

Immotile Cilia Syndrome,

the bacteria remain in the airways and cause recurring respiratory infections. In addition, the accumulated mucus also causes infections and blockages. These chronic respiratory infections may in turn lead to bronchiectasis, a condition in which the passage from trachea (windpipe as it is called) to bronchi of the lungs is severely damaged causing breathing problems that can be life threatening.

Flagellae –

Apart from cilia, flagellae or tail-like structures that help in propelling the sperms towards egg are also affected in this condition. In order for the sperms to move towards the egg, flagellae have to move vigorously. Due to slow sperm movement, men with

PCD

face problems in fathering children. Women in whom the cilia are abnormal in their fallopian tubes (a part of the reproductive system), infertility may occur.

Characteristic Features of Primary Ciliary Dyskinesia:

  • Respiratory distress or coughing, choking, gagging and lung collapse soon after the birth.
  • Frequent respiratory tract infections that begin in early childhood.
  • Chronic cough and nasal congestion throughout the year

    irrespective of the season.

  • Hydrocephalus or accumulation of fluid in the brain.
  • Recurring ear infections also known as otitis media. Young children with this condition may experience permanent hearing loss if not treated in its early stages.
  • Bronchitis and pneumonia.
  • Hearing loss or impairment.
  • Sinus infections.
  • Persistent flu symptoms

    such as coughing and sneezing.

  • Excessive mucus formation and difficulty in clearing it.
  • Infections do not respond to common antibiotics such as penicillin.

Conditions associated with Primary Ciliary Dyskinesia:

Individuals suffering from this condition may also have some other abnormalities. These include:

Situs Ambiguus or Heterotaxy –

Nearly 6% of the population with

PCD

have this condition which is

characterized by abnormalities of the liver, heart, spleen and intestines.

During embryonic development, problems in establishing the right and left sides of the body results in situs ambiguus. Moreover, the severity of the condition also varies from individual to individual. Some patients may not have a spleen at all (asplenia) or some may have many spleens (polysplenia).

Axial CT image showing situs inversus (liver on the left, spleen and aorta on the right) in a patient with Kartagener syndrome.

Situs Inversus Totalis –

This term describes the abnormal placement of the organs or mirror image reversal of the organs within the chest and abdomen.

Vital organs within the chest and abdomen are positioned on the other side of the abdomen.

For example, the heart is positioned on the right side of the body instead of left. Such patients are said to have Kartagener syndrome (KS). In some people, the organ function is not affected in spite of the change of the position, but in some serious defects have been reported. Almost 50% of the patients with

PCD

have this condition.

Genes & Inheritance of Primary Ciliary Dyskinesia:

Research studies have suggested that

mutations (permanent changes in the DNA) in at least 9 genes are responsible for this condition. These genes are responsible for the production of proteins that form the inner structure of cilia and also produce the force required for the cilia to bend.

The coordinated movement of cilia is an essential act for the normal functioning of the organs in which they are present. Moreover, during embryonic development, the ciliary movement helps in establishing the left-right axis or the imaginary line that separates the right and left sides of the body.

In almost 38% of people suffering from

PCD,

mutations in DNAH5 and DNAI1 were found. In most of the people the cause of the condition is not known.

Inheritance pattern –

Children inherit this condition from their parents in an autosomal recessive mode of inheritance, which means that both the gene copies in each cell are mutated. Parents act as carriers of the gene meaning they do not show any symptoms of the condition but carry one copy each of the mutated gene and pass it on to their children.

Diagnosing Primary Ciliary Dyskinesia:

The symptoms of this condition make it difficult for the doctors to diagnose the disorder exactly. The symptoms associated with

PCD

are commonly seen in some other diseases. That’s the reason why doctors often misdiagnose the condition as cystic fibrosis or atypical asthma.

Diagnosis usually involves:

  • Patient’s medical history.
  • This is followed by connecting the symptoms together as experienced by the patient.
  • Improper positioning of the vital organs such as heart, which is an indication of Kartagener Syndrome and PCD also helps in proper diagnosis.
  • Lung tissue biopsy helps in confirming the diagnosis.
  • A screening diagnostic test that measures the amount of nitric oxide in the nose is under development.
  • Research is being carried out to identify all the genes responsible for the condition. Once this is achieved, genetic testing that makes the diagnosis easy will be developed.

Delayed diagnosis can lead to:

  • Bronchiectasis.
  • Lung transplantation.
  • Repeated surgical intervention.

Treating Primary Ciliary Dyskinesia:

Treatments associated with any long-lasting lung disorder are usually aimed at maintaining the health of the unaffected tissue. Because there is no cure for this condition, survival of the patient can be extended if diagnosed at an early stage and necessary treatment is provided. Treatment options include:

  • Regular suctioning and washing of the ear canals and sinus cavities to keep the upper airways free from mucus accumulation.
  • Mucus thinners or mucolytics, bronchodilators and steroids are the medications used in treating the condition.
  • Use of intravenous, oral and inhaled antibiotics on a regular basis is advised by the doctors. Accumulated mucus in the airways aids in the rapid growth of bacteria. Therefore, antibiotics are used to get rid of them.

Preventing this condition from affecting our bodies is not possible. The severity is to such an extent that individuals dying in their early infancy or in utero have been recorded.

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