Primary ciliary dyskinesia is a genetic disorder in which impaired development and function of cilia leads to recurrent respiratory infections, hearing deficits and congenital heart malformations. Symptoms are present from birth, and the diagnosis is often missed, primarily because of the lack of clinical suspicion. Patient history, clinical criteria and a range of laboratory, as well as genetic tests, are used to confirm the diagnosis.
Primary ciliary dyskinesia (PCD) is a genetic disorder of abnormal ciliary function and/or structure, thus the signs and symptoms are related to their respective locations - the upper and lower respiratory tracts, the middle ear, and the reproductive tract    . Symptoms start shortly after birth, when the majority of patients suffer from recurrent bacterial infections of the paranasal sinuses and the lungs, as cilia are unable to perform their function of moving mucus and bacteria   . A wet cough, rhinorrhea, respiratory distress, tachypnea, hypoxia and the development of neonatal pneumonia are prominent symptoms   . Many reports have stressed that the diagnosis is frequently delayed until adulthood, despite the persistent presence of respiratory complaints and recurrent infections   . In addition, virtually all children (85-95%) suffer from a severe inflammation of the inner ear (otitis media) with effusion manifesting as conductive hearing impairment  . Ciliary dysfunction is also responsible for male infertility and female subfertility, due to the fact that cilia are pivotal for motility of the sperm and the function of the fallopian tubes, respectively    . Interestingly, about 50% of all individuals suffering from PCD are diagnosed with situs inversus, which arises because of the important roles of cilia in the formation of cardiac structures during embryogenesis, and often predisposes to a number of congenital heart diseases (CHDs)     . Other less common features are dextrocardia, heterotaxy (isomerism of the atrial appendages), hydrocephalus and atresia of the biliary tree .
Although prevalence rates estimate PCD to affect about 1 in 10,000-15,000 individuals, several studies have concluded that the condition is both underreported and underdiagnosed, thus assuming its more frequent in clinical practice   . For this reason, PCD must be included in the differential diagnosis of unexplained recurrent respiratory and otogenic symptoms, particularly in neonates. To establish a diagnosis, a detailed patient history and a complete physical examination are an absolute necessity. Apart from evaluating the onset and progression of symptoms, family history is of essential importance, keeping in mind the autosomal recessive pattern of inheritance (some reports also indicate an X-linked pattern)  . During the physical exam, sensorineural hearing loss and confirmation of respiratory complaints are noted, while cardiac auscultation may reveal situs inversus or dextrocardia, in which case additional studies should be performed to determine the underlying cause. Plain radiography and computed tomography (CT) are useful tools in PCD patients, as thickening of the bronchial wall, lung hyperinflation, and less commonly atelectasis and/or consolidation are typical signs  . To make a definite diagnosis, several specific tests are described in the literature     :