Primary Ciliary Dyskinesia Flashcards
A 16-year-old boy is evaluated for chronic cough and recurrent sinus infections. His parents report that he has had frequent upper respiratory infections since infancy, and his cough has progressively worsened over the years. Physical examination reveals bilateral crackles and clubbing. A chest X-ray shows dextrocardia and bronchiectasis. Nasal nitric oxide levels are low. A genetic mutation is identified affecting the dynein arms of cilia.
Which of the following is the most likely diagnosis?
A. Cystic fibrosis
B. Asthma with allergic bronchopulmonary aspergillosis
C. Primary ciliary dyskinesia (Kartagener syndrome)
D. Chronic granulomatous disease
E. Tuberculosis
Correct Answer: Primary ciliary dyskinesia (Kartagener syndrome)
Explanation: Primary ciliary dyskinesia (PCD) is an autosomal recessive disorder caused by defective ciliary structure and function, commonly due to dynein arm mutations. The defective ciliary movement leads to impaired mucociliary clearance, resulting in recurrent sinus infections, bronchiectasis, and chronic respiratory symptoms. Kartagener syndrome, a subtype of PCD, is characterized by the triad of situs inversus, chronic sinusitis, and bronchiectasis. The chest X-ray finding of dextrocardia, along with the history of recurrent infections and low nasal nitric oxide, strongly suggests this diagnosis.
Incorrect Answers:
A. Cystic fibrosis: While cystic fibrosis presents with recurrent respiratory infections and bronchiectasis, it is associated with pancreatic insufficiency, failure to thrive, and elevated sweat chloride levels, none of which are described here. B. Asthma with allergic bronchopulmonary aspergillosis: This condition presents with asthma symptoms, central bronchiectasis, and high serum IgE levels, which are not mentioned in this case. D. Chronic granulomatous disease: Recurrent infections occur due to defective phagocyte function, but this primarily involves catalase-positive organisms and does not explain situs inversus or low nasal nitric oxide. E. Tuberculosis: Tuberculosis typically presents with fever, weight loss, night sweats, and focal lung findings. The chronicity and situs inversus in this case are inconsistent with tuberculosis.
What is the genetic basis of Primary Ciliary Dyskinesia (PCD)?
Primary Ciliary Dyskinesia is an autosomal recessive disorder caused by mutations in genes responsible for ciliary structure and function, such as DNAH5 and DNAI1.
What is Kartagener syndrome?
Kartagener syndrome is a subset of Primary Ciliary Dyskinesia characterized by the triad of situs inversus, chronic sinusitis, and bronchiectasis.
What causes the symptoms in Primary Ciliary Dyskinesia?
Symptoms result from defective ciliary movement, leading to impaired mucociliary clearance and dysfunction of motile cilia.
What are the hallmark clinical features of Primary Ciliary Dyskinesia?
Features include recurrent respiratory infections, chronic sinusitis, otitis media, bronchiectasis, and infertility (due to immotile sperm or dysfunctional fallopian tube cilia).
What imaging finding is characteristic of Kartagener syndrome?
Chest imaging often reveals situs inversus (reversal of normal organ placement) in patients with Kartagener syndrome.
What tests are used to screen for Primary Ciliary Dyskinesia?
Diagnosis includes nasal nitric oxide measurement (low levels).
What tests are used for confirming Primary Ciliary Dyskinesia?
electron microscopy showing ciliary defects.
genetic testing for mutations in ciliary function genes.
What is the role of ciliary dysfunction in male and female infertility in Primary Ciliary Dyskinesia?
Ciliary dysfunction leads to immotile sperm in males and impaired movement of the ovum through the fallopian tubes in females, resulting in infertility.
What is the management strategy for Primary Ciliary Dyskinesia?
Management focuses on airway clearance techniques, regular chest physiotherapy, treatment of infections with antibiotics, and supportive care for respiratory symptoms.
Surgical intervention is needed for advanced disease.
What complications are associated with untreated Primary Ciliary Dyskinesia?
Complications include progressive bronchiectasis, chronic respiratory failure, and hearing loss due to recurrent otitis media.
How can Primary Ciliary Dyskinesia be differentiated from cystic fibrosis?
Unlike cystic fibrosis, Primary Ciliary Dyskinesia does not involve elevated sweat chloride levels or pancreatic insufficiency, and it may present with situs inversus.
