Diagnosis and Treatment for PCD

No definitive test or treatment exists for PCD.3 More than 70% of patients with PCD have biallelic mutations in one of the 40 genes associated with the disease.3 By identifying the biallelic pathogenic variants in a PCD-linked gene, clinicians can diagnose PCD definitively.3 In the absence of treatments that repair cilia function, clinicians need to instruct patients on techniques to clear their airways to promote mucociliary clearance and administer antibiotics to prevent exacerbations of pulmonary symptoms.3


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“Patients with PCD have characteristic clinical features that distinguish [PCD] from other respiratory conditions of childhood, and diagnostic testing should be considered only in those who have a compatible clinical phenotype,” said Thomas W Ferkol, MD, Division of Pediatric Allergy, Immunology, and Pulmonary Medicine at Washington University School of Medicine, St. Louis, Missouri, in an email interview with Pulmonology Advisor.4

Dr Ferkol advised clinicians who do not often see PCD to keep in mind:

  • Although transmission electron microscopy has long been considered the diagnostic gold standard, this technique has limitations. The lack of ciliary defects does not exclude the diagnosis because 30% of patients who have PCD will have normal axonemal ultrastructure.
  • Genetic testing has become a useful diagnostic tool, with >40 genes now associated with the disease. [More than] 70% of patients with PCD who are tested have biallelic mutations in one of these genes, and this number will rise with further gene discovery.
  • Genotype-phenotype relationships are emerging, which are revealing the full clinical spectrum of PCD.4

PICADAR: 7 Parameters for Diagnosing PCD

“PCD has historically been underdiagnosed in the pediatric setting, resulting in a significant number of adult patients being present in the community with regular symptoms of PCD but undiagnosed,” noted Behran et al in a 2016 article published in European Respiratory Journal.5 “It is likely in other communities without an easily accessible diagnostic service and general awareness of PCD in the medical community that similar late diagnoses are occurring, and  that some adult patients remain undiagnosed.”2

In addition to the 4 major criteria for diagnosing PCD in young patients, the 7 parameters of the Primary Ciliary Dyskinesia Rule (PICADAR) could aid in the diagnosis when evaluating patients who have a persistent wet cough.2,5 The criteria are arranged in order of their odds ratio (OR) for PCD5:

  • Situs inversus (OR, 34.48; 95% CI, 11.6-101.8)
  • Full-term gestation (OR, 9.06; 95% CI, 2.9-27.4)
  • Neonatal chest symptoms (OR, 6.79; 95% CI, 2.7-16.7)
  • Neonatal intensive care admittance (OR, 6.70; 95% CI, 2.7-16.3)
  • Congenital heart defect (OR, 4.83; 95% CI, 1.1-22.2)
  • Chronic rhinitis (OR, 3.40; 95% CI, 1.2-8.9)
  • Ear and hearing symptoms (OR, 2.59; 95% CI, 1.2-5.8)

Although 3 of the neonatal parameters may be difficult to ascertain in adult patients, the PICADAR criteria may provide clinicians with more diagnostic considerations. The sensitivity and specificity of the diagnostic tool were 90% and 75%, respectively, for patients scoring ≥5 of a possible 14 points.5

Summary and Clinical Applicability

Primary ciliary dyskinesia, a genetically heterogeneous disease, affects the motile cilia in the airways, ears, and Fallopian tubes. PCD is not always diagnosed in early childhood, as once previously thought.

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Limitations and Disclosures

None.

References

  1. O’Connor MG, Griffiths A, Iyer NP, Shapiro AJ, Wilson KC, Thomson CC. Clinical practice guideline: summary for clinicians. Diagnosis of primary ciliary dyskinesia [published online November 15, 2018]. Ann Am Thorac Soc. doi:10.1513/AnnalsATS.201810-693CME
  2. Robinson P. Never too old for an inherited condition. Intern Med J. 2018;48(10):1252-1254.
  3. Horani A, Ferkol TW. Advances in the genetics of primary ciliary dyskinesia: clinical implications. CHEST. 2018;154(3):645-652.
  4. Shapiro AJ, Davis SD, Polineni D, et al. Diagnosis of primary ciliary dyskinesia. An official American Thoracic Society Clinical Practice Guideline. Am J Respir Crit Care Med. 2018;197(12):e24-e39.
  5. Behan L, Dimitrov BD, Kuehni CE, et al. PICADAR: a diagnostic predictive tool for primary ciliary dyskinesia. Eur Respir J. 2016;47(4):1103-1112.