Introduction: Individuals with primary ciliary dyskinesia (PCD) frequently complain of olfactory dysfunction, but this deficit is poorly documented in the literature. The purpose of this study was to 1) characterize the presence and degree of olfactory dysfunction in PCD compared to controls and 2) whether certain PCD genes are associated with worse olfaction.
Methods: We prospectively administered the University of Pennsylvania Smell Identification Test (UPSIT) to individuals with PCD (ages >15 years) at a tertiary referral center. Participants were divided into 3 age groups (15-29 years, 30-44 years, 45+ years) and were compared to N=2170 age and sex-matched participants with normative olfaction data.
Results: 29 (8 males, 21 females) individuals with PCD met criteria (median age: 38 years; interquartile range:22-47). Only 27.6% of patients with PCD had UPSIT scores within the normosmia range. The UPSIT median scores of each PCD age group was significantly lower than median scores of the controls (p < 0.0001 for each age group). UPSIT scores generally worsened with age: mean 33 (mild hyposmia) for 15-29 years, 26.8 for 30-44 years (moderate hyposmia), and 20.9 (severe hyposmia) for 45+ years. The most common genes coded for inner dynein arms/microtubule dysfunction (11/29, 37.9%) followed by outer dynein arm dysfunction (8/29, 27.6%). No specific gene was associated with worse olfactory dysfunction.
Conclusion: Individuals with PCD have a substantially higher prevalence and degree of olfactory dysfunction compared to age-matched controls. Our study is the first to suggest greater olfactory dysfunction with age in PCD, highlighting an important area for further study. No single gene was associated with worse olfaction.