Olfactory Dysfunction in Primary Ciliary Dyskinesia

Objective: Individuals with primary ciliary dyskinesia (PCD) frequently report olfactory dysfunction, yet this deficit is poorly documented. The purpose of this study was to characterize the presence and degree of olfactory dysfunction in PCD compared to controls and determine whether certain PCD genes are associated with worse olfaction. Study Design: A prospective cohort study. Setting: Tertiary referral center. Methods: We administered the University of Pennsylvania Smell Identification Test (UPSIT) to individuals with PCD. Participants were divided into 3 age groups (15-29 years, 30-44 years, and 45+ years) and compared to age- and sex-matched normal controls (n = 2170). Results: Twenty-nine individuals with PCD (8 males and 21 females) met the 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 were significantly lower than the median scores of the controls (P <.0001 for each age group). UPSIT scores generally worsened with age: mean 33 (mild hyposmia) for 15 to 29 years, 26.8 (moderate hyposmia) for 30 to 44 years, and 20.9 (severe hyposmia) for 45+ years. The most common genes coded were absent inner dynein arm/microtubule disorientation (IDA/MTD) defect (11/24, 45.8%), followed by absent outer dynein arm defect (8/24, 33.3%). The CCDC39 gene (IDA/MTD) 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 report greater olfactory dysfunction with age in PCD patients, highlighting an important area for research.