Genotype–Computed Tomography Phenotype of the RSPH4A Founder Variant in Primary Ciliary Dyskinesia

Background/Objectives: Primary ciliary dyskinesia (PCD) caused by biallelic RSPH4A variants is enriched in the Puerto Rican population due to the founder allele c.921+3_921+6delAAGT, a 4-nucleotide deletion affecting the intron 6 splice donor. This study aimed to characterize the genotype–computed tomography (CT) phenotype associated with homozygosity for this founder variant and examine relationships among age, pulmonary function, and structural lung disease.

Methods

We performed a cross-sectional analysis of 20 genetically confirmed patients homozygous for RSPH4A c.921+3_921+6delAAGT. Demographic characteristics, spirometry, and chest CT findings were evaluated. Structural disease burden was quantified using a Bhalla-style CT severity score, and regression analyses assessed associations among age, CT severity, sex, and forced expiratory volume in 1 s (FEV1).