Gene expression during ciliagenesis: Towards a novel candidate gene list for Primary Ciliary Dyskinesia

Primary Ciliary Dyskinesia (PCD) is a hereditary disorder occurring in
1:15.000-30.000 live births, with increased frequency in genetically isolated
populations. PCD is characterised by dyskinesia of epithelial cilia causing
chronic respiratory disease. Diagnosing patients can be challenging, as there
is no gold standard test. Due to the many unknown disease causing gene defects,
genetic testing is still not possible in most cases. To this date, our
understanding of the molecular composition of cilia is far from complete.
Investigating which genes are important in cilia genesis will contribute to a
more complete candidate gene list and development of a diagnostic test for
Primary Ciliary Dyskinesia.

We aim to assess gene expression patterns in cilia-producing cells from healthy
controls to develop a candidate gene list for PCD.

This observational study will be conducted at the VU University Medical Center.
Nasal curette and brush biopsies will be performed on healthy volunteers to
obtain respiratory epithelial cells. Cells will be cultured and RNA will be
isolated at three different time points during cilia genesis. Subsequently, RNA
will be enriched for mRNA, fragmented and copied into cDNA. Next generation
sequencing of these fragments will show the number of fragments per transcript
to obtain an estimate for gene expression levels. Differential gene expression
for different time points will be tested and we will asess whether all known
PCD genes show a similar gene expression pattern.

Healthy volunteers participating in this study will undergo a nasal curette and
brush biopsy to obtain normal functioning respiratory epithelial cells. There
are no risks associated with this procedure. The procedure may cause temporary
discomfort during the scraping or brushing of the nasal mucous membrane. This
resides immediately after the curette or brush is removed. In rare cases,
slight and temporary bleeding of the nasal mucosa may occur. This usually only
happens when the mucosa is irritated or infected. To minimize this risk,
subjects with any respiratory symptoms will be excluded from the study. PCD
patients will benefit from the results of this study as a more complete gene
candidate list can be developed which will enable genetic testing in the
future. In addition, comparing the cell culture success rate of the less
invasive brush biopsy, with the rate of the curette biopsy, will indicate its
clinical utility.