International consensus guideline for reporting transmission electron microscopy results in the diagnosis of primary ciliary dyskinesia (BEAT PCD TEM Criteria)

Abstract

Primary ciliary dyskinesia (PCD) is a heterogeneous genetic condition. European and North American diagnostic guidelines recommend transmission electron microscopy (TEM) as one of a combination of tests to confirm a diagnosis. However, there is no definition of what constitutes a defect or consensus on reporting terminology. The aim of this project was to provide an internationally agreed ultrastructural classification for PCD diagnosis by TEM.A consensus guideline was developed by PCD electron microscopy experts representing 18 centres in 14 countries. An initial meeting and discussion were followed by a Delphi consensus process. The agreed guideline was then tested, modified and retested through exchange of samples and electron micrographs between the 18 diagnostic centres.The final guideline a) provides agreed terminology and a definition of Class 1 defects which are diagnostic for PCD; b) identifies Class 2 defects which can indicate a diagnosis of PCD in combination with other supporting evidence; c) describes features which should be included in a ciliary ultrastructure report to assist multidisciplinary diagnosis of PCD; and d) defines adequacy of a diagnostic sample.This tested and externally validated statement provides a clear guideline for the diagnosis of PCD by TEM which can be used to standardise diagnosis internationally.

Frequency and Types of Ciliary Ultrastructural Defects in Patients With Suspected Primary Ciliary Dyskinesia Symptoms Analyzed by Transmission Electron Microscopy

“…Therefore, to con rm this diagnosis, they should present with other speci c PCD criteria. Repeating the biopsy and considering a su cient healthy interval before sampling also help to differentiate between PCD and SCD more precisely (14). IDA defect is also among the overlapping appearance seen in almost 30% of our samples, probably due to the di culty of seeing IDA by TEM (15)(16)(17).…”

Primary Ciliary Dyskinesia with Refractory Chronic Rhinosinusitis

“…Class 2 defects are a central complex defect, mislocalization of basal bodies with few or no cilia, microtubular disorganization defect with inner dynein arm present, outer dynein arm absence from 25% to 50% of cross sections, or combined inner and outer dynein arm absence from 25 to 50% of cross sections. In the present case, microtubular disorganization and inner dynein arm defect were observed in a hallmark transmission electron microscopic defects diagnosis [ 2 , 15 ].…”

A Revised Protocol for Culture of Airway Epithelial Cells as a Diagnostic Tool for Primary Ciliary Dyskinesia

“…Of 55 “PCD highly-unlikely” patients, a normal culture CBP was seen in 37 (67.3%) but remained equivocal in 16 (29.1%) and 2 were not cultured. Of seven “PCD”/“PCD highly-likely” patients, an abnormal “PCD likely” HSVA result was seen in five (71.4%), one was progressing but was deliberately “paused” and frozen due to “hallmark TEM defects” [ 14 ] and one patient failed due to infection ( Figure 2 ).…”

“…Ex vivo nasal or bronchial samples obtained by brushing or curette biopsy are imaged by high-speed video microscopy analysis (HSVA) [ 10 , 11 ] and ciliary motility analysed as a frontline functional test [ 12 ]. Transmission electron microscopy (TEM) is used to assess and quantify ultrastructural abnormalities of motile cilia [ 13 , 14 ]. Immunofluorescence labelling (IF) can demonstrate the absence or mis-localisation of ciliary proteins [ 15 , 16 ], particularly helpful in cases where no TEM abnormalities are detected such as with DNAH11 [ 17 ], DNAH9 [ 18 ] and HYDIN gene mutations [ 19 ].…”