Table 1. PCD disease genes with associated ciliary defects and patient ethnicities.

Gene	Situs inversus	Ultrastructural defect	Video microscopy	Patient origin
ARMC4	Yes	ODA defects	Reduced numbers of ODAs and severely impaired ciliary beating	Consanguineous German of Turkish origin18
C21orf59	In some cases	Absent IDA and ODA or partial IDA and ODA defects	Complete paralysis	Ashkenazi Jewish, Brazilian, European American19
CCDC103	Yes	Variable defects in the IDA and ODA	Complete paralysis, reduced beat amplitude or loss of beat coordination	Consanguineous and of Pakistani or German origin20
CCDC114	In some cases	Loss of ODA	Abnormal ciliary motility to complete ciliary immotility with stiff or dyskinetic cilia	Isolated region of North Holland,21 UK,21 Caucasian22
CCDC39	In some cases	Absent/defective IDA, abnormal nexin links and radial spokes, axonemal disorganisation, normal ODA	Dyskinetic or akinetic ciliary motility, ciliary beating has reduced amplitude with rigid axonemes and fast, flickery movements	Algeria, Northern Africa, Tunisia, Germany, Turkey, France, Denmark, West Indies/Senegal, Egypt, Israel (some consanguineous)23
CCDC40	In some cases	Disorganization of the peripheral microtubular doublets, absent or shifted central pairs, partial or complete loss of IDA, abnormal radial spokes and nexin links, normal ODA	Markedly reduced beating amplitudes and rigid cilia with fast, flickery movements	Germany,24 Pakistan,24 Austria,24 Denmark,24 Yugoslavia,24 Hungary,24 Northern European6
CCDC65	No	Normal ODA, radial spokes, and central pairs but a reduction in IDA and nexin links	Stiff and dyskinetic cilia waveform	Ashkenazi Jewish19
DNAAF1	In some cases	Absent IDA and ODA	Unknown	Consanguineous German,25 Ethnicity not reported26
DNAAF2	In some cases	Combined IDA and ODA defects	Immotile cilia	Consanguineous but ethnicity not reported27
DNAAF3	In some cases	Combined IDA and ODA defects	Immotile cilia	Consanguineous Israeli, Saudi Arabian and Pakastani28
DYX1C1 (DNAAF4)	In some cases	Severe defects in IDA and ODA	Immotile cilia or cilia with a reduced beat frequency and amplitude	German,12 Belgian,12 Austrian,12 American,12 Consanguineous Irish,12 Irish Travellera
DNAH11	In some cases	Normal ciliary ultrastructure	Immotile or hyperkinetic cilia	German,29 Hispanic origin,30 Caucasian31
DNAH5	In some cases	Absent ODA; defects in IDA and ODA	Immotile cilia	Consanguineous and of Arabic origin,32 Lebanon,33 Germany,33 USA,33 England,33 Scotland,33 European,34 Asian-Indian,22 White22
DNAI1	In some cases	Absent ODA; absent IDA and ODA	Immotile cilia	Ethnicity not reported35, 36
DNAI2	In some cases	Defects in ODA	Not reported	Consanguineous Iranian Jewish kindred,37 Hungarian,37 German,37 Ashkenazi Jewish descent22
DNAL1	Yes	Absent or markedly shortened ODA	Absent or weakened ciliary movement	Consanguineous Bedouin families38
DRC1 (CCDC164)	No	Normal IDA and ODA but nexin links are lacking	Increased beat frequency with decreased bending amplitude	Austrian of Turkish ancestry, Swedish39
HEATR2	In some cases	Absent ODA and most outer doublets lack IDA	Virtually immotile cilia	Amish community40
HYDIN	No	Projection C2b absent at the central pair apparatus, most cilia have normal 9+2 axonemal composition, both IDA and ODA are normal	Reduced coordination of beating activity, reduced beating amplitudes and reduced bending capacity; some immotile cilia also	Consanguineous German,41 Faroe Islands,41 consanguineous family of European descent42
LRRC6	In some cases	Absent IDA and ODA	Immotile cilia	European descent (some consanguineous),43 Asian Pakastani families (some consanguineous),44 Turkish44
NME8 (TXNDC3)	Not known	Mixture of normal cilia and cilia with absent/shortened ODA	Persistent beating of cilia	Ethnicity not reported45
OFD1b	In some cases	Axonemal structure seems normal46	Airway epithelia ciliated cells: cilia are rare, disorganised and disorientated at the cell surface. The number of ciliated cells is restricted in lung epithelia.46	Multiple ethnicities
RPGRc,d	Not known	Partial dynein arm defects47	Not reported	Dutchc,48 White European ancestryc,49 Ethnicity not reportedd47
RSPH1	No	Ciliary central microtubule complex and radial-spoke defects	Coexistence of different ciliary beating patterns; cilia with a normal beat frequency but abnormal motion as well as immotile cilia or cilia with a slowed beat frequency	Consanguineous of North African descent,50 European descent50
RSPH4A	No	Transposition defect with complete absence of the central microtubule pair	Abnormal circular movement of cilia with a close to normal beat velocity	Pakastani,10 Northern European descent,10 Ethnicity not reported,50 Irish Travellera
RSPH9	No	Intermittent loss of the central pair observed by longitudinal-section electron microscopy	Abnormal circular movement of cilia with a close to normal beat velocity	Consanguineous Bedouin and Bedouin Bani Tameem tribe10
SPAG1	In some cases	Combined IDA and ODA defects	Nearly complete ciliary immotility and stiffness	Caucasian, South Asian descent, Ammish-Mennonite51
ZMYND10	In some cases	Absent/defective IDA and ODA; milder mutations associated with reduced but not absent IDA and ODA	Immotile cilia; milder mutations result in cilia with a slowed and stiff beating pattern	Israeli,44 Consanguineous Turkish,44 French,44 Hispanic origin,44 Northern European descent52

Abbreviations: IDA, inner dynein arm; ODA, outer dynein arm; PCD, primary ciliary dyskinesia.

^aCurrent study.

^bCauses X-linked oral facial digital syndrome type 1 and several other disorders with features that overlap OFD syndrome.

^cFamilies have X-linked retinitis pigmentosa with recurrent respiratory/sino-respiratory infections.

^dBrothers have primary ciliary dyskinesia and X-linked retinitis pigmentosa secondarily.