HGNC Approved Gene Symbol: C2CD3
SNOMEDCT: 763837007;
Cytogenetic location: 11q13.4 Genomic coordinates (GRCh38) : 11:74,012,718-74,171,002 (from NCBI)
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
|---|---|---|---|---|
| 11q13.4 | Orofaciodigital syndrome XIV | 615948 | Autosomal recessive | 3 |
Based on experiments in mice, C2CD3 is predicted to be an essential regulator of cilia formation, hedgehog signaling (see SHH, 600725), and embryonic patterning (Hoover et al., 2008). C2CD3 is also a positive regulator of centriole length (Thauvin-Robinet et al., 2014).
Hoover et al. (2008) cloned mouse C2cd3. The deduced 2,322-amino acid protein has a calculated molecular mass of approximately 250 kD. It has 5 C2 domains predicted to mediate interactions with proteins and membrane lipids. C2cd3 was expressed ubiquitously in mouse embryos between embryonic day 8.5 (E8.5) and E10.5. Fluorescence-tagged C2cd3 localized to the ciliary basal body in transfected mouse embryonic fibroblasts (MEFs). Orthologs of C2cd3 were detected in vertebrates, including human, but not in invertebrates.
Thauvin-Robinet et al. (2014) reported that C2CD3 contains a C2-like N-terminal domain, followed by 6 canonical C2 domains predicted to bind calcium and phospholipid headgroups. Fluorescence-tagged mouse C2cd3 localized to centriolar satellites and to the distal lumen of mature centrioles and procentrioles, near the distal tip. Database analysis revealed orthologs of C2CD3 in organisms that assemble centrioles or cilia.
By genomic sequence analysis, Hoover et al. (2008) mapped the C2CD3 gene to human chromosome 11q13.4 and mouse chromosome 7.
Using coimmunoprecipitation analysis, Thauvin-Robinet et al. (2014) found that endogenous C2CD3 interacted with OFD1 (300170) in human RPE cells. Epitope-tagged human OFD1 also interacted with fluorescence-tagged mouse C2cd3 in vitro. RPE cells overexpressing fluorescence-tagged mouse C2cd3 developed hyperelongated centrioles and centriole-like microtubular rods in various regions of the cytoplasm. Coexpression of mouse Ofd1 with C2cd3 reduced the frequency of hyperelongated centrioles in transfected U2OS cells.
Using wildtype and C2cd3-null MEFs, Ye et al. (2014) determined that localization of C2cd3 to centriolar satellites depended on Pcm1 (600299) and dynein (see 600112)-mediated retrograde transport. Localization of C2cd3 to distal ends of the mother and daughter centrioles was required for recruitment of the distal appendage proteins Ccdc41 (CEP83; 615847), Sclt1 (611399), Cep89 (615470), Fbf1 (616807), and Cep164 (614848) and for the intraflagellar transport B proteins Ift88 (600595) and Ift52 (617094). In the absence of C2cd3, Ttbk2 (611695) was not recruited to the distal end of the mother centriole, and Cp110 (609544) was not removed. C2cd3 was also required for docking of ciliary vesicles to the mother centriole. Ye et al. (2014) concluded that C2CD3 regulates initiation of ciliogenesis through centriolar maturation, ciliogenic protein recruitment, and ciliary vesicle docking.
In a 4-year-old boy with orofaciodigital syndrome (OFD14; 615948), Thauvin-Robinet et al. (2014) identified a homozygous truncating mutation in the C2CD3 gene (R62X; 615944.0001). The mutation was found by whole-exome sequencing and segregated with the disorder in the family. Sequencing of the coding exons of C2CD3 in 34 patients with OFD identified 1 fetus who was compound heterozygous for 2 mutations in the C2CD3 gene (615944.0002 and 615944.0003). Functional studies of the 3 variants were not performed, but Thauvin-Robinet et al. (2014) demonstrated that C2CD3 is required for cilium assembly and function, consistent with OFD being a ciliopathy. Moreover, hypomorphic or null mutations in this gene in mice cause a phenotype consistent with a ciliopathy (see ANIMAL MODEL).
From a cohort of 43 French Canadian patients from 35 families diagnosed with Joubert syndrome (see 213300), Srour et al. (2015) identified 2 sibs (family 472) who were compound heterozygous for a missense (G1743C) and a nonsense (R1977X) mutation in the C2CD3 gene. The patients exhibited MTS and severe global developmental delay with hypotonia and ataxia, but information regarding oral, facial, and digital features was not reported.
In 2 fetuses with a 'skeletal ciliopathy' from a Lebanese-Palestinian family, Cortes et al. (2016) identified compound heterozygous mutations in C2CD3, W65C a I477X. Analysis of patient fibroblasts under ciliogenic conditions showed a reduction in the percentage of cells with a cilium compared to controls. In addition, there was a defect in localization of IFT88 (600595) at the centrioles in the nonciliated cells, and CP110 (CCP110; 609544) was not efficiently removed from the mother centriole in patient cells. The authors noted that the defect in uncapping the mother centriole involves one of the earliest steps in ciliogenesis which, together with the inability to correctly localize IFT88, represents a block to the subsequent steps in ciliogenesis.
In 5 children from 3 unrelated 'ciliopathy pedigrees,' Boczek et al. (2018) performed whole-exome sequencing and identified compound heterozygous mutations in the C2CD3 gene in all (see, e.g., 615944.0004 and 615944.0005). The unaffected parents were each heterozygous for 1 of the mutations, which were either not present or present at extremely low frequency (less than 0.001%) in the gnomAD database. Noting the phenotypic diversity exhibited by their patients, the authors concluded that biallelic variants in C2CD3 can cause a spectrum of ciliopathy disorders.
In a genetic screen in mice, Hoover et al. (2008) identified 'hearty' (hty), a recessive mutation that disrupted embryonic development and caused lethality between E11 and E13. Some hty/hty mutants exhibited exencephaly in the midbrain and posterior forebrain, a twisted body axis, right heart looping, and pericardial edema. Hty/hty mutants that underwent neural tube closure presented with a tight mesencephalic flexure. At E12.5, all hty/hty mutants exhibited severe polydactyly in all 4 limbs. Nodal (601265) and Lefty2 (601877) were expressed in both left and right lateral plate mesoderm, suggesting loss of left-right asymmetry. Hoover et al. (2008) identified the hty mutation as a C-to-A transversion at the first nucleotide of intron 4 of the C2cd3 gene, resulting in disrupted splicing and truncation of the C2cd3 protein. Homozygous disruption of C2cd3 via gene trap (gt) insertion resulted in a similar phenotype, as did hty/gt transheterozygosity. Ventral node cells of hty/hty and gt/gt embryos and hty/hty MEFs showed disrupted cilia formation. Immunofluorescence analysis, Western blot analysis, and gene expression profiling revealed disrupted patterning, processing, and expression of proteins involved in hedgehog signaling in C2cd3 mutant embryos.
Using immunofluorescence analysis and electron microscopy, Thauvin-Robinet et al. (2014) showed that centriolar distal appendages and subdistal appendages were absent from hty/hty and C2cd3-null mouse embryonic fibroblasts. C2cd3 mutant centrioles, which were shorter than wildtype, also showed reduced Ofd1 content.
In a boy, born of consanguineous parents, with orofaciodigital syndrome XIV (OFD14; 615948), Thauvin-Robinet et al. (2014) identified a homozygous c.184C-T transition in exon 2 of the C2CD3 gene, resulting in an arg62-to-ter (R62X) substitution. The mutation was found by a combination of homozygosity mapping and exome sequencing and was confirmed by Sanger sequencing. The mutation segregated with the disorder in the family was not present in the Exome Variant Server database. Functional studies of this variant were not performed.
In a male fetus with orofaciodigital syndrome XIV (OFD14; 615948), Thauvin-Robinet et al. (2014) identified 2 compound heterozygous mutations in the C2CD3 gene: a c.3085T-G transversion in exon 17, resulting in a cys1029-to-gly (C1029G) substitution, and an A-to-T transversion in the splice acceptor site of intron 21 (c.3911-2A-T; 615944.0003), resulting in a splice site mutation, a 4-bp frameshift deletion (c.3911_3914delCAAG), and premature termination (Ala1304ValfsTer3). Each unaffected parent was heterozygous for 1 of the mutations. This patient was ascertained from a cohort of 34 individuals with OFD who were screened for mutations in the coding exons of C2CD3. Neither mutation was found in the Exome Variant Server database. Functional studies were not performed on these variants.
For discussion of the splice site mutation in the C2CD3 gene (c.3911-2A-T) that was found in compound heterozygous state in a fetus with orofaciodigital syndrome XIV (OFD14; 615948) by Thauvin-Robinet et al. (2014), see 615944.0002.
In 2 sibs (family 1) with orofaciodigital syndrome XIV (OFD14; 615948), Boczek et al. (2018) identified compound heterozygosity for splicing mutations in the C2CD3 gene: a c.1365+1G-A transition (c.1365+1G-A, NM_001286577.1) in intron 8, and a c.5090+5G-C transversion in intron 25, both predicted to result in premature termination codons (Ser406ArgfsTer23 and Ser1652TyrfsTer26, respectively). The unaffected parents were each heterozygous for 1 of the mutations; the first variant was present in the gnomAD database at a minor allele frequency of 0.000004, whereas the second was not found in the gnomAD database. Sashimi plot analysis of RNA sequencing data showed that the c.1365+1G-A variant caused skipping of exon 8 in 28% of reads, resulting in the truncated Ser406ArgfsTer23 protein, and the c.5090+5G-C variant caused skipping of exon 25 in 35% of reads, resulting in the truncated Ser1652TyrfsTer26 protein. Experiments with puromycin provided evidence that the out-of-frame transcripts undergo nonsense-mediated decay.
For discussion of the c.5090+5G-C transversion (c.5090+5G-C, NM_001286577.1) in intron 25 of the C2CD3 gene, predicted to result in a premature termination codon (Ser1652TyrfsTer26), that was found in compound heterozygous state in a patient with orofaciodigital syndrome XIV (OFD14; 615948) by Boczek et al. (2018), see 615944.0004.
Boczek, N. J., Hopp, K., Benoit, L., Kraft, D., Cousin, M. A., Blackburn, P. R., Madsen, C. D., Oliver, G. R., Nair, A. A., Na, J., Bianchi, D. W., Beek, G., Harris, P. C., Pichurin, P., Klee, E. W. Characterization of three ciliopathy pedigrees expands the phenotype associated with biallelic C2CD3 variants. Europ. J. Hum. Genet. 26: 1797-1809, 2018. [PubMed: 30097616] [Full Text: https://doi.org/10.1038/s41431-018-0222-3]
Cortes, C. R., McInerney-Leo, A. M., Vogel, I., Rondon Galeano, M. C., Leo, P. J., Harris, J. E., Anderson, L. K., Keith, P. A., Brown, M. A., Ramsing, M., Duncan, E. L., Zankl, A., Wicking, C. Mutations in human C2CD3 cause skeletal dysplasia and provide new insights into phenotypic and cellular consequences of altered C2CD3 function. Sci. Rep. 6: 24083, 2016. Note: Electronic Article. [PubMed: 27094867] [Full Text: https://doi.org/10.1038/srep24083]
Hoover, A. N., Wynkoop, A., Zeng, H., Jia, J., Niswander, L. A., Liu, A. C2cd3 is required for cilia formation and Hedgehog signaling in mouse. Development 135: 4049-4058, 2008. [PubMed: 19004860] [Full Text: https://doi.org/10.1242/dev.029835]
Srour, M., Hamdan, F. F., McKnight, D., Davis, E., Mandel, H., Schwartzentruber, J., Martin, B., Patry, L., Nassif, C., Dionne-Laporte, A., Ospina, L. H., Lemyre, E., and 22 others. Joubert syndrome in French Canadians and identification of mutations in CEP104. Am. J. Hum. Genet. 97: 744-753, 2015. [PubMed: 26477546] [Full Text: https://doi.org/10.1016/j.ajhg.2015.09.009]
Thauvin-Robinet, C., Lee, J. S., Lopez, E., Herranz-Perez, V., Shida, T., Franco, B., Jego, L., Ye, F., Pasquier, L., Loget, P., Gigot, N., Aral, B., and 17 others. The oral-facial-digital syndrome gene C2CD3 encodes a positive regulator of centriole elongation. Nature Genet. 46: 905-911, 2014. [PubMed: 24997988] [Full Text: https://doi.org/10.1038/ng.3031]
Ye, X., Zeng, H., Ning, G., Reiter, J. F., Liu, A. C2cd3 is critical for centriolar distal appendage assembly and ciliary vesicle docking in mammals. Proc. Nat. Acad. Sci. 111: 2164-2169, 2014. [PubMed: 24469809] [Full Text: https://doi.org/10.1073/pnas.1318737111]