Phenotypic Mutation 'Defenseless' (pdf version)
Mutation Type missense
Coordinate25,028,927 bp (GRCm39)
Base Change A ⇒ G (forward strand)
Gene Dock8
Gene Name dedicator of cytokinesis 8
Synonym(s) 1200017A24Rik, 5830472H07Rik, A130095G14Rik
Chromosomal Location 24,976,898-25,179,796 bp (+) (GRCm39)
MGI Phenotype FUNCTION: [Summary is not available for the mouse gene. This summary is for the human ortholog.] This gene encodes a member of the DOCK180 family of guanine nucleotide exchange factors. Guanine nucleotide exchange factors interact with Rho GTPases and are components of intracellular signaling networks. Mutations in this gene result in the autosomal recessive form of the hyper-IgE syndrome. Alternatively spliced transcript variants encoding different isoforms have been described.[provided by RefSeq, Jun 2010]
PHENOTYPE: Mice homozygous for inactivating mutations of this gene exhibit loss of marginal zone B cells, decrease in peritoneal B1 cells and peripheral naive T cells, failure of sustained antibody response after immunization, failure of germinal center persistence, and failure of B cell affinity maturation. [provided by MGI curators]
Accession Number

NCBI RefSeq: NM_028785; MGI:1921396

Amino Acid Change Threonine changed to Alanine
Institutional SourceBeutler Lab
Gene Model predicted gene model for protein(s): [ENSMUSP00000025831]
AlphaFold Q8C147
PDB Structure Crystal structure of the DHR-2 domain of DOCK8 in complex with Cdc42 (T17N mutant) [X-RAY DIFFRACTION]
SMART Domains Protein: ENSMUSP00000025831
Gene: ENSMUSG00000052085
AA Change: T44A

Pfam:DUF3398 71 164 3.9e-25 PFAM
Pfam:DOCK-C2 557 739 6.7e-49 PFAM
low complexity region 786 803 N/A INTRINSIC
low complexity region 1003 1020 N/A INTRINSIC
low complexity region 1123 1138 N/A INTRINSIC
low complexity region 1236 1246 N/A INTRINSIC
low complexity region 1371 1383 N/A INTRINSIC
Pfam:DHR-2 1534 2060 5e-210 PFAM
Predicted Effect probably benign

PolyPhen 2 Score 0.002 (Sensitivity: 0.99; Specificity: 0.30)
(Using ENSMUST00000025831)
Meta Mutation Damage Score 0.0593 question?
Is this an essential gene? Probably nonessential (E-score: 0.083) question?
Phenotypic Category Unknown
Candidate Explorer Status loading ...
Single pedigree
Linkage Analysis Data
Alleles Listed at MGI

All Mutations and Alleles(17) : Chemically induced (ENU)(5) Endonuclease-mediated(2) Gene trapped(4) Spontaneous(2) Targeted(4)

Lab Alleles
AlleleSourceChrCoordTypePredicted EffectPPH Score
captain_morgan APN 19 25105076 critical splice donor site probably benign
primurus APN 19 25160973 missense probably damaging 1.00
IGL00737:Dock8 APN 19 25160340 missense probably benign 0.00
IGL00755:Dock8 APN 19 25028873 missense probably benign 0.09
IGL00822:Dock8 APN 19 25165773 nonsense probably null
IGL00838:Dock8 APN 19 25152823 nonsense probably null
IGL01419:Dock8 APN 19 25096816 missense probably benign 0.08
IGL01456:Dock8 APN 19 25096863 missense possibly damaging 0.95
IGL01532:Dock8 APN 19 25146805 missense probably damaging 0.99
IGL01602:Dock8 APN 19 25067252 splice site probably benign
IGL01605:Dock8 APN 19 25067252 splice site probably benign
IGL01753:Dock8 APN 19 25038656 splice site probably benign
IGL01843:Dock8 APN 19 25067292 missense probably benign 0.02
IGL02032:Dock8 APN 19 25107769 missense probably damaging 0.99
IGL02073:Dock8 APN 19 25178350 critical splice acceptor site probably null
IGL02192:Dock8 APN 19 25055569 critical splice donor site probably null
IGL02402:Dock8 APN 19 25055509 missense probably benign 0.25
IGL02529:Dock8 APN 19 25078290 nonsense probably null
IGL02728:Dock8 APN 19 25109584 missense probably benign
IGL02739:Dock8 APN 19 25165852 missense probably damaging 1.00
IGL03037:Dock8 APN 19 25063545 missense probably benign 0.02
IGL03104:Dock8 APN 19 25178384 nonsense probably null
IGL03137:Dock8 APN 19 25133312 missense probably benign 0.19
IGL03365:Dock8 APN 19 25077048 missense possibly damaging 0.70
Guardate UTSW 19 25127195 missense probably benign
hillock UTSW 19 25151697 critical splice donor site probably null
Molehill UTSW 19 25107825 missense probably damaging 1.00
Pap UTSW 19 25099805 missense probably benign 0.31
Papilla UTSW 19 25055448 nonsense probably null
snowdrop UTSW 19 25162305 critical splice donor site probably null
warts_and_all UTSW 19 25146865 critical splice donor site probably null
R0021:Dock8 UTSW 19 25140411 missense probably benign 0.01
R0147:Dock8 UTSW 19 25096823 missense probably benign 0.00
R0148:Dock8 UTSW 19 25096823 missense probably benign 0.00
R0294:Dock8 UTSW 19 25165714 missense probably damaging 1.00
R0537:Dock8 UTSW 19 25148941 missense probably benign 0.08
R0630:Dock8 UTSW 19 25038524 missense probably benign 0.10
R1163:Dock8 UTSW 19 25028867 missense probably benign
R1164:Dock8 UTSW 19 25067391 missense probably benign 0.44
R1471:Dock8 UTSW 19 25178400 missense possibly damaging 0.74
R1477:Dock8 UTSW 19 25072914 missense possibly damaging 0.95
R1633:Dock8 UTSW 19 25028927 missense probably benign 0.00
R1803:Dock8 UTSW 19 25109599 missense probably benign 0.00
R1822:Dock8 UTSW 19 25138422 missense probably benign 0.31
R1852:Dock8 UTSW 19 25104492 missense probably benign 0.45
R1916:Dock8 UTSW 19 25038521 missense probably benign 0.02
R1984:Dock8 UTSW 19 25098545 missense probably null
R2311:Dock8 UTSW 19 25160368 missense possibly damaging 0.93
R2341:Dock8 UTSW 19 25177757 missense probably damaging 0.99
R2483:Dock8 UTSW 19 25057241 missense probably benign
R3116:Dock8 UTSW 19 25165858 missense probably benign 0.00
R3157:Dock8 UTSW 19 25127195 missense probably benign
R3623:Dock8 UTSW 19 25057241 missense probably benign
R3624:Dock8 UTSW 19 25057241 missense probably benign
R3800:Dock8 UTSW 19 25141716 missense probably benign 0.08
R3844:Dock8 UTSW 19 25042794 nonsense probably null
R3895:Dock8 UTSW 19 25028865 missense probably benign 0.31
R3901:Dock8 UTSW 19 25078269 missense possibly damaging 0.69
R3959:Dock8 UTSW 19 25162305 critical splice donor site probably null
R4428:Dock8 UTSW 19 25042754 missense probably benign 0.00
R4428:Dock8 UTSW 19 25177863 missense probably damaging 0.98
R4429:Dock8 UTSW 19 25042754 missense probably benign 0.00
R4431:Dock8 UTSW 19 25042754 missense probably benign 0.00
R4545:Dock8 UTSW 19 25165722 missense probably damaging 1.00
R4839:Dock8 UTSW 19 25146858 missense probably benign 0.00
R4897:Dock8 UTSW 19 25159001 missense probably benign 0.00
R4939:Dock8 UTSW 19 25099764 missense probably damaging 1.00
R4995:Dock8 UTSW 19 25135747 missense probably benign 0.02
R5035:Dock8 UTSW 19 25063571 missense probably damaging 0.99
R5294:Dock8 UTSW 19 25038517 missense probably benign 0.01
R5324:Dock8 UTSW 19 25140458 missense probably benign 0.17
R5478:Dock8 UTSW 19 25057186 missense probably benign
R5704:Dock8 UTSW 19 25151586 missense probably damaging 1.00
R5724:Dock8 UTSW 19 25099785 missense probably damaging 1.00
R5745:Dock8 UTSW 19 25107761 missense probably benign 0.02
R5864:Dock8 UTSW 19 25038584 missense probably damaging 0.99
R5870:Dock8 UTSW 19 25109490 missense probably benign
R5893:Dock8 UTSW 19 25099811 missense probably damaging 1.00
R5954:Dock8 UTSW 19 25148983 missense probably damaging 1.00
R6087:Dock8 UTSW 19 25138438 missense probably benign 0.00
R6223:Dock8 UTSW 19 25138416 missense probably benign 0.00
R6391:Dock8 UTSW 19 25072914 missense possibly damaging 0.95
R6759:Dock8 UTSW 19 25104848 missense probably damaging 0.99
R6786:Dock8 UTSW 19 25160386 missense possibly damaging 0.49
R6794:Dock8 UTSW 19 25099805 missense probably benign 0.31
R6818:Dock8 UTSW 19 25146865 critical splice donor site probably null
R6885:Dock8 UTSW 19 25124742 missense possibly damaging 0.95
R6908:Dock8 UTSW 19 25165746 missense probably damaging 1.00
R6923:Dock8 UTSW 19 25072970 missense probably benign
R7001:Dock8 UTSW 19 25077041 missense probably benign
R7141:Dock8 UTSW 19 25158984 missense probably null 0.75
R7203:Dock8 UTSW 19 25158927 missense probably damaging 1.00
R7257:Dock8 UTSW 19 25104449 missense probably benign 0.08
R7296:Dock8 UTSW 19 25162245 missense probably benign 0.00
R7538:Dock8 UTSW 19 25135782 missense probably damaging 1.00
R7555:Dock8 UTSW 19 25152764 missense probably damaging 0.99
R7641:Dock8 UTSW 19 25151697 critical splice donor site probably null
R7764:Dock8 UTSW 19 25074899 missense probably benign
R7859:Dock8 UTSW 19 25160934 missense probably damaging 1.00
R7864:Dock8 UTSW 19 25140864 missense possibly damaging 0.95
R8090:Dock8 UTSW 19 25131606 missense probably damaging 1.00
R8160:Dock8 UTSW 19 25124711 missense probably damaging 1.00
R8287:Dock8 UTSW 19 25107825 missense probably damaging 1.00
R8295:Dock8 UTSW 19 25100600 missense probably benign 0.04
R8443:Dock8 UTSW 19 25133281 missense probably benign 0.04
R8537:Dock8 UTSW 19 25107870 missense probably benign 0.00
R8673:Dock8 UTSW 19 25160867 missense probably damaging 0.96
R8709:Dock8 UTSW 19 25055448 nonsense probably null
R8834:Dock8 UTSW 19 25140834 missense probably benign 0.16
R8991:Dock8 UTSW 19 25165731 missense possibly damaging 0.82
R9292:Dock8 UTSW 19 25160995 splice site probably benign
R9509:Dock8 UTSW 19 25072985 missense probably benign 0.00
R9526:Dock8 UTSW 19 25165739 missense probably benign 0.10
R9622:Dock8 UTSW 19 25098545 missense probably null
R9634:Dock8 UTSW 19 25169585 missense probably damaging 1.00
R9654:Dock8 UTSW 19 25124710 missense probably damaging 1.00
R9670:Dock8 UTSW 19 25148926 missense probably null 0.01
R9699:Dock8 UTSW 19 25133388 critical splice donor site probably null
R9726:Dock8 UTSW 19 25154374 missense probably damaging 0.97
R9765:Dock8 UTSW 19 25146832 missense possibly damaging 0.94
X0027:Dock8 UTSW 19 25138493 missense probably benign
Z1177:Dock8 UTSW 19 25133336 missense probably benign 0.16
Z1177:Dock8 UTSW 19 25109487 missense probably benign 0.05
Mode of Inheritance Unknown
Local Stock
Last Updated 2019-09-04 9:31 PM by Diantha La Vine
Record Created 2019-01-22 11:02 AM by Bruce Beutler
Record Posted 2019-02-01
Phenotypic Description

Figure 1. Defenseless mice exhibit decreased frequencies of peripheral CD8+ T cells. Flow cytometric analysis of peripheral blood was utilized to determine T cell frequency. Normalized data are shown. Abbreviations: WT, wild-type; REF, homozygous reference mice; HET, heterozygous variant mice; VAR, homozygous variant mice. Mean (μ) and standard deviation (σ) are indicated.

The Defenseless phenotype was identified among G3 mice of the pedigree R1633, some of which showed reduced frequencies of CD8+ T cells in the peripheral blood (Figure 1).

Nature of Mutation

Figure 2. Linkage mapping of the reduced CD8+ T cell frequency using a dominant model of inheritance. Manhattan plot shows -log10 P values (Y-axis) plotted against the chromosome positions of 63 mutations (X-axis) identified in the G1 male of pedigree R1633. Normalized phenotype data are shown for single locus linkage analysis without consideration of G2 dam identity. Horizontal pink and red lines represent thresholds of P = 0.05, and the threshold for P = 0.05 after applying Bonferroni correction, respectively.

Whole exome HiSeq sequencing of the G1 grandsire identified 63 mutations. The reduced CD8+ T cell frequency phenotype was linked by continuous variable mapping to a mutation in Dock8: an A to G transition at base pair 25,051,563 (v38) on chromosome 19, or base pair 52,053 in the GenBank genomic region NC_000085 encoding the Dock8 gene. Linkage was found with a dominant model of inheritance, wherein one variant homozygote and eight heterozygous mice departed phenotypically from nine homozygous reference mice with a P value of 0.000763 (Figure 2).

The mutation corresponds to residue 252 in the mRNA sequence NM_028785 within exon 2 of 48 total exons.


38  -R--H--S--I--S--T--S--G--F--P--S-

The mutated nucleotide is indicated in red. The mutation results in a threonine to alanine substitution at position 44 (T44A) in the DOCK8 protein, and is strongly predicted by Polyphen-2 to be benign (score = 0.002).

Illustration of Mutations in
Gene & Protein
Protein Prediction

Figure 3. Domain structure of DOCK8, a member of the DOCKC subfamily. The DHR-1 domain shares a weak homology to the C2 domain. The large DHR-2 domain interacts with the nucleotide-free form of Rac and/or Cdc42. The Defenseless mutation results in a threonine to alanine substitution at position 44 (T44A). This image is interactive. Other mutations found in DOCK8 are noted in red. Click on each mutation for more specific information.

DOCK8 belongs to the DOCK180 superfamily of guanine nucleotide exchange factors (GEFs) that have been shown to activate members of the Rho family of small GTPases (1-4). The DOCK C subfamily (which includes DOCK8 and DOCK7; see the record for moonlight) has dual specificity for Rac and Cdc42 (1;3;5;6).  Two domains are shared amongst all DOCK proteins, the catalytic DHR-2 (DOCK homology region 2) or CZH-2 (CDM-zizimin homology 2) domain and the DHR-1 or CZH-1 domain (Figure 3).  The DHR-1 domain is located N-terminal to the DHR-2 domain (2;4).

The Defenseless mutation results in a threonine to alanine substitution at position 44 (T44A). Thr44 is within an undefined region preceding the DHR-1 domain.

Please see the record for captain morgan for more information on Dock8.

Putative Mechanism

The Rho GTPases are known regulators of the actin cytoskeleton and affect multiple cellular activities including cell morphology, polarity, migration, proliferation and apoptosis, phagocytosis, cytokinesis, adhesion, vesicular transport, transcription and neurite extension and retraction. Like DOCK2, DOCK8 is likely to regulate the activity of GTPases and thus be involved in cytoskeletal changes associated with various cellular processes. DOCK8 is proposed to serve as an effector downstream of CD19 and PI3K to promote G protein signaling events critical for integrin polarization at the synapse and for the survival of marginal zone B cells and germinal center (GC) B cells. 

During a T cell-dependent humoral immune response, CD4+ T helper cell subsets including TFH, Th1 and Th2 cells migrate to the T cell/B cell borders in SLO, and interact with cognate antigen-specific B cells through the pairing of T cell and B cell surface ligands and receptors such as CD40 with its ligand (see the record for walla).  This interaction results in the secretion by T helper cells of certain cytokines known to promote B cell survival, proliferation, and antibody production (7;8).

In humans, DOCK8 deficiency results in an autosomal recessive form of hyper-IgE recurrent infection syndrome (HIES; OMIM #243700) (9;10).  Autosomal dominant HIES is characterized by recurrent Staphylococcus aureus skin abscesses, increased serum IgE, and abnormalities of the connective tissue, skeleton, and dentition (11).  The autosomal recessive form shares hyper-IgE, eosinophilia, and recurrent Staphylococcal infections, but is distinguished from autosomal dominant HIES by the lack of connective tissue and skeletal involvement (12). Patients with DOCK8 deficiency are unusually susceptible to viral infections and virally-caused cancers.  Reduced numbers of T, B, and NK cells have been reported along with a selective defect in CD8+ T cell activation (9).  However, another study suggests most patients have normal numbers of B and NK cells, a greater decrease in the CD4+ T cell population than the CD8+ T cell population, and a more comprehensive T cell activation defect involving both T cell subsets (10).  Both autosomal dominant and autosomal recessive HIES are linked to a lack of Th17 cell function including the failure to produce the interleukin 17 (IL-17) cytokine (12).  Th17 are a subset of CD4+ T helper cells that play an important role in the development of autoimmune diseases like rheumatoid arthritis, as well as being critical in the clearance of fungal and extracellular bacterial infections (13).    

The relatively normal initiation of antibody production by mice with Dock8 mutations suggests that the extrafollicular B cell clonal expansion, plasma cell formation and immunoglobulin class switching, which depends on interactions with T helper cells, is intact.  However, subsequent antibody responses and affinity maturation occurring in the GCs is significantly impaired. The humoral deficits are due to a defect in GC B cell survival and selection during the affinity maturation phase of GC responses (14).

The phenotype of the Defenseless mice indicates loss of DOCK8-associated function.

Primers PCR Primer

Sequencing Primer

PCR program

1) 94°C 2:00
2) 94°C 0:30
3) 55°C 0:30
4) 72°C 1:00
5) repeat steps (2-4) 40x
6) 72°C 10:00
7) 4°C hold

The following sequence of 400 nucleotides is amplified (chromosome 19, + strand):

1   tggaagtgct ctgctcacaa ctcagccaag aactgcgttg ggattatagt gtgttgggtt
61  agtttaaatt aatcacttca tggagatttt ttttttctat tttaattcta ggtattcatc
121 gtcagaaata aggaagcagt ttacgctccc acccaacctc ggacagtacc atcggcacag
181 tatcagtaca tctggtttcc cctctcttca gctagtaagt atgcattaca ggtttggtgg
241 gtcagtggtc agggactgaa gtacccagca tctacacccc tcccccacac cagccttagc
301 tcctgttgca cctagcgttc tctgcccact gcttcgtaac tctgctagcc cttagacatc
361 agacatctcc ctctggcgtg tatagaatga gacagcccag 

Primer binding sites are underlined and the sequencing primers are highlighted; the mutated nucleotide is shown in red.

Science Writers Anne Murray
Illustrators Diantha La Vine
AuthorsXue Zhong, Jin Huk Choi, and Bruce Beutler