Phenotypic Mutation 'Ekans' (pdf version)
AlleleEkans
Mutation Type splice site
Chromosome15
Coordinate78,343,627 bp (GRCm39)
Base Change T ⇒ A (forward strand)
Gene Tmprss6
Gene Name transmembrane serine protease 6
Synonym(s) matriptase-2, 1300008A22Rik
Chromosomal Location 78,323,867-78,352,834 bp (-) (GRCm39)
MGI Phenotype FUNCTION: [Summary is not available for the mouse gene. This summary is for the human ortholog.] The protein encoded by this gene is a type II transmembrane serine proteinase that is found attached to the cell surface. The encoded protein may be involved in matrix remodeling processes in the liver. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jan 2014]
PHENOTYPE: Homozygosity for an inactivating mutation of this gene results in hair loss over the entire body except the face, microcytic anemia and female infertility, all reversible by dietary iron supplementation. [provided by MGI curators]
Accession Number

NCBI RefSeq: NM_027902; MGI:1919003

MappedYes 
Amino Acid Change
Institutional SourceBeutler Lab
Gene Model predicted gene model for protein(s): [ENSMUSP00000017086 ] [ENSMUSP00000155414] [ENSMUSP00000155355 ] [ENSMUSP00000155549 ] [ENSMUSP00000155401 ]   † probably from a misspliced transcript
AlphaFold Q9DBI0
SMART Domains Protein: ENSMUSP00000017086
Gene: ENSMUSG00000016942

DomainStartEndE-ValueType
low complexity region 19 39 N/A INTRINSIC
transmembrane domain 57 79 N/A INTRINSIC
Pfam:SEA 88 191 3.2e-13 PFAM
CUB 341 452 3.82e-2 SMART
LDLa 457 489 1.33e-2 SMART
LDLa 490 527 2.31e-9 SMART
LDLa 530 568 1.07e-4 SMART
Tryp_SPc 576 806 3.75e-97 SMART
Predicted Effect probably null
Predicted Effect probably benign
Predicted Effect probably null
Predicted Effect probably null
Predicted Effect probably null
Meta Mutation Damage Score 0.9755 question?
Is this an essential gene? Probably nonessential (E-score: 0.067) question?
Phenotypic Category Autosomal Recessive
Candidate Explorer Status loading ...
Single pedigree
Linkage Analysis Data
Penetrance  
Alleles Listed at MGI

All Mutations and Alleles(13) : Chemically induced (ENU)(3) Gene trapped(2) Radiation induced(2) Targeted(6)

Lab Alleles
AlleleSourceChrCoordTypePredicted EffectPPH Score
IGL01066:Tmprss6 APN 15 78326634 missense probably null 1.00
IGL02474:Tmprss6 APN 15 78326536 missense probably damaging 0.99
cubone UTSW 15 78330857 splice site probably null
dilutional UTSW 15 78328328 missense probably damaging 1.00
mask UTSW 15 78464455 intron probably benign
masquerade UTSW 15 78352200 intron probably benign
zorro UTSW 15 78464552 intron probably benign
BB003:Tmprss6 UTSW 15 78337050 missense probably benign 0.28
BB013:Tmprss6 UTSW 15 78337050 missense probably benign 0.28
PIT1430001:Tmprss6 UTSW 15 78324827 missense probably damaging 1.00
R0285:Tmprss6 UTSW 15 78337068 missense probably damaging 0.99
R1857:Tmprss6 UTSW 15 78336752 missense probably damaging 1.00
R2432:Tmprss6 UTSW 15 78349304 splice site probably benign
R4192:Tmprss6 UTSW 15 78330857 splice site probably null
R4226:Tmprss6 UTSW 15 78330899 missense probably damaging 1.00
R4227:Tmprss6 UTSW 15 78330899 missense probably damaging 1.00
R4334:Tmprss6 UTSW 15 78343627 splice site probably null
R4344:Tmprss6 UTSW 15 78343627 splice site probably null
R4446:Tmprss6 UTSW 15 78337039 missense probably damaging 1.00
R4508:Tmprss6 UTSW 15 78343978 missense probably damaging 1.00
R4643:Tmprss6 UTSW 15 78329556 missense probably damaging 0.98
R4743:Tmprss6 UTSW 15 78327910 missense probably damaging 0.99
R4836:Tmprss6 UTSW 15 78329588 missense probably damaging 1.00
R4859:Tmprss6 UTSW 15 78330877 missense probably damaging 0.99
R4869:Tmprss6 UTSW 15 78327880 splice site probably null
R5197:Tmprss6 UTSW 15 78338389 missense probably damaging 1.00
R5212:Tmprss6 UTSW 15 78330460 missense probably damaging 0.99
R5225:Tmprss6 UTSW 15 78336707 missense probably damaging 0.97
R5569:Tmprss6 UTSW 15 78324503 missense probably damaging 1.00
R5572:Tmprss6 UTSW 15 78326622 missense probably damaging 1.00
R5669:Tmprss6 UTSW 15 78339156 missense possibly damaging 0.86
R5947:Tmprss6 UTSW 15 78336722 missense probably damaging 1.00
R6800:Tmprss6 UTSW 15 78324457 missense probably damaging 1.00
R6941:Tmprss6 UTSW 15 78330977 missense probably damaging 1.00
R6965:Tmprss6 UTSW 15 78328328 missense probably damaging 1.00
R7334:Tmprss6 UTSW 15 78328017 missense unknown
R7338:Tmprss6 UTSW 15 78344019 missense probably damaging 1.00
R7622:Tmprss6 UTSW 15 78330926 missense probably benign 0.40
R7926:Tmprss6 UTSW 15 78337050 missense probably benign 0.28
R7992:Tmprss6 UTSW 15 78326664 missense probably benign 0.11
R8177:Tmprss6 UTSW 15 78349327 missense probably benign 0.01
R8792:Tmprss6 UTSW 15 78328328 missense probably damaging 1.00
R8881:Tmprss6 UTSW 15 78327987 makesense probably null
R9084:Tmprss6 UTSW 15 78338417 missense probably damaging 0.98
R9384:Tmprss6 UTSW 15 78328302 missense probably damaging 0.99
X0025:Tmprss6 UTSW 15 78339295 missense possibly damaging 0.55
Mode of Inheritance Autosomal Recessive
Local Stock
Repository
Last Updated 2020-07-29 6:45 PM by External Program
Record Created 2015-12-31 7:58 AM by Carlos Reyna
Record Posted 2016-01-11
Phenotypic Description
Figure 1. Phenotype of the ekans mice.

The ekans phenotype was identified among G3 mice of the pedigree R4344, some of which showed body hair loss, but intact facial hair (Figure 1).

Nature of Mutation

Whole exome HiSeq sequencing of the G1 grandsire identified 35 mutations. Among these, only one affected a gene with known effects on hair loss, Tmprss6. The mutation in Tmprss6 was presumed to be causative because the cubone hair loss phenotype mimics other known alleles of Tmprss6 (see MGI for a list of Tmprss6 alleles as well as the mask (1), zorro, and masquerade strains from our lab). The Tmprss6 mutation is an A to T transversion at base pair 78,459,427 (v38) on chromosome 15, or base pair 133,970 in the GenBank genomic region NC_000081 for the Tmprss6 gene.

The effect of the mutation at the cDNA and protein level have not examined, but the mutation is predicted to result in skipping of the 178-base pair exon 10 (out of 18 total exons), resulting in an in-frame deletion of the 42-base pair exon 6, which encodes amino acid 206-219.

         <--exon 5          <--exon 6 intron 6-->         exon 7-->            <--exon 18

……GGCCTGGTGATCCTGG ……CTGAATTCCACGCTGG gtacgctgctctgtcct…… GCTGTTATCGC…… ……CAGGTGCTGACCTGA

……-G--L--V--I--L-- ……-L--N--S--T--L--                     G--C--Y--R-…… ……-Q--V--L--T--*-
      correct            deleted                                     correct

Genomic numbering corresponds to NC_000081. The donor splice site of intron 6, which is destroyed by the ekans mutation, is indicated in blue lettering and the mutated nucleotide is indicated in red. 

Illustration of Mutations in
Gene & Protein
Protein Prediction

Figure 3. Domain structure of TMPRSS6. The C-terminus of the protein, including the serine protease domain, is extracellular. Predicted N-glycosylation sites are noted in violet circles. The ekans mutation is within intron 6. This image is interactive. Click on the image to view other mutations found in TMPRSS6 (red). Click on the mutations for more specific information. 

Tmprss6 encodes an 811-amino acid protein of the type II transmembrane protease family (2). TMPRSS6, also known as matriptase-2, is predicted to contain a C-terminal trypsin-like serine protease domain (shown to be extracellular), three class A LDL receptor domains, two CUB domains (similar to a domain represented in BMP1 as well as C1R and C1S proteins), and a membrane-proximal SEA domain (Figure 3) (1;3)

Please see the record for mask for information about Tmprss6.

Putative Mechanism

The peptide hormone hepcidin, encoded by the Hamp gene, was identified as the major systemic iron regulator (4;5). TMPRSS6 is a non-redundant component in a pathway that senses iron deficiency and negatively regulates Hamp expression to promote iron uptake (1). TMPRSS6 proteolytic activity is critical for its Hamp-suppressing activity. Further study will be required to fully understand the mechanisms by which TMPRSS6 mediates Hamp inhibition and promotes iron uptake. The mechanism of hair loss in Tmprss6-mutant mice, including cubone, remains to be established, although severe iron deficiency is associated with hair loss in humans (6) and mice (7).

Primers PCR Primer
Ekans_pcr_F: AAGCACACGTCTACCTGAGC
Ekans_pcr_R: CCTGGAGCCAAGATAGAAGTC

Sequencing Primer
Ekans_seq_F: TACCTGAGCCCCCACCTG
Ekans_seq_R: CCAAGATAGAAGTCGAGGGC
Genotyping

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 425 nucleotides is amplified (chromosome 15, - strand):


1   cctggagcca agatagaagt cgagggcggg gacaggggca ggagcagggg cagggtgggt
61  gcagacagca tggagggctt acctctgctg agcctggctc ggcttctctc ccctgttttt
121 attttcgttg ttctattaat ttggctttgc ccttgtttat ttgtttgttc atttcctttt
181 gacagaagcc agtgtgaacg acatagtcgt actgaattcc acgctgggta cgctgctctg
241 tccttgtatt ggcctctttc ctttagaatc ataggtcttc ttgtctggtc cgttgtgggg
301 gtggaggtcc cgaggtgtcc actgtgggga cagggaaccc cagcttagaa acactggggg
361 gatctcagag ggtaatctgg gtgagggctc tgagcccagg tgggggctca ggtagacgtg
421 tgctt


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

References

1. Du, X., She, E., Gelbart, T., Truksa, J., Lee, P., Xia, Y., Khovananth, K., Mudd, S., Mann, N., Moresco, E. M., Beutler, E., and Beutler, B. (2008) The Serine Protease TMPRSS6 is Required to Sense Iron Deficiency. Science. 320, 1088-1092.

Science Writers Anne Murray
Illustrators Peter Jurek
AuthorsCarlos Reyna, Jamie Russell, and Bruce Beutler