Phenotypic Mutation 'splinter' (pdf version)
Allelesplinter
Mutation Type nonsense
Chromosome5
Coordinate98,409,846 bp (GRCm39)
Base Change C ⇒ T (forward strand)
Gene Fgf5
Gene Name fibroblast growth factor 5
Synonym(s) Fgf-5
Chromosomal Location 98,402,108-98,424,892 bp (+) (GRCm39)
MGI Phenotype FUNCTION: This gene encodes a secreted protein that is a member of a family of heparin-binding growth factors. The encoded protein regulates cell proliferation, particularly the growth of hair follicles. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Mar 2013]
PHENOTYPE: Mutations in this gene result in significantly longer pelage hair. [provided by MGI curators]
Accession Number

Ncbi Refseq: NM_010203.5; NM_001277268.1; MGI: 95519

MappedYes 
Amino Acid Change Arginine changed to Stop codon
Institutional SourceBeutler Lab
Gene Model predicted gene model for protein(s): [ENSMUSP00000031280] [ENSMUSP00000142420]
AlphaFold P15656
SMART Domains Protein: ENSMUSP00000031280
Gene: ENSMUSG00000029337
AA Change: R132*

DomainStartEndE-ValueType
signal peptide 1 20 N/A INTRINSIC
low complexity region 34 72 N/A INTRINSIC
FGF 83 217 3.78e-77 SMART
low complexity region 231 244 N/A INTRINSIC
Predicted Effect probably null
SMART Domains Protein: ENSMUSP00000142420
Gene: ENSMUSG00000029337

DomainStartEndE-ValueType
signal peptide 1 20 N/A INTRINSIC
low complexity region 34 72 N/A INTRINSIC
Pfam:FGF 85 120 5.6e-7 PFAM
Predicted Effect probably benign
Meta Mutation Damage Score 0.9755 question?
Is this an essential gene? Probably nonessential (E-score: 0.124) question?
Phenotypic Category Autosomal Recessive
Candidate Explorer Status loading ...
Single pedigree
Linkage Analysis Data
Penetrance  
Alleles Listed at MGI

All alleles(5) : Targeted(2) Spontaneous(2) Chemically induced(1)

Lab Alleles
AlleleSourceChrCoordTypePredicted EffectPPH Score
IGL01305:Fgf5 APN 5 98423175 missense probably damaging 1.00
IGL02037:Fgf5 APN 5 98409831 missense probably damaging 1.00
IGL02125:Fgf5 APN 5 98402391 missense possibly damaging 0.55
IGL02926:Fgf5 APN 5 98409874 missense probably damaging 0.99
porcupine UTSW 5 98402604 missense probably damaging 1.00
ANU22:Fgf5 UTSW 5 98423175 missense probably damaging 1.00
PIT4472001:Fgf5 UTSW 5 98409838 missense probably damaging 1.00
R0090:Fgf5 UTSW 5 98409846 nonsense probably null
R2146:Fgf5 UTSW 5 98423409 makesense probably null
R5023:Fgf5 UTSW 5 98409874 missense probably damaging 0.99
R6035:Fgf5 UTSW 5 98423385 missense probably damaging 1.00
R6035:Fgf5 UTSW 5 98423385 missense probably damaging 1.00
R8997:Fgf5 UTSW 5 98423411 makesense probably null
R9766:Fgf5 UTSW 5 98423113 missense possibly damaging 0.49
X0018:Fgf5 UTSW 5 98402295 missense unknown
Mode of Inheritance Autosomal Recessive
Local Stock Live Mice
MMRRC Submission 036924-MU
Last Updated 2016-12-08 2:04 PM by Anne Murray
Record Created 2012-12-28 1:31 PM by Tiana Purrington
Record Posted 2014-03-28
Phenotypic Description
Figure 1. Image of a splinter mouse. The splinter mice have longer fur and tufts of white fur behind their ears.

The splinter phenotype of abnormally long pelage hair was identified among G3 mice carrying homozygous ENU-induced mutations (Figure 1). Transmissibility of the phenotype was confirmed by phenotypic reoccurrence in siblings from the same parental breeding pair.

Nature of Mutation

Whole exome HiSeq sequencing of the G1 grandsire identified 79 mutations. Three mice with the splinter phenotype were genotyped at the Fgf5 locus; the mutation in Fgf5 was presumed to be causative because the splinter phenotype mirrored the porcupine phenotype attributed to a mutation in Fgf5. Subsequent analysis of one additional affected mouse and nine unaffected mice supported a causal relationship between the mutation and the phenotype (LOD = 5.167). Capillary sequencing of the mutated gene identified a C to T transition at base pair 98261987 (v38) on chromosome 5 in the GenBank genomic region NC_000071 encoding Fgf5. The mutation corresponds to residue 394 in the mRNA sequence in exon 2 of 3 total exons.

382 ATTGTAGGAATACGAGGAGTTTTCAGC
128 -I--V--G--I--R--G--V--F--S-

The mutated nucleotide is indicated in red.  The mutation results in a substitution of arginine (R) to a premature stop codon at residue 132, and may cause nonsense-mediated decay of the transcript.

Illustration of Mutations in
Gene & Protein
Protein Prediction

Figure 2. Domain structure of FGF5 and FGF5s. (A) The canonical FGF5 isoform has 12 highly conserved core regions containing residues and structural motifs common to all FGF family members. These beta sheet regions are shown by green bars 1-12. Additional receptor binding regions and ligand binding sites are indicated by the colored bars above as described in the key. (B) The less common truncated FGF5s isoform has a 4 aa area deleted within the FGF domain. The splinter mutation results in coding of a premature stop codon at residue 132, and is shown by the red asterisk. Image is interactive, click to see another Fgf5 mutation.

The splinter mutation creates a stop codon in place of arginine at position 132 of Fgf5 within the internal core region responsible for ligand-receptor specificity (Figure 2)

Please see the record for porcupine for more information about Fgf5.

Putative Mechanism

Similar to the porcupine mutant, the splinter mutation results in abnormally long hair.  The role of FGF5 in the hair cycle has been documented to promote the transition from anagen VI to catagen (1).

Primers PCR Primer
splinter_pcr_F: ACACGTTGGAGGTCACAAAAGGTC
splinter_pcr_R: AGAAATGCCCCTGCTTCCTCAAG

Genotyping

Splinter genotyping is performed by amplifying the region containing the mutation using PCR, followed by sequencing of the amplified region to detect the single nucleotide change.  The following primers are used for PCR amplification:

Primers for PCR amplification

Splinter(F):  5’- ACACGTTGGAGGTCACAAAAGGTC -3’

Splinter(R):  5’- AGAAATGCCCCTGCTTCCTCAAG -3’

Primers for sequencing

Splinter_seq(F):  5’- AGGTCACAAAAGGTCATTATATGTTC -3’

PCR program

1) 94°C        2:00

2) 94°C        0:30

3) 57°C        0:30

4) 72°C        1:00

5) repeat steps (2-4) 29x

6) 72°C        7:00

7) 4°C            ∞

The following sequence of 772 nucleotides (from Genbank genomic region NC_000071 for linear DNA sequence of Fgf5) is amplified:

7609                                                     ac acgttggagg

7621 tcacaaaagg tcattatatg ttcttttatt taatctcagt agtaaggact gagaacagtt

7681 gacgtagtag acattgaatt cttcacagtt ctgtgtagaa gagtctgtgt tttattttgg

7741 gatttttttg tcatcctagg tattttggaa atatttgctg tgtctcaggg gattgtagga

7801 atacgaggag ttttcagcaa caaattttta gcgatgtcaa aaaaaggaaa actccatgca

7861 agtgtaagta gaaacccctt tgtgtttgtt gaaaagtgct ccaccggttg tgcgtctgta

7921 acaaagtgaa gagattgttt ttgaaatgag tggataagat agaccatttg cctaaggaac

7981 ttatttggtt tttttctggt aaaaatgata tgtatgtata accaattgtg aatctgtctg

8041 taagtcatta ttggaacatg tctttgtttt ggaaacaaat agaaccttca aggctgtaaa

8101 gggtaaatgc acttgtaaac agcctttgca aacggattgc cattgtgaga cttgtcacag

8161 gagtgagcta ttccgtggcc tcacataaac tttacatttg gtggcatgtg tgtttaatag

8221 acagaggggt tcttaattga ttttacagat tactcatgat attaatttga ggtctaagta

8281 atatatgttt ccatgtaagg aagtaaagga caaaagcgac acccgccaag cctctcacct

8341 cccagagaga aactgtgctt gaggaagcag gggcatttct

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

References
Science Writers Anne Murray
Illustrators Peter Jurek
AuthorsTiana Purrington