Editing Scottish Fold (section)

==Genetics==
An early study suggested that the fold is inherited as an autosomal dominant trait.<ref name="AustraliaVetJournal" /> A later study suggested an [[Autosomal dominant#Incomplete dominance|incomplete dominance]].<ref>{{cite journal |date=April 2008 |title=Incomplete dominant osteochondrodysplasia in heterozygous Scottish Fold cats |journal=The Journal of Small Animal Practice |url= https://pubmed.ncbi.nlm.nih.gov/18339089/ |volume=49 |number=4 |pages=197–9 |doi=10.1111/j.1748-5827.2008.00561.x |last1=Takanosu |first1=M. |last2=Takanosu |first2=T. |last3=Suzuki |first3=H. |last4=Suzuki |first4=K. |pmid=18339089}}</ref> A cat with folded ears may have either one ([[Zygosity|heterozygous]]) or two copies (homozygous) of the dominant fold gene (Fd). A cat with normal ears should have two copies of the normal gene (fd).

{| class="wikitable" style="text-align: center; "
|-
| colspan="2" rowspan="2" |
! colspan="2" | Homozygous fold
|-
! Fd || Fd
|-
! rowspan="2" | Homozygous fold
! Fd
| Fd Fd || Fd Fd
|-
! Fd
| Fd Fd || Fd Fd
|}

{| class="wikitable" style="text-align: center; "
|-
| colspan="2" rowspan="2" |
! colspan="2" | Heterozygous fold
|-
! Fd || fd
|-
! rowspan="2" | Homozygous fold
! Fd
| Fd Fd || Fd fd
|-
! Fd
| Fd Fd || fd Fd
|}

{| class="wikitable" style="text-align: center; "
|-
| colspan="2" rowspan="2" |
! colspan="2" | Straight-eared
|-
! fd || fd
|-
! rowspan="2" | Homozygous fold
! Fd
| Fd fd || Fd fd
|-
! Fd
| Fd fd || Fd fd
|}

Mating a homozygous fold with any cat will produce all folds, but because homozygous folds are prone to severe health issues, breeding for them is generally considered unethical. A homozygous to normal mating will produce only heterozygous folds but presumably in ethical breeding programs, there will be no homozygous cats available to breed from.

{| class="wikitable" style="text-align: center; "
|-
| colspan="2" rowspan="2" |
! colspan="2" | Straight-eared
|-
! fd || fd
|-
! rowspan="2" | Heterozygous fold
! Fd
| Fd fd || Fd fd
|-
! fd
| fd fd || fd fd
|}
The only generally accepted breeding gives a 50% chance of producing heterozygous folds and 50% chance of producing progeny with normal genes.

{| class="wikitable" style="text-align: center; "
|-
| colspan="2" rowspan="2" |
! colspan="2" | Heterozygous fold
|-
! Fd || fd
|-
! rowspan="2" | Heterozygous fold
! Fd
| Fd Fd || Fd fd
|-
! fd
| fd Fd || fd fd
|}

There is suspicion that some non-fold litters are genetically heterozygous folds but because of very low expression of the gene, appear to be straight-eared. Such kittens may develop folded ears initially which then straighten back out. Because of this there are suggestions by some breeders to avoid mating Folds with straight-eared Scottish Folds but only use British Shorthairs (BSH) as [[Outcrossing|outcross]].<ref name="nzcfecmeeting" /><ref>{{cite web |last=Sutton |first=Grace |title=Breed Article: Scottish Folds |url=http://cfa.org/Breeds/BreedsSthruT/ScottishFold/SFArticle.aspx |website=cfa.org |publisher=[[Cat Fanciers' Association]] |access-date=7 December 2013 |archive-date=2 December 2013 |archive-url=https://web.archive.org/web/20131202233621/http://www.cfa.org/Breeds/BreedsSthruT/ScottishFold/SFArticle.aspx |url-status=dead }}</ref> If Scottish Shorthairs are to be used, they should be test mated to a BSH to make sure that they are not genetically folds.<ref name="nzcfecmeeting" /> If such apparent straight-eared cats are mated with a fold, there is a 75% chance of folds (25% homozygous folds, 50% heterozygous folds) and 25% chance of straight ears.

In 2016, the [[Mutation|genetic mutation]] responsible for the folded ears and the [[osteochondrodysplasia]] was identified. It was found in a gene encoding a calcium permeable ion channel, transient receptor potential cation channel, subfamily V, member 4 (''Trpv4'').<ref>{{Cite journal |pmid=27063440 |date=2016 |last1=Gandolfi |first1=B. |last2=Alamri |first2=S. |last3=Darby |first3=W.G. |last4=Adhikari |first4=B. |last5=Lattimer |first5=J.C. |last6=Malik |first6=R. |last7=Wade |first7=C.M. |last8=Lyons |first8=L.A. |last9=Cheng |first9=J. |last10=Bateman |first10=J.F. |last11=McIntyre |first11=P. |last12=Lamandé |first12=S.R. |last13=Haase |first13=B. |title=A dominant TRPV4 variant underlies osteochondrodysplasia in Scottish fold cats |journal=[[Osteoarthritis and Cartilage]] |volume=24 |issue=8 |pages=1441–50 |doi=10.1016/j.joca.2016.03.019 |doi-access=free}}</ref> The mutation is a V342F substitution (c.1024G>T) in the fifth ankyrin repeat within the N-terminal cytoplasmic domain. It was also found in a human patient with [[Kniest dysplasia|metatropic dysplasia]].<ref>{{Cite journal |pmid=20577006 |date=2010 |last1=Dai |first1=J. |last2=Kim |first2=O.H. |last3=Cho |first3=T.J. |last4=Schmidt-Rimpler |first4=M. |last5=Tonoki |first5=H. |last6=Takikawa |first6=K. |last7=Haga |first7=N. |last8=Miyoshi |first8=K. |last9=Kitoh |first9=H. |last10=Yoo |first10=W.J. |last11=Choi |first11=I.H. |last12=Song |first12=H.R. |last13=Jin |first13=D.K. |last14=Kim |first14=H.T. |last15=Kamasaki |first15=H. |last16=Bianchi |first16=P. |last17=Grigelioniene |first17=G. |last18=Nampoothiri |first18=S. |last19=Minagawa |first19=M. |last20=Miyagawa |first20=S.I. |last21=Fukao |first21=T. |last22=Marcelis |first22=C. |last23=Jansweijer |first23=M.C. |last24=Hennekam |first24=R.C. |last25=Bedeschi |first25=F. |last26=Mustonen |first26=A. |last27=Jiang |first27=Q. |last28=Ohashi |first28=H. |last29=Furuichi |first29=T. |last30=Unger |first30=S. |title=Novel and recurrent TRPV4 mutations and their association with distinct phenotypes within the TRPV4 dysplasia family |journal=[[Journal of Medical Genetics]] |volume=47 |issue=10 |pages=704–9 |doi=10.1136/jmg.2009.075358 |s2cid=925054 |url= https://pure.uva.nl/ws/files/1257940/93555_339667.pdf}}</ref>