Dilute Gen: Color Dilution Alopecia (CDA) beim Hund | Blue Line
In this article we would like to inform you about the dilute gene and colour dilution alopecia (CDA for short). In cooperation with Dr Patrick Hensel from Animal Dermatology Basel, we have summarised the most important questions in the form of an interview and would like to provide you with correct information with the help of an animal dermatology expert.
What is the dilute gene?
Die Haut- und Fellfarbe des Hundes wird durch 2 Melanintypen bestimmt. Das Eumelanin erzeugt eine schwarze bis dunkelbraune Farbe, während Pheomelanin eine rot/gelb Färbung bewirkt. Zudem gibt es noch weitere Gene in verschiedenen Bereichen, die man Loci nennt, die die Verteilung des Melanins bestimmen. So gibt es z. B. S-Locus (weisse Flecken im Fell), M-Locus (Merle Fell), K-Locus (dominantes Schwarz), D-Locus (Dilution), etc. Das Dilute Gen ist somit ein Gen, das es bereits sehr lange gibt und eine Farbvariation darstellt. Fälschlicherweise wird das Dilute häufig als "Gendefekt" betitelt, was vollkommen falsch ist. Dilute ist wie Merle und Co. eine Farbvariation. Ehrlicherweise muss man sagen, dass auch die Wissenschaft noch nicht endgültige Erkenntnisse hinsichtlich des Dilute Gens liefern kann. Viele Genetiker und Veterinärmediziner arbeiten deshalb intensiv an der Forschung. Zurzeit geht man davon aus, dass es sich um das Gen handelt, welches für die Produktion von Melanophilin (MLPH) verantwortl
How does the dilute gene come about?
We don't want to go that deep into genetics, but a little school knowledge from biology lessons is required 🙂
If we look at a chromosome gene pair, it consists of two alleles. Locus represents the physical location where a particular gene is located, the location of the gene, so to speak. If we think back to Mendel' s laws for a moment, we remember that there arerecessive or dominant colours in relation to the colour , for example. This means that dominant colours are more likely to be passed on than recessive colours. So if the seeds of a red rose (R / dominant) are mixed with those of a white rose (r / recessive), the following colour variations can result:
- Genotype: RR and the rose turns red,
- as with the genetic combination of Rr, because in this case the rose will also be phenotypically red, as red is the dominant gene,
- only with genotype rr the rose becomes phenotypically white.
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Which animals are affected?This colour dilution exists in many different species and is also found in a whole range of dog breeds. A classic example would be the Weimaraner and Slovakian Pointer, which are only with dilute colours. Then there are dog breeds in which it is relatively common (Italian Greyhounds, Whippets, Tibetan Mastiffs and Neapolitan Mastiffs). Then there are a whole range of dogs in which the dilute gene is rare, but has recently become more and more popular due to the trend (e.g. American Staffordshire Terrier, Great Dane, Shar-Pei, Labrador, French Bulldog, etc.). |
Dilute gene and CDA disease
Dilute ist kein Gendefekt, wie es immer wieder gerne, aber fälschlicherweise verbreitet wird, sondern eine Farbvariation, die in der Regel zu keinen weiteren Problemen führt. Aufgrund der erhöhten Nachfrage in den vergangenen Jahren, kam es zu einer Krankheit, die mit dem Dilute Gen assoziiert wird und unter dem Namen Color Dilution Alopecia (kurz: CDA) bekannt ist. Bei CDA leiden die Hunde unter starken Hautproblemen, Fellausfall und Juckreiz. Die Haut verkrustet und die Lebensqualitäte des Hundes lässt nach. Die Gründe, die zu einer Erkrankung an CDA führen, sind noch nicht bekannt. Tatsächlich entwickeln nicht alle Hunde mit Farbverdünnung (also Dilute Gen) Probleme. Grösstenteils führt das Dilute Gen nicht zu CDA, jedoch ist beim Dobermännern und einigen anderen Rassen bekannt, dass es besonders häufig eine Verknüpfung von CDA und dem Dilute Gen gibt.
In fact, there are many breeds that are bred exclusively in the Dilute colours and have had no demonstrable problems for generations (for example, the Weimeraner). However, more and more grey or isabella / lilac-coloured dogs are becoming ill with CDA. The causes are not yet entirely clear. The problem should be taken seriously, and the breeding and choice of dog should be considered first and foremost. An important indicator can be the breeding itself. Especially in recent years, the demand for grey dogs has increased extremely and many questionable dog sellers are wandering around on eBay classifieds, offering almost exclusively grey dogs. Most of the sellers have no idea about genetic processes and experiment at the expense of dog health. Dogs from non-reputable sources and untraceable breeding can then fall ill with CDA more frequently.
The fact that the dilute colours only pose a minimal to no health risk in a few seriously bred dogs points to other, as yet unexplored, causes. Researchers currently suspect that CDA only occurs with a large number of other mutations. With selected breeding, the probability of puppies contracting CDA is very low.
There are now several scientific texts that deal with CDA and Dilute. If you are interested in reading more, have a look here:
- Polymorphisms within the canine MLPH gene are associated with dilute coat color in dogs: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1183202/
- Color dilution alopecia in a blue Doberman pinscher crossbreed: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2671874/
- Color–dilution alopecia in dogs: https://www.ncbi.nlm.nih.gov/pubmed/16131833
- A Noncoding Melanophilin Gene (MLPH) SNP at the Splice Donor of Exon 1 Represents a Candidate Causal Mutation for Coat Color Dilution in Dogs: https://academic.oup.com/jhered/article/98/5/468/2187775
- Chromosomal Assignment of the Canine Melanophilin Gene (MLPH): A Candidate Gene for Coat Color Dilution in Pinschers: https://academic.oup.com/jhered/article/96/7/774/2187651
