Chinese Hamster Genetics

Like all animals, Chinese hamsters are made up of cells containing genetic material which they have inherited from their parents. This genetic material affects their appearance, health and behaviour.

The genetic material, DNA, is made into individual blocks of information, or genes. A collection of genes is known as a chromosome. Chinese hamsters have 22 chromosomes.

Genes provide information to the cell about building a specific feature, such as coat pattern. The gene for the dominant spot pattern sits at on a specific area of the chromosome. Each area can contain only one gene for that feature, i.e. either a ‘spotty’ (Ds) or a ‘non-spotty’ (ds) gene.

Chromosomes come in pairs, so each cell has two genes for coat pattern, one on each chromosome. They can be different (one spotty and one non-spotty) or the same (two spotties or two non-spotties).

Some genes alter the hamster’s appearance only when they are present on both chromosomes. This is referred to as a recessive gene. The gene code for a recessive gene is traditionally written in lowercase letters. In Chinese hamsters, the normal colour (or ‘non-spotty’) is a recessive gene, meaning that a hamster has to have two copies to be normal coloured.

Other genes alter the hamster’s appearance when they are present on only one chromosome. This is referred to as a dominant gene and the gene code for a dominant gene is traditionally written in uppercase letters. In Chinese hamsters, the dominant spot pattern (or ‘spotty’ as I have been referring to it) is a dominant gene, meaning that a hamster only needs one copy for it to have a dominant spot pattern.

A Chinese hamster receives one of each chromosome pair from each parent in the egg and sperm (also called gametes). The egg and sperm have half the number of chromosomes as the other body cells so that when they join to create the offspring, the offspring has the correct total of 22 .

What are the Chances?

If you pair two Chinese hamsters, what are the likely colours you will see in the litter?

Both normal parents: 100% normal

One normal and one dominant spot parent: 50% normal and 50% dominant spot

Both dominant spot parents (from BEW lines): 25% normal, 50% dominant spot and 25% black eyed white

Both dominant spot parents (not BEW lines): 33% normal and 66% dominant spot in a smaller litter

One normal and one black eyed white parent: 100% dominant spot

One dominant spot (from BEW lines) and one black eyed white parent: 50% dominant spot and 50% black eyed white

These are probabilities of what to expect in a litter. What proportions you actually get in a specific litter are not guaranteed. Chinese hamster genetics can be frustrating even when the odds are in your favour!