Microphthalmia with haematopoietic defects (DNAJC21-related) - Portuguese Water Dog

What does this test analyse?

This genetic test analyses a DNAJC21 SINE insertion in the Portuguese Water Dog. The condition is named microphthalmia, canine congenital microphthalmos with haematopoietic defects and DNAJC21-related microphthalmia.

DNAJC21 belongs to the HSP40 protein family and is involved in ribosome formation and protein processing. The insertion disrupts gene function and is linked to a syndromic condition involving eyes, blood formation, growth and teeth.

What does this condition mean?

Affected dogs can have clearly reduced eye size on one or both sides, sometimes with cataract, corneal abnormalities, microphakia or absent lens, glaucoma, retinal abnormalities and persistent pupillary membranes. Outside the eye, anaemia, thrombocytopenia, stunted growth, delayed tooth eruption and enamel defects can occur.

Inheritance and result

The trait is inherited as autosomal recessive. One copy makes a dog a carrier; two copies cause the genetically affected genotype.

Practical value of this test

• The test distinguishes clear dogs, carriers and dogs with the relevant genetic risk genotype.
• The result helps breeders plan matings deliberately and avoid risk pairings.
• Variant status can be documented clearly within lines, families and breeding advice.
• The test helps breeders identify carriers before two carriers are paired.
• Because the condition affects several body systems, a DNA result gives early clarity about a serious inherited disorder.
• For Portuguese Water Dogs, the test supports targeted selection against both eye abnormalities and blood-formation problems.

This test assesses the known DNAJC21 insertion. Other causes of small eyes, cataract or blood abnormalities fall outside this specific variant analysis.