Vitamin D-dependent rickets type IA / VDR (CYP27B1-related) - Cat

What does this test analyse?

This DNA test analyses the CYP27B1 variant c.637G>T in cats. The analysis covers vitamin D-dependent rickets type IA, also known as vitamin D-deficiency rickets, vitamin D-resistant rickets, pseudo-vitamin D-deficiency rickets, VDR and, in some descriptions, osteomalacia.

What does the disorder mean?

CYP27B1 encodes the enzyme needed to convert vitamin D into its biologically active form. Cats with two copies of the tested variant cannot form active vitamin D efficiently. This disrupts calcium balance and reduces proper mineralisation of bones and teeth.

• Clear: the tested variant was not detected.
• Carrier: one copy of the variant; the cat can pass it on.
• Genetically affected result: two copies of the variant; this causes hereditary vitamin D-dependent rickets type IA.

Practical value of this test

The result helps breeders identify carriers and avoid matings that can produce affected kittens. In kittens with matching signs such as abnormal bone development, pain sensitivity, poor mineralisation, delayed tooth development or pathological fractures, the test provides clear genetic information for this specific CYP27B1 variant.