Norwich DNA health tests

There are currently five DNA health tests that are relevant for Norwich terriers. Four are currently available commercially. All of these tests are inexpensive and require nothing more than a swab of the inside of a dog's mouth in order to get a DNA sample to test.

PLL

Primary lens luxation (PLL) is an eye disease found mostly in the terrier breeds . Some Norwich have been diagnosed with PLL. These Norwich and related Norwich have been found to carry the mutation in the ADAMS17 gene believed to be the cause of PLL and diagnosed by the PLL DNA test. Many commercial labs offer the PLL DNA test.

DM

Degenerative Myelopathy (DM) is an adult-onset, progressive spinal cord disease causing weakness in the hind limbs and eventually paralysis. Because common spinal cord injuries can mimic DM, a definitive diagnosis can only be made by a postmortem examination of the spinal cord. No Norwich has been definitively diagnosed with DM. A veterinary neurologist reported a Norwich with DM, but unfortunately the spinal cord was not postmortemly examined.

A mutation in the SOD1 (exon2) gene has been associated with DM. This mutation has been found in over 100 breeds, and is believed to be an ancesteral mutation predating the segretation of dogs in breeds. This mutation exists in Norwich terriers. Many commercial labs offer the DM DNA test.

DNA testing for DM has generated controversy.

Some argue that since no Norwich has been definitively diagnosed with DM, that there are modifier genes that stop Norwich from getting DM. However no evidence has been presented that such modifier genes exist for Norwich nor has any search been made for modifier genes among Norwich. A 2016 paper reported that a modifier gene had been found in Pembroke Welsh Corgies.

ALT

Alanine aminotransferase, or ALT, is a common value on most blood chemistry panels and is known to be a sensitive measure of liver health. Labs give a reference range for normal ALT values. This reference value was determined from the ALT results of lots of healthy dogs of many breeds.

Dogs with one or two copies of an ALT mutation may have "low-normal" ALT activity. This is not a disease state. Rather it is a clinical finding - dogs with low-normal ALT activity have lower resting levels of ALT activity. In other words, the reference range for dogs with the ALT mutation is different (lower) than for the general dog population. This means that if the ALT activity rose, it still could fall within the range the lab reports as normal and might be missed by a veterinarian who was not aware that the dog is a "low-normal".

Th low-normal ALT mutation has been seen in several Norwich who are not closely related. The only DNA lab offering to test for the ALT mutation is Embark, as part of their DNA panel test. (Their panel also tests for PLL and DM, along with over 160 other DNA health tests.)

INPP5E

In September 2018, Finnish researchers published a paper reporting on a mutation in the INPP5E gene that causes kidney failure and death in Norwich terrier puppies. While this mutation was discovered among Finnish Norwich terriers, the mutation is known to exist among North American Norwich.

The only lab in North America currently offering a DNA test for the INPP5E mutation is a genetics lab at North Carolina State University. To test, one starts by ordering a (free) cheek swab kit.

UAS

In May 2019, European researchers published a paper reporting on an association between a mutation in the ADAMTS3 gene and Norwich Terrier Upper Airway Syndrome (NTUAS). Currently no commercial lab is offering a DNA test for this mutation.

Last updated 20190725