Update on CHG

DNA Test for Congenital Hypothyroidism with Goiter (CHG)

What is this test for?

The test detects the presence of the gene mutation that causes CHG in Tenterfield terriers. It is not the same test as for toy fox or rat terriers. Mutation based DNA tests are breed-specific.

Using the test, it is possible to identify dogs that are:

• affected with CHG (affected individuals have two copies of the mutant gene), although the disease is clinically obvious.
• carriers of CHG (have one copy of the mutant gene and one normal gene copy). Carriers do not develop the disease themselves but can pass the gene mutation on to the next generation.
• genetically normal for CHG (have two copies of the normal gene and cannot pass the mutation to subsequent offspring).

How accurate is the test?

The test detects the actual disease-causing mutation and is therefore 100% reliable in identifying this form of CHG. If, however, a second form of hypothyroidism were to develop in this breed, the test would not be able to identify it. However, the test is only as accurate as the sample collection. Please take every care to follow the submission instructions and ensure that the brushes or blood tubes are labeled correctly.

How do I collect brush or swab samples for testing?

To collect samples for this test, the following procedure should be followed carefully:

Procedure:

1. We advise that two people collect the DNA sample, one to gently restrain and hold the head, the second to collect the sample. To avoid contamination from dog food, please collect the sample at least 2 hours after the last meal or snack. Dogs may have access to water at any time.
2. Label each brush sleeve with the dog’s full name, registration number and owner’s name. Label 2 brushes per dog. Label on the paper side of the brush sleeve (labels on the plastic side come off too easily).
3. Wash hands before sample collection and between dogs if more than one DNA sample is being collected. We are more interested in the dog’s DNA than yours.
4. Peel open the brush package about 1 inch at the arrow (the opposite end from the bristles). Remove the brush, being careful not to touch the bristles.
5. Place the brush between the lip and gum of the dog being tested, and gently brush the inside of the cheek using all sides of the round brush.
6. Place the brush back in the original labeled package, bristles in first, and tape the ends of each brush packet closed.
7. Repeat steps 3-6 with the additional brush for each dog. Please collect 2 brushes from each dog.

How do I collect blood samples for testing ?

Submit 0.2-0.4 cc of whole blood in EDTA anticoagulant (purple top tube). If not sent immediately, refrigerate (do not freeze). When mailed, no ice packs or other cooling is needed, but be sure to pad each tube to avoid breakage.

Cost and mailing

The test fee is $65.00 per dog. We will supply brushes for sampling (an additional $5.00) if you communicate your postal mailing address and the number of dogs to test. Please enclose an international money order for the total in US dollars made out to: Michigan State University (CHG Test), and include it with the samples. We have no arrangements for electronic payment. For shipment, bundle the brushes for each animal, and returned all in the same package. Blood tubes should be padded. Samples are stable without refrigeration. Include in the package:

1. clearly labeled brushes or blood tubes (please use registered names and registration numbers, if available)
2. full payment, including for brushes sent to you
3. pedigrees of the dogs submitted (optional, but appreciated)

The attached form can be used to submission information

The package should be sent by Priority Mail to:

John C. Fyfe, DVM, PhD

Laboratory of Comparative Medical Genetics

2209 Biomedical Physical Sciences Bldg

Michigan State University

East Lansing, MI 48824-4320

How will I be informed of the result?

Result(s) certificates will be mailed to you using the return address that you supplied. We do not give out results over the telephone, but we will email if an E-address is provided. Communication with the laboratory is most efficient by email. All results are strictly confidential and will only be released to the person who submitted the samples.