UC Davis School of Veterinary Medicine Veterinary Genetics Laboratory
Burmese Genetic Tests

Burmese Head Defect

Congenital frontonasal dysplasia in Burmese cats, commonly known as Burmese Head Defect (BHD), is a genetic defect that causes disruption of the normal developmental processes that form the skull and facial features in the fetus. In affected cats, this defect causes duplication of the tissue of the upper jaw, development of two hard palates (the bony roof of the mouth) and of two sets of whisker pads. In addition, the skull above the upper jaw does not form properly, eyes and ears are absent or malformed, and the fontanelles of the skull do not close completely. These head malformations are extreme and present at birth. If born alive, affected kittens require immediate euthanasia as the condition is incompatible with life.


The molecular basis of BHD was identified as a deletion of 12 base pairs in the Aristaless-Like Homeobox 1 (ALX1) gene. This gene plays a critical role in the regulation of development and survival of structural elements of the face and neck in growing fetuses. BHD was originally observed in the Contemporary lines of Burmese cats in the United States. While introduced by a single, prolific male cat that was the progenitor of the Contemporary line of Burmese cats, the BHD mutation has also been identified in Bombay and Tonkinese cats.


BHD is inherited in a co-dominant fashion. One copy of the mutation does not cause BHD but may produce a shortened facial structure (brachycephaly), which is considered a desirable trait in the breed. Cats with two copies of the mutation have the severe craniofacial defect that is incompatible with life.


The VGL offers a DNA test for Burmese Head Defect that assists veterinarians by providing positive confirmation of BHD diagnosis in Burmese and related cats born with craniofacial malformation.  It also assists owners and breeders in identifying affected and carrier cats. Breeders can use test results as a tool to avoid breeding carriers together because from these matings 25% of kittens are expected to be affected.

Testing is recommended for Burmese, Bombay and Tonkinese cats and their crossbreds.

Procedure for collecting a feline DNA sample

ORDER TEST KITS | PRICE LIST
Allow 2-6 business days for results.

Results reported as:

Test Result

Burmese Head Defect

N/N

Normal, cat does not have Burmese Head Defect mutation

N/BHD

Carrier, cat has one copy of Burmese Head Defect mutation. In breedings between carriers, 25% of kittens are expected to be affected.

BHD/BHD

Affected

Burmese Head Defect is not related to Midline Defect, a genetic disease which can present head malformation among other abnormalities. Midline Defect appears more common in European lines of Burmese cats and is currently under investigation. No genetic test is available at this time for Midline Defect.

Reference:
Lyons LA, Erdman CA, Grahn RA, Hamilton MJ, Carter MJ, Helps, CR, Alhaddad H, Gandolfi B. (2016) Aristaless-Like Homeobox protein 1 (ALX1) variant associated with craniofacial structure and frontonasal dysplasia in Burmese cats. Dev Biol.  Jan 15; 409(2): 451–458 doi: 10.1016/j.ydbio.2015.11.015.

Burmese Hypokalemia

Burmese Hypokalemia, also known as Familial Episodic Hypokalaemic Polymyopathy, is a recessive genetic defect characterized by episodes of low serum potassium levels and high CPK (creatine phosphate kinase, an enzyme that indicates muscle damage). Clinical signs include episodes of skeletal muscle weakness which can affect the whole animal or may be restricted to certain muscles. This is most obvious in the neck muscles, but sometimes occurs in just the limbs. As a result affected cats may show problems with walking and holding their head correctly. The disease is not typically fatal and affected cats usually can be managed by adding potassium supplements to their diet. For specifics on management of this condition, owners are urged to consult with their veterinarian.

Breeds that are at risk for this disease include: Burmese and outcrosses such as Burmilla, Bombay, Cornish Rex, Devon Rex, Singapura, Sphynx, Australian Mist, Tiffanie, and Tonkinese.

The genetic mutation responsible for this disease has been identified by a team of researchers from the University of Bristol (England), the Lyons Feline Genetics Research Laboratory at UC Davis, University of Sydney, Massey University and Justus Liebig University. This discovery has allowed development of a genetic test that allows identification of carrier and affected cats.

The VGL offers the DNA test for Burmese Hypokalemia to assist owners and breeders in identifying affected and carrier cats. The tests are done with DNA collected from buccal swabs thus avoiding invasive blood collection. Breeders can use these tests as a tool to avoid breeding carriers together which would produce 25% affected offspring.

Procedure for collecting a feline DNA sample

ORDER TEST KITS | PRICE LIST
Allow 2-6 business days for results..

Results reported as:

Test Result Burmese Hypokalemia
N/N Normal, cat does not have Burmese Hypokalemia mutation
N/BHK

Carrier, cat has one copy of Burmese Hypokalemia mutation. Breedings between carriers are expected to produce 25% affected kittens.

BHK/BHK Affected

 

GM2 Gangliosidosis

GM2 gangliosidosis is a degenerative, fatal neurological disease characterized by severe muscle tremors and loss of motor control. In Burmese cats, the disease is caused by a mutation in the feline hexoaminadase β-subunit (HEXB) gene which leads to abnormal swollen neurons and brain lesions. The inherited condition in affected kittens is first observed at 6-8 weeks of age beginning with mild tremors and leading to difficulty eating and lack of coordination. The condition is inherited as a recessive, autosomal disorder.

Procedure for collecting a feline DNA sample

ORDER TEST KITS | PRICE LIST
Allow 2-6 business days for results.

Results reported as:

Test Result GM2 Gangliosidosis Status
N/N Normal, cat does not have GM2 Burmese mutation*
N/GM2 Carrier, cat has one copy of GM2 Burmese mutation. Breedings between carriers will be expected to produce 25% affected kittens.
GM2/GM2 Affected

* This test is specific for the 15 base pair deletion of HEXB found in Burmese cats and will not detect other HEXB mutations known to exist in other breeds of cats.

References:

Bradbury AM, Morrison NE, Hwang M, Cox NR, Baker HJ, Martin DR. (2009) Neurodegenerative lysosomal storage disease in European Burmese cats with hexosaminadase β-subunit deficiency. Molecular Genetics and Metabolism doi:10.1016/j.ymgme.2009.01.003

Veterinary Genetics Laboratory, Tel 530-752-2211, Email VGL