Test Detail

DNA panel for the Siamese and the Oriental Shorthair that combines genetic blood group determination with screening for four hereditary diseases: GM1 gangliosidosis, mucopolysaccharidosis type VI (MPS6), primary congenital glaucoma (PCG) and progressive retinal atrophy type rdAc. It covers the nervous, skeletal-metabolic and ocular systems. It is performed from a buccal swab or blood and identifies carrier and affected animals. It is especially relevant in Oriental breeds with a historically limited genetic base.

GM1 and MPS6 are rare diseases in current breeding. PCG appears sporadically in Siamese families. rdAc-PRA was initially characterized in the Abyssinian and the Somali, with moderate frequencies in those breeds, and has been detected in Siamese and Oriental lines; data in the breed are limited.

- GM1: neurodegeneration with progressive ataxia, tremor and paresis, with visceromegaly and corneal opacity
- MPS6: growth retardation, facial dysmorphism, joint stiffness, corneal opacity and skeletal deformities
- PCG: buphthalmos, elevated intraocular pressure, epiphora, corneal edema and blindness in young kittens
- rdAc-PRA: vision loss beginning in the young adult, with night blindness and tapetal hyperreflectivity
- Neonatal isoerythrolysis due to blood group incompatibility

GM1 gangliosidosis (beta-galactosidase deficiency) was described in the Siamese in the last decades of the 20th century as a model of the homologous human disease; the identification of the GLB1 gene variant enabled carrier testing. Mucopolysaccharidosis VI (arylsulfatase B deficiency) was also characterized in the breed, with severe and attenuated forms. Primary congenital glaucoma is recognized in the Siamese as a hereditary juvenile ophthalmopathy with autosomal recessive inheritance and complete penetrance; Kuehn et al. (2016) identified a 4-bp insertion in exon 8 of the LTBP2 gene as the cause of the disease. The rdAc-PRA form, caused by a variant of the CEP290 gene, was identified in the Abyssinian in 2007 and has since been detected in numerous breeds, including the Siamese and the Oriental.

- Never mate two carriers of GM1, MPS6 or rdAc-PRA: as expected 25% of the litter would be affected
- Carriers can be mated to clear animals and gradually withdrawn to preserve the genetic base of the breed
- In lines with a history of congenital glaucoma, be cautious given the lack of a confirmed DNA test: consult the laboratory
- Determine the blood group before mating to prevent neonatal isoerythrolysis

In GM1 and MPS6, determination of enzyme activity in leukocytes and, in MPS6, analysis of urinary glycosaminoglycans support the diagnosis. PCG requires early tonometry and ophthalmological assessment, with differential diagnosis against other congenital ocular malformations. rdAc-PRA is confirmed with fundus examination and electroretinogram; its onset in the young adult differentiates it from congenital retinopathies.

1. Menotti-Raymond M et al. 2007, mutación de CEP290 y atrofia progresiva de retina (rdAc) del gato. J Hered. PMID: 17507457
2. Bighignoli B et al. 2007, mutaciones de CMAH asociadas al grupo AB felino. BMC Genet. PMID: 17553163
3. Kuehn MH et al. 2016, mutación de LTBP2 causante de glaucoma congénito en gatos domésticos. PLoS One. PMID: 27149523
4. Uddin MM et al. 2013, gangliosidosis GM1 por la mutación c.1448G>C de GLB1. J Vet Med Sci. PMID: 23123943
5. Lyons LA et al. 2016, mucopolisacaridosis VI en gatos: aclaración sobre el diagnóstico genético. BMC Vet Res. PMID: 27370326
6. Lyons LA 2015, DNA mutations of the cat (revisión). PMID: 25701860