Genetic panel for the Bolonka Zwetna combining two progressive retinal atrophy (PRA) tests — the cord1 form (RPGRIP1, cone-rod dystrophy) and the prcd form (PRCD, progressive rod-cone degeneration) — with two coat-trait tests: colour dilution (D-locus d1) and furnishing (moustache and eyebrows/long facial hair). The panel supports breeding selection for both ocular health and coat colour and type. The cord1 test is offered as a risk marker, without published breed-specific validation in the Bolonka.

Bolonka Zwetna. No verifiable population frequencies are available for any of the four variants in this breed (limited data). The RPGRIP1 (cord1) variant is a pan-breed marker present in multiple breeds, but the breed-specific clinical association is not published in the Bolonka; prcd-PRA is described in more than 20 breeds. Screening of breeding animals is recommended before breeding, especially for the ocular forms.

- cord1-PRA: progressive visual loss, often of variable onset, with fundus changes\n- prcd-PRA: night blindness and progressive visual loss with adult onset\n- D-locus d1: in homozygosity, diluted coat tone (blue/fawn); no clinical signs\n- Furnishing: longer facial and eyebrow hair (beard/moustache); no clinical signs

cord1-PRA was associated in the Miniature Long-haired Dachshund with a 44 bp insertion in exon 2 of RPGRIP1 (Mellersh et al., 2006) and is also described in the English Springer Spaniel. There is no known breed-specific validation of this variant in the Bolonka Zwetna: published data across 132 breeds indicate that the RPGRIP1 variant segregates in multiple breeds, but with established clinical relevance mainly in the Miniature Long-haired Dachshund (Donner and Mellersh, 2024). prcd-PRA is associated with the classic PRCD variant (c.5G>A, p.C2Y), the most prevalent form of PRA in dogs. D-locus d1 dilution corresponds to the classic MLPH variant. Furnishing is associated with a 167 bp insertion in the 3'UTR of RSPO2 (Cadieu et al., 2009), a trait with variable expression.

- Genotype breeding animals for RPGRIP1, PRCD, MLPH (d1) and RSPO2 before mating\n- For cord1 and prcd PRA: do not mate two carriers of the same variant\n- If an animal is a carrier of both cord1 and prcd, prioritize a mate clear for both variants\n- For cord1, interpret the result with caution: the variant is a risk marker without breed-specific validation in the Bolonka\n- For D-locus d1 and furnishing: the choice of matings is partly aesthetic; inform the buyer of the status\n- A carrier can be mated to a clear animal and offspring intended for breeding must be tested\n- After a confirmed case of PRA, do not repeat the parental mating and communicate the status to the buyer

cord1-PRA has variable penetrance: a dog homozygous for the RPGRIP1 variant may not develop clinical disease, which has generated debate about the usefulness of the test alone; moreover, breed-specific validation in the Bolonka is not established. prcd-PRA is the most prevalent form and should be screened in breeds with known carrier frequency. Dilution (d1) in homozygosity may be associated in some breeds with colour dilution alopecia; in the Bolonka it is not a systematic problem. Furnishing is a dominant trait desired in bearded breeds; the test helps predict the coat phenotype in the litter.

1. Mellersh CS, et al. Canine RPGRIP1 mutation establishes cone-rod dystrophy in miniature longhaired dachshunds as a homologue of human Leber congenital amaurosis. Genomics. 2006. PMID: 16806805.
2. Zangerl B, et al. Genomics. 2006. PMID: 16938425.
3. Drögemüller C, et al. A noncoding MLPH SNP at the splice donor of exon 1 represents a candidate causal mutation for coat color dilution in dogs. J Hered. 2007. PMID: 17519392.
4. Cadieu E, et al. Coat variation in the domestic dog is governed by variants in three genes. Science. 2009. PMID: 19713490.
5. Donner J, Mellersh C. Frequency of RPGRIP1 and MAP9 genetic modifiers of canine progressive retinal atrophy, in 132 breeds of dog. Anim Genet. 2024. PMID: 38752391.
OMIA:001432-9615 (cord1/RPGRIP1); OMIA:000031-9615 (D-locus/MLPH); OMIA:001531-9615 (furnishing/RSPO2).