Multi-disease genetic panel for the Leonberger grouping four molecular tests for hereditary polyneuropathies: laryngeal paralysis with polyneuropathy type 3 (LPPN3), leukoencephalomyelopathy (LEMP), polyneuropathy type 2 (LPN2) and polyneuropathy type 1 (LPN1). Each condition has its own molecular basis and inheritance. The panel is complementary to the neurological and electrodiagnostic examination in breeding selection.

Leonberger. LPN1 and LPN2 have been extensively screened in the breed; frequencies have decreased in controlled populations. LPPN3 and LEMP have a smaller caseload. Reliable carrier frequencies are not published systematically for all of them (limited data).

- LPPN3: laryngeal paralysis (stridor, voice change) with signs of polyneuropathy\n- LEMP: severe ascending paraparesis with juvenile onset\n- LPN2: progressive muscle weakness, exercise intolerance, ataxia\n- LPN1: weakness, muscle atrophy, exercise intolerance, juvenile onset

Each Leonberger polyneuropathy was characterised independently. LPN1 was associated with ARHGEF10, LPN2 with GJA9, LPPN3 with NAPEPLD and LEMP with NAPEPLD at a distinct locus. All are inherited in an autosomal recessive manner except LPN2 (dominant with incomplete penetrance).

- Genotype breeding animals before mating (four tests in a single sample)\n- For LPPN3, LEMP and LPN1 (recessive): do not mate two carriers — 25% affected homozygotes; carrier×clear is safe if tested\n- For LPN2 (incomplete dominant): heterozygotes may develop the disease; prioritise clear animals\n- In the presence of signs of laryngeal paralysis or progressive weakness, include the four conditions in the differential diagnosis\n- After a confirmed case, do not repeat the parental mating and communicate the status to the buyer

The diagnosis of each polyneuropathy combines electrodiagnostics (EMG, nerve conduction velocity), nerve biopsy and molecular testing. LEMP is diagnosed by MRI (spinal white matter lesions). Differentiate between the four polyneuropathies by age of onset, progression pattern and specific molecular test. No curative treatment in general; supportive management.

1. Letko A et al. 2016, LPPN3 por NAPEPLD en Leonberger
2. Lucot KL et al. 2018, LEMP por NAPEPLD en Leonberger
3. Plassais J et al. 2017, LPN2 por GJA9 en Leonberger
4. Bruun CS et al. 2018, LPN1 por ARHGEF10 en Leonberger
5. OMIA:002049 LPPN3; OMIA:001823 LEMP; OMIA:001545 LPN2; OMIA:001500 LPN1