Categories: Behaviour / neurological phene , Renal / urinary system phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 618409 (gene)

Single-gene trait/disorder: yes

Mode of inheritance: Autosomal recessive

Disease-related: yes

Key variant known: yes

Year key variant first reported: 2025

Species-specific symbol: RBD

Molecular basis: Stee et al. (2025): "A disease-associated 23-bp deletion in exon 1 of FAM8A1 (NC_058372.1:g.11622168_11622190del), introducing a frameshift at codon 162 and a premature stop codon at codon 276 (XM_019831563.3:c.485_507del p.(Gln162Profs*115)), was identified by whole genome sequencing. The variant segregated in the affected families with a recessive mode of inheritance, showed an allele frequency of 1.5% in West-European Russian Blue cats (N = 68) and was not present in 276 cats belonging to 32 other breeds (including the closely related Nebelung breed)."

Clinical features: Stee et al. (2025): "Five young adult Russian Blue cats from two related families were presented for progressively worsening RBD episodes frequently associated with urinary loss. Three of these cats also suffered urinary retention with overflow incontinence between RBD episodes, [and one of these cats also had complains of fecal retention]. Neurological examination revealed a large bladder in three cats and a bilateral mydriasis with absent pupillary light reflexes in two cats; further examinations were unremarkable. Treatment attempts were unsatisfactory, with four cats being euthanized."

Pathology: Stee et al. (2025): "Histopathology of the brain did not reveal any abnormalities."

Breed: Russian Blue (Cat) (VBO_0100200).
Breeds in which the phene or likely causal variants have been documented. If a likely causal variant has been documented, see variant-specific breed information in the variant table. (Breed information may be incomplete).

Associated gene: