α-mannosidosis is a rare, autosomal, recessively inherited lysosomal storage disease caused by deficiency of the enzyme α-D-mannosidase.
This leads to accumulation of oligosaccharides (large sugar molecules) in a number of organs including the brain, kidney and liver.
Age of onset and progression of clinical signs can be variable, which may reflect some degree of heterogeneity (variability) in the degree of enzyme deficiency. Reported clinical signs include:
- Ataxia (uncoordinated walking)
- Intention tremors
- Neonatal deaths
- Bizarre behaviour/dementia
- Liver enlargement
- Corneal and lens opacification
- Growth retardation
- Premature death
Vacuoles may be detected in white cells (lymphocytes and monocytes) from blood samples, and mannose-rich oligosaccharides can be detected in urine samples (supporting the diagnosis).
The disease has been seen in domestic shorthair cats, domestic longhair cats and in Persian cats, and gene defects have been identified.