An autosomal recessive, neurodevelopmental abnormality spontaneously arose in a domestic cat closed breeding colony at Auburn University that was established to study lysosomal storage diseases, and in which pathogenic variants are segregating for GM2 gangliosidosis variant AB (GM2A) [11], and mucopolysaccharidosis VI (MPSVI) [12]. Here, GM2A is linked to mucopolysaccharidosis type 6.