Comparison of the mucolipidosis (ML) II and ML III phenotypes
| Finding | ML II | ML III |
| Intrauterine growth | Low to normal | Normal |
| Growth, stature | Stops before age 2 years | Slow growth after age 4 years |
| Final stature* | <80 cm | >115 cm |
| Onset of signs | Birth to early infancy | Early to mid-childhood |
| Craniofacial features | From birth, pronounced gingival hypertrophy and coarse features, including round cheeks, shallow orbits, depressed nasal bridge | Gradual coarsening of facial features beginning 5–8 years of age; mild gingival hypertrophy with normal tooth eruption |
| Hands, fingers | Short, broad, early clawing | Normal to long, late distal clawing |
| Unaided walking | Rarely achieved | Achieved with mild to no delay; independent ambulation variably declines as disease progresses |
| Speech | Delayed, limited expressive language | Normal |
| Cognitive function | Mild to moderate deficit, rarely severe | Borderline to normal |
| Hands radiographs | Short tubular bones, progressing to severe diaphyseal widening | Minimally short tubular bones, diaphyseal narrowing partially preserved |
| Vertebral radiographs | AP shortening, biconcave outline, irregular borders | AP elongation, mild platyspondyly, irregular borders |
| Activity of GlcNAc-1-phospho-transferase (leucocyte or fibroblasts) | <1% of control value | 1–10% of control value |
↵* Statural measurement difficult in later part of clinical course in either clinical entity because of joint restriction.
AP, anteroposterior.