Mannoside storage disease type II most often develops after the age of 2 years, with normal physical and psychomotor development, progressive cerebral retardation starting after the age of 2 years, frequent respiratory infections, ugly face, thick eyebrows, widened spacing between incisors, convex jaws, low anterior hairline, and mild bilateral deafness (mostly sensory). Some patients may have allodynia. Widened spacing of incisors is one of the symptoms of mannoside storage disease type II. It needs to be differentiated from: Mannoside Storage Disease: It is a systemic disease caused by alpha-mannosidase deficiency. The clinical features are similar to Hurler’s syndrome, without mucopolysacchariduria, but with an increased mannose-containing component in the tissues. Mucolipidosis type 1: Mucolipidosis type I (ML I) is an autosomal recessive disorder caused by a deficiency of lysosomal α-neuraminidase, which leads to a large amount of salivary acid storage, and is also known as salivary acid enzyme deficiency. Mucolipid storage disease type II: Mucolipid storage disease type II is also known as inclusion celldisease, or I-cell disease for short. Its clinical features are more like Hurler’s syndrome, manifested by obvious clinical and X-ray abnormalities at birth, unresponsive, but without mucopolysacchariduria, skin fibroblast culture has a large number of coarse cytoplasmic inclusion bodies, Leroy et al. (1967) first discovered this disease, Spranger (1970) classified it as mucolipid storage disease type II. Mucolipid storage disease type III: this disease is autosomal recessive inheritance, Strecker et al. (1976) found that the patients with this disease tissue cell neuraminidase deficiency, may be the lack of this kind of enzyme and a variety of lysosomal hydrolases recognition site abnormality is related to, such as hexokinase, β-glucosidase, β-galactosidase and so on the recognition site of the defects, resulting in excessive neutral, acidic mucopolysaccharides and mucolipids deposition in the tissue cells and caused the disease. This causes excessive deposition of neutral and acidic mucopolysaccharides and mucolipids in the tissue cells and leads to disease.