Mutations that alter only the C-terminal of the protein also result in a mild phenotype of the disorder, usually sparing the brain. ML IV causes affected cells to accumulate auto-fluorescent vacuoles considered to be aberrant lysosomes. Several evidences exist for a defect in both exocytosis and endocytosis. There are conflicting indications of abnormal lysosomal pH in MLIV. It is not yet clear why these abnormalities will cause incomplete development of the brain, achlorhydria, and failure in the maintenance of retinal tissue. Diagnosis
Diagnosis includes genetic testing and Gastrin blood test to check for low iron in the blood. Treatment
There is no specific treatment to this disorder. However, several symptoms may be alleviated. For instance, anemia is treated by iron supplements. Some of the movement deficiencies may be corrected with orthopedic intervention. The corneal clouding can be, at least, temporarily corrected by corneal transplantation. See the equivalent section in the main mucolipidosis article. Epidemiology
Mucolipidosis type IV is severely under-diagnosed. It is often misdiagnosed as cerebral palsy. In the  Ashkenazi Jewish population there are two severe mutations with a higher carrier frequency of 1:90 to 1:100. References
External links

Mucolipidosis type 4 at NIHs Office of Rare Diseases
Parietal lobe: Tumors here may result in poor interpretation of languages, difficulty with speaking, writing, drawing, naming, and recognizing, and poor spatial and visual perception. Occipital lobe: Damage to this lobe may result in poor vision or loss of vision. Cerebellum: Tumors in this area may cause poor balance, muscle movement, and posture. Brain stem: Tumors on the brainstem can cause seizures, endocrine problems, respiratory changes, visual changes, headaches and partial paralysis. Behavior changes
A persons personality may be altered due to the tumor damaging lobes of the brain. Since the frontal, temporal, and parietal lobes control inhibition, emotions, mood, judgement, reasoning, and behavior, a tumor in those regions can cause inappropriate social behavior, temper tantrums, laughing at things which merit no laughter, and even psychological symptoms such as depression and anxiety. More research is needed into the effectiveness and safety of medication for depression in people with brain tumors.Personality changes can have damaging effects such as unemployment, unstable relationships, and a lack of control. Cause
Epidemiological studies are required to determine risk factors. Aside from exposure to vinyl chloride or ionizing radiation, there are no known environmental factors associated with brain tumors. Mutations and deletions of tumor suppressor genes, such as P53, are thought to be the cause of some forms of brain tumor. Inherited conditions, such as Von Hippel–Lindau disease, tuberous sclerosis, multiple endocrine neoplasia, and neurofibromatosis type 2 carry a high risk for the development of brain tumors. People with celiac disease have a slightly increased risk of developing brain tumors.