This is an inherited disease that presents problems with the normal turnover of certain substances within the cells and as the result, the abnormal accumulation of carbohydrates and lipids occur. As the result of this accumulation, damage to cells can occur that can develop various associated symptoms such as mild learning difficulties to severe intellectual problems and deformities. This condition can be evident at the birth of the infant or in early childhood presenting poor mental capabilities over time and death can occur in many of the cases. There is no cure for the disease but the treatment aims in providing support and relief from the symptoms. There are four types of mucolipidoses; type I, type II, type III and IV.
Type I
This occurs as the result of a deficiency in the digestive enzyme known as sialidase which functions to remove a particle from the sugar-protein complexes that ensures the normal function of the cell. As the result of this deficiency, the sugar-like material can accumulate in various parts of the body such as the neurons, bone marrow and various cells. The symptoms of type I include the swelling throughout the body and present coarse facial features such as puffy eyelids, flat nasal bridge and an enlarged tongue. They affected infants can also present skeletal malformations, sudden involuntary muscle contractions, inability to coordinate voluntary movement, impaired vision, impaired intellect, abnormal enlargement of the liver and the spleen. Most of the affected infants tend to die before they reach age one.
Types II and III
This develops as the result of a deficiency in the enzyme called N-acetylglucosamine-1 phototransferase. This enzyme acts as activator proteins that can initiate various metabolic activities in the cell. This enzyme deficiency results in the proteins not breaking down various substances inside the cell. Type II is considered to be a severe form of this condition presenting symptoms such as abnormal skeletal development, coarse facial features, enlargement of organs, lack of growth and restricted joint movements. They also tend to develop various recurrent respiratory tract infections including pneumonia. The affected children tend to die before their seventh year of life as the result of the heart failure or the respiratory tract infections.
Type III is considered to be a milder form of this condition presenting deficiency in enzymes that retain some of their functional activity. The condition may not be evident until the child reaches 3-5 years of age with the symptoms developing progressively. The affected child may present normal intelligence but have skeletal abnormalities, coarse facial features and the short stature. Some of the cases of this type appear to survive until their fourth or fifth decade of life.
Type IV
This develops because of the problems of a protein that is responsible for the transportation of materials such as calcium across cell membranes. These affected cases present symptoms such as delayed movement development and coordination, reduced vision of the eye, unsteady gait and impaired speech. They can also have lower production of acid by the stomach which can cause an increase in the gastrin hormone in the blood.
References
https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Mucolipidoses-Fact-Sheet
http://www.medindia.net/patients/patientinfo/mucolipidoses.htm
https://www.ucl.ac.uk/ion/library/patient-info/a-z/m-o/mucolipidoses
