Pseudo-Hurler polydystrophy, also referred to as mucolipidosis

Mucolipidosis

Mucolipidosis is a group of inherited metabolic disorders that affect the body's ability to carry out the normal turnover of various materials within cells....

 III (ML III), is a lysosomal storage disease

Lysosomal storage disease

Lysosomal storage diseases are a group of approximately 50 rare inherited metabolic disorders that result from defects in lysosomal function...

 closely related to I-cell disease

I-cell disease

Inclusion-cell disease, also referred to as mucolipidosis II , is part of the lysosomal storage disease family and results from a defective phosphotransferase . This enzyme transfers phosphate to mannose residues on specific proteins, and serves as a marker for them to be targeted to lysosomes...

 (ML II). This disorder is called Pseudo-Hurler because it resembles a mild form of Hurler syndrome

Hurler syndrome

Hurler syndrome, also known as mucopolysaccharidosis type I , Hurler's disease, also gargoylism, is a genetic disorder that results in the buildup of glycosaminoglycans due to a deficiency of alpha-L iduronidase, an enzyme responsible for the degradation of mucopolysaccharides in lysosomes...

, one of the mucopolysaccharide (MPS) diseases.

Pathophysiology

As in Mucolipidosis II, Mucolipidosis III results from genetic defects in GlcNAc phosphotransferase (N-acetylglucosamine-1-phosphotransferase). However, ML III produces less severe symptoms and progresses more slowly, probably because the defect in GlcNAc phosphotranspherase lies in its protein recognition domain. Therefore, the catalytic domain retains some of its activity, resulting in a smaller accumulation of carbohydrates, lipids, and proteins in the inclusion bodies.

Presentation

Symptoms of ML III are often not noticed until the child is 3–5 years of age. Patients with ML III are generally of normal intelligence

Intelligence

Intelligence has been defined in different ways, including the abilities for abstract thought, understanding, communication, reasoning, learning, planning, emotional intelligence and problem solving....

 (trait) or have only mild mental retardation

Mental retardation

Mental retardation is a generalized disorder appearing before adulthood, characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behaviors...

. These patients usually have skeletal abnormalities, coarse facial features, short height, corneal clouding, carpal tunnel syndrome

Carpal tunnel syndrome

Carpal Tunnel Syndrome is an entrapment idiopathic median neuropathy, causing paresthesia, pain, and other symptoms in the distribution of the median nerve due to its compression at the wrist in the carpal tunnel. The pathophysiology is not completely understood but can be considered compression...

, aortic valve

Aortic valve

The aortic valve is one of the valves of the heart. It is normally tricuspid , although in 1% of the population it is found to be congenitally bicuspid . It lies between the left ventricle and the aorta....

 disease and mild enlargement of organs. Some children with severe forms of this disease do not live beyond childhood. However, there is a great variability among patients, and individuals with ML III can survive until their fourth or fifth decade of life.

Treatment

There is no cure for Pseudo-Hurler Polydystrophy/Mucolipidosis IIIA. Treatment is limited to controlling or reducing symptoms associated with this disorder. Physio-therapy, particularly hydrotherapy

Hydrotherapy

Hydrotherapy, formerly called hydropathy, involves the use of water for pain-relief and treating illness. The term hydrotherapy itself is synonymous with the term water cure as it was originally marketed by practitioners and promoters in the 19th century...

 has proven effective at relieving muscle stiffness and increasing mobility. The use of crutches, a wheelchair or scooters are treatment options as the metabolic bone disease progresses. The insertion of rods in the spine to stabilize the vulnerable areas can treat scoliosis

Scoliosis

Scoliosis is a medical condition in which a person's spine is curved from side to side. Although it is a complex three-dimensional deformity, on an X-ray, viewed from the rear, the spine of an individual with scoliosis may look more like an "S" or a "C" than a straight line...

. Heart valve replacement surgery may be necessary as this disorder progresses.

External links

• Hide and Seek Foundation For Lysosomal Disease Research - original text of article derived from detail sheet available here