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Mucopolysaccharidoses
Mucopolysaccharidoses, commonly referred to as MPS, are a group of rare genetic metabolic disorders, and are regarded as lysosomal storage disorders.
Normally, the body makes enzymes to break down materials for our cells. For people with MPS and related diseases, the missing or insufficient enzyme prevents that normal process for the sugar glycosaminoglycans (or mucopolysaccharides), so they become stored in almost every cell of the body. As a result, cells do not function properly and cause progressive damage to the person throughout the body, including the heart, bones, joints, respiratory system, and nervous system. While the disease is not immediately apparent at birth, signs and symptoms develop with age as more cells become damaged by the accumulation of cell deposits. Most patients usually do not live through their twenties.
Mucopolysaccharidoses exist in a total of seven types ---- MPS I, II, III, IV, VI, VII, IX --- and numerous subtypes. There are no type V and VIII. The seven types are subdivided to subtypes according to enzyme defect and symptoms shown by the body. Although each type of MPS is clinically different, most patients generally experience a period of normal development and then followed by a decline in physical and/or mental function.
Types |
Disease Subtypes |
Cause |
Symptoms and Treatments |
How Common (Incidence estimates) |
No. of Patients in HK* |
| MPS I |
From most severe to the mildest: |
Lack of the enzyme alpha-L-iduronidase
Both parents also carry the defective gene. |
 PDF file |
|
2 |
| * Hurler syndrome (MPS I-H) |
MPS I-H: about 1 per 100,000 births. |
| * Hurler-Scheie syndrome (MPS I-HS) |
MPS I-HS: about 1 per 115,000 births. |
| * Scheie syndrome (MPS I-S) |
MPS I-S: about 1 per 500,000 births. |
MPS II
(Hunter syndrome) |
From most severe to the mildest: |
Lack of the enzyme iduronate sulfatase
The defective gene was passed from the mother. |
PDF file |
|
6 |
| * MPS II A |
MPS II A: Similar to Hurler syndrome but much milder |
1 per 100,000 to 150,000 male births. |
| * MPS II B |
MPS II B: Less obvious and slower progression |
Onset usually at 2-4 years old. |
MPS III
(Sanfilippo syndrome) |
|
Lack of the enzyme heparan sulphate
Both parents also carry the defective gene. |
PDF file |
About 1 per 24,000 to 70,000 births. |
6 |
MPS IV
(Morquio syndrome) |
|
Lack of the enzyme keratan sulphate
Both parents also carry the defective gene. |
PDF file |
About 1 per 200,000 births. |
7 |
MPS VI
(Maroteaux-Lamy syndrome) |
|
Lack of the enzyme dermantan
Both parents also carry the defective gene. |
PDF file |
About 1 per 215,000 births. |
4 |
MPS VII
(Sly syndrome) |
|
Lack of the enzyme beta-glucuronidase |
PDF file |
< 1 per 250,000 births |
0 |
MPS IX
(Natowicz syndrome) |
|
Lack of the enzyme hyaluronidase |
|
Only 1 reported case in the world |
0 |
Number of MPS patients =25 |
Other Rare Genetic Diseases
Types |
Cause |
Symptoms and Treatments |
How Common (Incidence Estimates) |
No. of Patients in HK* |
| Mucolipidosis |
Lack of enzymes to break down carbohydrates and lipids |
Early onset may include rigid arms and shoulders, later on with carpal tunnel syndrome. Half of the patients have hearing impairment and a mild form of mental impairment.
PDF file |
About 2-3 per 100,000 births. |
1 |
| Gaucher's disease |
Deficiency of enzyme glucocerebrosidase (also known as acid β-glucosidase) |
Hepatosplenomegaly, sports regulatory function of the imbalance, small limbs, bone deformation, fracture easily
Click for more details |
About 1 per 100,000 births. |
1 |
| Glutaric aciduria Type I |
Lack of an enzyme |
Neurological symptoms such as muscle stiffness, hand-foot-progressive chorea, paralysis, corner arch anti-sheets, legs turned out, the body was arcuate and so on, may have epilepsy, or sleeping with acute onset of coma
Click for more details |
|
1 |
| Glycogen storage disease |
Lack of enzymes to breakdown glycogen |
Drowsiness, trembling, slow growth, increased abdominal circumference, fat accumulation in the cheek into a rounded doll-like. Nosebleeds or ears to inflammation, gingivitis, sores symptoms. After the emergence of rickets, anemia symptoms. Gland tumor complications such as liver, progressive renal failure, kidney stones, gout, anemia, osteoporosis, etc.
|
About 1 per 10,000 births. |
1 |
Pompe disease
(Glycogen storage disease Type II) |
Lack of acid maltase |
Ventricular fat or less rapid expansion of the heart, eventually causing obstruction to aortic flow, muscle weakness.
Death by around 2 years old
Click for more details |
About 1 per 40,000 births. |
2 |
| Multiple sclerosis |
Virus or inflammation affecting the immune system |
Neurological symptoms such as visual disorders, tremor, numbness, dizziness, weakness, leg stiffness. These may go away or sustain, or worsen over time.
More common in women.
Click for more details |
About 2-5 per 100,000 births. |
1 |
| Phenylketouria (PKU) |
Lack of an enzyme to breakdown amino acids |
Infants abnormally drowsy, unusually light skin. Feeding difficulties. Severe mental retardation if no treatment
Click for more details |
Varies greatly in regions and ethnicity |
1 |
Sotos Syndrome
(Cerebral Gigantism) |
Mutation in a gene |
Excessive growth before and after birth, abnormally prominent forehead, and developmental delays in most children
Click for moe details |
About 1 per 14,000 births. |
2 |
| Hereditary epidermolysis bullosa |
Mutation in the keratin gene |
Recurring painful blisters and open sores, often after minor trauma, due to unusually fragile nature of the skin
Click for more details |
About 1 per 50,000 births. |
0 |
Urea cycle disorder |
Lack of an enzyme in the urea cycle to remove ammonia from the blood stream |
Amine caused by high blood coma, vomiting
Click fo more details |
About 1 per 10,000 births |
1 |
| Fabry disease |
Lack of the enzyme alpha-galactosidase A |
Pain or strange feeling, sometimes even burning feeling, at the hands and feet during childhood or adolescence.
Dark purple skin colour at the lower abdomen, thigh, prostate or external sexual organ.
Click fo more details |
|
0 |
Unknown
|
|
Developmental delays
|
|
1 |
Number of patients with other rare genetic diseases =12 |
Total Number of Patients with Rare Genetic Diseases =37 |
* Note: Patient figures according to the number of patients who contacted our organization.
For information about other organizations and treatments for rare genetic diseases, please click
here.
Updated: February 23, 2010 |
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