Related diseases

The MPS Society supports 25 MPS and related diseases including the Mucolipidoses, other ‘storage diseases’ and the following conditions which are similar to Mucopolysaccharide Diseases.

Symptoms can vary greatly but all forms are characterised by a degree of neurodegeneration and cognitive impairment.

Types of diseases

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What is Aspartylglycosaminuria?

Aspartylglycosaminuria (AGU) was first described by Dr Pollitt et al in 1968 and is a rare lysosomal storage disorder of the oligosaccharide family, closely related to the mucopolysaccharidoses.
Whilst there is no cure for individuals affected by this disorder this factsheet explores the presentation and clinical management of AGU. Bone Marrow Transplant and Enzyme Replacement Therapy are also addressed. This guide is produced by the Society for Mucopolysaccharide Diseases (MPS Society) drawing on the experiences of parents and doctors with reference to medical literature.

What causes AGU?
Oligosaccharides are long chains of sugar molecules used in the building of bones, cartilage, skin, tendons and many other tissues in the body. “Oligo” means a small number, “saccharide” is a general term for a sugar molecule. In the course of normal life there is a continuous process of building new oligosaccharides and breaking down old ones. This process requires a series of special biochemical tools called enzymes.
AGU is an enzyme deficiency disorder resulting in defective aspartylglycosaminidase enzyme activity which is essential for the chemical decomposition of oligosaccharides. Without the aspartylglycosaminidase enzyme used materials cannot be completely broken down and remain stored in the body causing progressive damage to cells. Babies may show little sign of the disease but symptoms start to appear as more and more cells become damaged by the accumulation of oligosaccharides.

Does AGU affect individuals differently?
Despite the rarity of diagnosed cases of AGU, follow-ups and studies carried out have shown consistency in the clinical picture. There do appear to be some differences in the severity of the disease between patients who carry the most common Finnish mutations of AGU and individuals from other countries who often have other, less well-known mutations. In these individuals the outcome can be much more severe, leading to a shorter life span than described in literature.

How common is AGU?
Approximately 250 cases are reported worldwide. Around 200 patients are living in or originate from Finland. It was initially thought that the disorder was exclusively particular to the Finnish population but a few sufferers from different origins have since been diagnosed with AGU.click the link to view our information sheet

What is Fucosidosis?

Fucosidosis is a rare lysosomal storage disorder of the Oligosaccharide family of diseases and is closely related to Mucopolysaccharidoses.
Fucosidosis was first described by Dr Durand in 1966 and the enzyme responsible for the condition was first identified by Van Hoof and Hers in 1968.
Fucosidosis is an enzyme deficiency disorder which results in defective fucosidase activity, the accumulation of lipids (fucose-rich oligosaccharides, sphingolipids and glycopeptides chains) and the absence of glycosaminoglycans (GAGs). This accumulation is responsible for many problems.

What Causes Fucosidosis?
Oligosaccharides are long chains of sugar molecules used in the building of bones, cartilage, skin, tendons and many other tissues in the body. “Oligo” means a small number and “saccharide” is a general term for a sugar molecule.
In the course of normal life there is a continuous recycling process of building new Oligosaccharides and breaking down old ones. This process requires a series of special biochemical tools called enzymes.
Children and adults affected with Fucosidosis have a missing or malfunctioning enzyme. This is called alphaL-fucosidase. Partially broken down fucose-containing chemicals remain stored in the body, build up and cause progressive damage to the cells.
Babies may show little sign of the disease but as more and more cells become damaged by accumulation of Oligosaccharides, symptoms start to appear.

How Common is Fucosidosis?
There are fewer than 100 cases that have been reported worldwide. It has been shown that approximately a third of those patients are of Italian origin.

Does Fucosidosis Affect Individuals Differently?
Fucosidosis, like most MPS and related disorders, is very variable and in the past has been divided up into two types, one of which presents itself in infancy. This is referred to as Type I. When an individual has a later onset of the disease this is known as Type II or ‘Juvenile’. This is an oversimplification, however as it is now recognised that these are two ends of the same disease spectrum.
It is important to remember that Fucosidosis is extremely varied in its effects. A whole range of possible symptoms are outlined in this fact sheet, however affected individuals may not experience all of them.

Geleophysic Dysplasia is a very rare disease which comes under a group of conditions related to the Mucopolysaccharidoses. It is a genetic degenerative storage condition leading to premature death often in childhood.

Geleophysic Dysplasia is characterised by extremely short stature, small hands and feet, failure to thrive and accompanying physical disabilities including progressive heart disease. Growth is severely limited with shortened limbs and joint mobility is generally decreased, especially in the hands.

GM1 Gangliosidosis is an inherited disorder that progressively destroys nerve cells (neurons) in the brain and spinal cord.

The condition has traditionally been classified into three major types based on the age at which signs and symptoms first appear.

  • Type I – Infantile
  • Type II – Late infantile and Juvenile
  • Type III – Adult/chronic

Although the three types differ in severity, their features can overlap significantly. Because of this overlap, researchers believe that GM1 Gangliosidosis represents a continuous disease spectrum instead of three distinct types.

All individuals with GM 1 Gangliosidosis have a deficiency, or absence, of the enzyme β-galactosidase which results in the accumulation of molecules that this enzyme is responsible for breaking down.

To date there are no specific treatments for GM 1 Gangliosidosis. Affected individuals receive a range of treatments to address the varying symptoms of the condition.

This condition is inherited in an autosomal recessive pattern, which means that in an affected individual, both copies of the associated gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they do not show signs and symptoms of the condition.

LAL D is a rare genetic condition, in which sufferers are deficient in lysosomal acid lipase. This lipase plays a key role in the regulation of cholesterol and triglyceride metabolism throughout the body. Without enough LAL to process these products, they accumulate in tissue affecting mainly the liver, spleen, adrenal glands, lymph nodes and small intestine.


LAL D is a rare disease, with estimates of its occurence in children and adults ranging from 1:40,000 and 1:300,000


Children and adults commonly show various liver dysfunctions and an abnormal amount of lipids in bloods. Individuals may also present gastrointestinal symptoms and cardiovascular problems, such as coronary artery disease.

Infants will show symptoms of the disease within the first few days to the first month of life, the first of these symptoms typically including vomiting and diarrhea and growth failure.


LAL D can be diagnosed with a simple blood test.

What is Alpha Mannosidosis?

Alpha Mannosidosis is a rare lysosomal storage disorder of the Glycoprotein family of diseases and is closely related to Mucopolysaccharidoses.
Alpha Mannosidosis was first described by Dr Oekerman, from Lund in Sweden in 1967. There is another variant known as ‘Beta Mannosidosis’ which is extremely rare and has produced a wide range of clinical abnormalities in the few patients described with this disorder.
Alpha Mannosidosis is an enzyme deficiency disorder which results in defective mannosidase activity (the accumulation of mannose-rich oligosaccharide chains). This accumulation is responsible for many problems that affect individuals with Alpha Mannosidosis.

What Causes Mannosidosis?
Oligosaccharides are long chains of sugar molecules used in the building of bones, cartilage, skin, tendons and many other tissues in the body. “Oligo” means a small number and “saccharide” is a general term for a sugar molecule.
In the course of normal life there is a continuous recycling process of building new Oligosaccharides and breaking down old ones. This process requires a series of special biochemical tools called enzymes. Children and adults affected with Alpha Mannosidosis have a malfunctioning or missing enzyme called Alpha Mannosidase.
Partially broken down Mannose-containing chemicals remain stored in the body and over time begin to build up. This causes progressive damage to the cells. Babies may show little sign of the disease but as more and more cells become damaged by accumulation of oligosaccharides, symptoms start to appear.

How Common is Alpha Mannosidosis?
It occurs in approximately 1 in 500,000 live births.
Source: www.orpha.net

Does Alpha Mannosidosis Affect Individuals Differently?
Alpha Mannosidosis, like most MPS and related disorders is very variable. Some individuals with Alpha Mannosidosis will have mild to moderate learning difficulties which may develop in childhood or adolescence.
It is important to remember that Alpha Mannosidosis is extremely varied in its effects. A whole range of possible symptoms are outlined in this fact sheet, however affected individuals may not experience all of them.click the link to view our information sheet

What is MLD?
MLD or Metachromatic Leukodystrophy is one of a group of rare genetically inherited diseases known as the lysosomal storage diseases. The condition gets its name from the microscopic appearance of cells with the sulfatide accumulation that occurs in this disorder. The sulfatides form granules which are metachromatic, which means they pick up colour differently than surrounding cellular material when stained for microscopic examination.

What causes MLD?
In the course of normal life there is a continuous recycling process; this process requires a series of biochemical tools called enzymes. Individuals with MLD lack a specific enzyme or protein in every one of their cells. This leads to problems with the breakdown of fats called sulfatides (or sulphatides).
In nearly all cases, MLD develops as a result of a deficiency in the enzyme arylsulfatase A (ASA) also known as sulfatidase or cerebroside 3-sulfatase. ASA is responsible for breaking down sulfatide and other fats that contain 3-sulfogalactosyl. The protein produced by ASA is present in the lysosome, a compartment of the cell that specialises in general “cleanup” of the cell.
You may hear MLD referred to as a lysosomal storage disorder, since ASA is a lysosomal enzyme. In rare cases, a deficiency of the non-enzymatic activator protein saposin B, which helps arylsulfatase A with the breakdown of these fats, can also cause metachromatic leukodystrophy. When arylsufatase A and saposin B are unable to work together to break down sulfatides, they build up in cells within the nervous system, including the brain.

Does MLD Affect Individuals Differently?
The severity of metachromatic leukodystrophy varies widely between patients. Although a gross oversimplification, affected individuals are generally described as having one of three main forms of the condition. These forms are identified based on the age of the patient when their first signs and symptoms start to appear. They are known as the late infantile, juvenile and adult forms.
If the disease first develops between 6 months and 4 years of age, the individual is said to have the late-infantile form of metachromatic leukodystrophy. The condition is described as juvenile if it develops between 4 and 16 years of age. Individuals who are older than 16 years when they develop metachromatic leukodystrophy are described as having the adult form of the disease. More recently, it has been suggested that the description of the late-infantile form should be revised to include only children who present before 2-3 years of age.

How common is MLD?
Metachromatic leukodystrophy is the commonest of all the leukodystrophies. However, it is still a rare disease that affects between about 1 in 54,000 and 1 in 166,650 live births. The adult-onset form of metachromatic leukodystrophy affects 25% of all patients. The remaining patients can be divided roughly equally between the lateinfantile and juvenile forms.

Mucolipidosis type I (ML I), also known as Sialidosis, is a rare inherited lysosomal storage disease that has clinical and histologic findings similar to the mucopolysaccharidoses and the sphingolipidoses. Symptoms of ML I are either present at birth or develop within the first year of life. In many infants with ML I, excessive swelling throughout the body is noted at birth. These infants are often born with coarse facial features, such as a flat nasal bridge, puffy eyelids, enlargement of the gums, and excessive tongue size (macroglossia).

Many infants with ML I are also born with skeletal malformations such as hip dislocation. Infants often develop sudden involuntary muscle contractions (called myoclonus) and have red spots in their eyes (called cherry-red macules). They are often unable to coordinate voluntary movement (called ataxia). Tremors, impaired vision, and seizures also occur in children with ML I.

Tests reveal abnormal enlargement of the liver and spleen and extreme abdominal swelling. Infants with ML I generally lack muscle tone (hypotonia) and have impaired intellect that is either initially or progressively severe. Many patients suffer from failure to thrive and from recurrent respiratory infections.

What is ML II?
Mucolipidosis Type II (ML II) is one of the lysosomal storage disorders known collectively as Mucolipidoses. These disorders are closely related to Mucopolysaccharidosis. ML II is sometimes referred to as ‘I-Cell Disease’. This term is derived from the observation of changes within a cell known as the fibroblast. A healthy fibroblast cell has a specific shape but in individuals affected by ML II this shape changes as a result of the accumulation of storage materials. Dr. Jules Leroy from Belgium was one of the first doctors to write about the condition in the 1960’s and his name is sometimes used to refer to ML II.

What Causes ML II?
In the course of normal life there is a continuous recycling process of building new materials and breaking down old ones ready for disposal. This activity takes place in a special part of the body’s cells called the lysosome. The process requires a series of biochemical tools called enzymes. Enzymes can only reach the lysosomes after a special signal has been attached to them. In children with ML II the signal is not attached so the enzymes are unable to get to the right place and are therefore lost outside the cell. Babies may show little sign of the disease but symptoms start to appear as more and more cells become damaged by the accumulation of unwanted deposits.

How Common is ML II?
The worldwide prevalence is unknown. Estimated live birth prevalence values have been reported in Portugal (1/123,500), Japan (1/252,500), the Netherlands (1/625,500) and Ireland (1/64,100). A founder effect has been reported the in Saguenay-Lac-St-Jean region of Quebec.

Does ML II Affect Individuals Differently?
This disease encompasses a spectrum of clinical symptoms which, at the severe end of the spectrum are labelled ML II. Less severely affected individuals are considered to have ML III.

What is ML III?
Mucolipidosis Type III (ML III) is one of the lysosomal storage disorders known collectively as Mucolipidoses and is closely related to Mucopolysaccharidoses. ML III is sometimes referred to as Pseudo-Hurler Polydystrophy as it resembled a less severe form of Hurler Disease (MPS I). Polydystrophy means that many organs are abnormal. ML III was first described in 1966 by Dr Maroteaux and Dr Lamy from France.

What Causes ML III?
In the course of normal life there is a continuous recycling process of building new materials and breaking down old ones ready for disposal. This activity takes place in a special part of the body’s cells called the lysosome. This process requires a series of biochemical tools called enzymes which can only reach the lysosomes after a special signal has been attached to them. In individuals with ML III this signal is not attached so the enzymes are unable to get to the right place and are therefore lost outside the cell. Babies may show little sign of the disease but symptoms start to appear as more and more cells become damaged by the accumulation of unwanted deposits.

Does ML III Affect Individuals Differently?
Mucolipidoses are a group of storage disorders displaying a spectrum of clinical symptoms. At the severe end, these are labeled ML II. Less severely affected individuals are considered to have ML III.

What is Mucolipidosis IV?
Mucolipidosis IV (ML IV) is a rare genetic disorder belonging to a group of disorders known as the lysosomal disorders. It is most commonly seen in Jews of Eastern European background. Other names for this condition include Ganglioside Sialidase Deficiency and Sialolipidosis.

What causes ML IV?
ML IV is a rare inherited metabolic disorder believed to be caused by alterations in a membrane protein due to mutations in the mucolipin-1 gene. This results in the blockage of endocytic transport which is the absorption of materials, for example, into the cell. This prevents the lysosomes forming correctly which results in a storage of complex lipids within the lysosome. This can cause iron deficiency anaemia and the neurodegenerative features seen in ML IV.

How common is ML IV?
The disease is rare in the general population but is more prevalent among Ashkenazi Jews, among whom the prevalence at birth is 1 in 40 000 corresponding to a frequency of heterozygotes of 1 in 100.
Source: www.orpha.net

Free sialic acid storage disorders are a group of related disorders characterised by the abnormal accumulation of sialic acid in various cells and tissues of the body. They are inherited through autosomal recessive inheritance.

There are three subtypes:

  • Infantile free sialic acid storage disease (ISSD) which is the most severe;
  • Intermediate Salla disease
  • Salla disease, the mildest form

Symptoms can vary greatly but all forms are characterised by a degree of neurodegeneration and cognitive impairment.

What is Winchester Syndrome?
Winchester Syndrome, also known as Multicentric osteolysis-nodulosis-arthropathy (MONA), is an inherited bone disorder. Although it is not one of the mucopolysaccharidosis it has many features in common with MPS disorders.
A rare systemic or rheumatologic disease characterized by peripheral osteolysis (especially carpal and tarsal bones), interphalangeal joint erosions, subcutaneous fibrocollagenous nodules, facial dysmorphism, and a wide range of associated manifestations.

How common is Winchester Syndrome?
Multicentric osteolysis-nodulosis-arthropathy (MONA) spectrum prevalence and incidence of MONA are not known. Fewer than 50 cases have been reported worldwide. Cases have been reported from Saudi Arabia, Italy, Turkey, Algeria, Morocco, the United States, and Korea.

What causes Winchester Syndrome?
Winchester Syndrome is caused by an alteration in a gene called MMP2. It is also known as Torg Syndrome and Multicentric Osteolysis with Nodulosis and Arthropathy (MONA) are caused by alterations in the same gene.