A large British study from 2008 found a median estimated life expectancy of 11.6 years.

Hurler syndrome has an overall frequency of one per 100,000. The mucopolysaccharidoses as a whole have a frequency of one in every 25,000 births.

Incidence of Sanfilippo syndrome varies geographically, with approximately 1 case per 280,000 live births in Northern Ireland, 1 per 66,000 in Australia, and 1 per 50,000 in the Netherlands.

The Australian study estimated the following incidences for each subtype of Sanfilippo syndrome:

MPS II, Hunter syndrome or iduronate sulfatase deficiency, is caused by lack of the enzyme iduronate sulfatase. Hunter syndrome has two clinical subtypes and (since it shows X-linked recessive inheritance) is the only one of the mucopolysaccharidoses in which the mother alone can pass the defective gene to a son. The incidence of Hunter syndrome is estimated to be 1 in 100,000 to 150,000 male births.

Sanfilippo syndrome, or mucopolysaccharidosis III (MPS-III) is a rare autosomal recessive lysosomal storage disease. It is caused by a deficiency in one of the enzymes needed to break down the glycosaminoglycan heparan sulfate (which is found in the extra-cellular matrix and on cell surface glycoproteins).

Although undegraded heparan sulfate is the primary stored substrate, glycolipids such as gangliosides are also stored despite no genetic defect in the enzymes associated with their breakdown.

The condition is named for Sylvester Sanfilippo, the pediatrician who first described the disease.

It is estimated that 1 in 25,000 babies born in the United States will have some form of the mucopolysaccharidoses. It is an autosomal recessive disorder, meaning that only individuals inheriting the defective gene from both parents are affected. (The exception is MPS II, or Hunter syndrome, in which the mother alone passes along the defective gene to a son.) When both people in a couple have the defective gene, each pregnancy carries with it a one in four chance that the child will be affected. The parents and siblings of an affected child may have no sign of the disorder. Unaffected siblings and select relatives of a child with one of the mucopolysaccharidoses may carry the recessive gene and could pass it to their own children.

Hunter syndrome, or mucopolysaccharidosis II (MPS II), is a lysosomal storage disease caused by a deficient (or absent) enzyme, iduronate-2-sulfatase (I2S). The accumulated substrates in Hunter syndrome are heparan sulfate and dermatan sulfate. The syndrome has X-linked recessive inheritance.

MLD has an autosomal recessive inheritance pattern. The inheritance probabilities "per birth" are as follows:

- If both parents are carriers:

- 25% (1 in 4) children will have the disease

- 50% (2 in 4) children will be carriers, but unaffected

- 25% (1 in 4) children will be free of MLD – unaffected child that is not a carrier

- If one parent is affected and one is free of MLD:

- 0% (0) children will have the disorder – only one parent is affected, other parent always gives normal gene

- 100% (4 in 4) children will be carriers (but unaffected)

- If one parent is a carrier and the other is free of MLD:

- 50% (2 in 4) children will be carriers (but unaffected)

- 50% (2 in 4) children will be free of MLD – unaffected child that is not a carrier

In addition to these frequencies there is a 'pseudo'-deficiency that affects 7–15% of the population. People with the pseudo deficiency do not have any MLD problems unless they also have affected status. With the current diagnostic tests, Pseudo-deficiency reports as low enzyme levels but sulfatide is processed normally so MLD symptoms do not exist. This phenomenon wreaks havoc with traditional approaches to Newborn Screening so new screening methods are being developed.

"For further information, see recessive gene and dominance relationship. Also, consult the MLD genetics page at MLD Foundation."

MLD is directly caused by a deficiency of the enzyme arylsulfatase A (ARSA) and is characterized by enzyme activity in leukocytes that is less than 10% of normal controls. However, assay of the ARSA enzyme activity alone is not sufficient for diagnosis; ARSA pseudodeficiency, which is characterized by enzyme activity that is 5~20% of normal controls does not cause MLD. Without this enzyme, sulfatides build up in many tissues of the body, eventually destroying the myelin sheath of the nervous system. The myelin sheath is a fatty covering that protects nerve fibers. Without it, the nerves in the brain (central nervous system – CNS) and the peripheral nerves (peripheral nervous system – PNS) which control, among other things the muscles related to mobility, cease to function properly.

Arylsulfatase A is activated by saposin B (Sap B), a non-enzymatic proteinaceous cofactor. When the arylsulfatase A enzyme level is normal but the sulfatides are still high – meaning that they are not being broken down because the enzyme is not activated – the resulting disease is saposin B deficiency, which presents similar to MLD. Saposin B Deficiency is very rare, much more rare than traditional MLD. The enzyme that is present is not "enabled" to a normal level of efficiency and can't break down the sulfatides which results in all of the same MLD symptoms and progression.

A recent study contended sulfatide is not completely responsible for MLD because it is nontoxic. It has been suggested lysosulfatide, sulfatide which has had its acyl group removed, plays a role because of its cytotoxic properties in vitro.

Currently, no research has shown a higher prevalence of most leukodsytrophy types in any one place around the world. There is, however, a higher prevalence of the Canavan disease in the Jewish population for unknown reasons. 1 in 40 individuals of Ashkenazi Jewish descent are carriers of Canavan disease. This estimates to roughly 2.5%. Additionally, due to an autosomal recessive inheritance patterns, there is no significant difference found between affected males and affected females for most types of leukodystrophy including, but not limited to, metachromatic leukodystrophy, Krabbe disease, Canavan disease, and Alexander disease. The one exception to this is any type of leukodystrophy carried on a sex chromosome, such as X-linked adrenoleukodystrophy, which is carried on the X-chromosome. Because of the inheritance pattern of X-linked diseases, males are more often affected by this type of leukodystrophy, although female carriers are often symptomatic, though not as severely so as males. To date, there have been no found cases of a leukodystrophy carried on the Y chromosome.

Multiple sulfatase deficiency (also known as "Austin disease", and "mucosulfatidosis") is a very rare autosomal recessive lysosomal storage disease caused by a deficiency in multiple sulfatase enzymes, or in formylglycine-generating enzyme, which activates sulfatases. It is similar to mucopolysaccharidosis.

There are estimated to be approximately 2,000 people afflicted with Hunter syndrome worldwide, 500 of whom live in the United States. There are 2 Hunter syndrome patients in New Zealand, 6 Hunter syndrome patients in Ireland, at least 1 case in Iran, 1 case in Saudi Arabia, 1 case in Chile, 1 case in Pakistan, 20 cases in the Philippines, 1 case in the West Bank (Palestine) and 70 Hunter syndrome patients reported in Korea. There is one case in the city of Kolkata and, as broadcast on local media channel CCN Siliguri on 1 April 2015, a boy in the city of Siliguri, West Bengal, India. In Gangtok, the 8-year-old son of the editor of 'Voice of Sikkim' also suffers from the disease.

A study in the United Kingdom indicated an incidence among males of approximately 1 in 130,000 male live births.

MSD has an autosomal recessive inheritance pattern.

The inheritance probabilities "per birth" are as follows:

- If both parents are carriers:

- 25% (1 in 4) children will have the disorder

- 50% (2 in 4) children will be carriers (but unaffected)

- 25% (1 in 4) children will be free of MSD - unaffected child that is not a carrier

- If one parent is affected and one is free of MSD:

- 0% (0) children will have the disorder - only one parent is affected, other parent always gives normal gene

- 100% (4 in 4) children will be carriers (but unaffected)

- If one parent is a carrier and the other is free of MSD:

- 50% (2 in 4) children will be carriers (but unaffected)

- 50% (2 in 4) children will be free of MSD - unaffected child that is not a carrier

Morquio syndrome (referred to as mucopolysaccharidosis IV, MPS IV, Morquio-Brailsford syndrome, or Morquio) is a rare metabolic disorder in which the body cannot process certain types of mucopolysaccharides. This birth defect, which is autosomal recessive, is thus a lysosomal storage disorder that is usually inherited. In the US, the incidence rate for Morquio is estimated at between 1 in 200,000 and 1 in 300,000 live births.

The build-up or elimination of mucopolysaccharides, rather than processing by their usual biochemical pathways, causes various symptoms. These involve accumulation of keratan sulfate.

Lysosomal storage diseases (LSDs; ) are a group of about 50 rare inherited metabolic disorders that result from defects in lysosomal function. Lysosomes are sacs of enzymes within cells that digest large molecules and pass the fragments on to other parts of the cell for recycling. This process requires several critical enzymes. If one of these enzymes is defective, because of a mutation, the large molecules accumulate within the cell, eventually killing it.

Lysosomal storage disorders are caused by lysosomal dysfunction usually as a consequence of deficiency of a single enzyme required for the metabolism of lipids, glycoproteins (sugar-containing proteins), or so-called mucopolysaccharides. Individually, LSDs occur with incidences of less than 1:100,000; however, as a group, the incidence is about 1:5,000 - 1:10,000. Most of these disorders are autosomal recessively inherited such as Niemann–Pick disease, type C, but a few are X-linked recessively inherited, such as Fabry disease and Hunter syndrome (MPS II).

The lysosome is commonly referred to as the cell's recycling center because it processes unwanted material into substances that the cell can use. Lysosomes break down this unwanted matter by enzymes, highly specialized proteins essential for survival. Lysosomal disorders are usually triggered when a particular enzyme exists in too small an amount or is missing altogether. When this happens, substances accumulate in the cell. In other words, when the lysosome does not function normally, excess products destined for breakdown and recycling are stored in the cell.

Like other genetic disorders, individuals inherit lysosomal storage diseases from their parents. Although each disorder results from different gene mutations that translate into a deficiency in enzyme activity, they all share a common biochemical characteristic – all lysosomal disorders originate from an abnormal accumulation of substances inside the lysosome.

LSDs affect mostly children and they often die at a young and unpredictable age, many within a few months or years of birth. Many other children die of this disease following years of suffering from various symptoms of their particular disorder.

This syndrome has two forms, A and B, referred to as Morquio A and Morquio B syndrome or MPA IVA and MPS IVB. The two forms are distinguished by the gene product involved; A involves a malfunction in the GALNS gene product (galactosamine-6 sulfatase), while B involves a malfunction of the GLB1 gene product (beta-galactosidase).

X-linked recessive inheritance is a mode of inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be expressed in males (who are necessarily hemizygous for the gene mutation because they have one X and one Y chromosome) and in females who are homozygous for the gene mutation, see zygosity.

X-linked inheritance means that the gene causing the trait or the disorder is located on the X chromosome. Females have two X chromosomes, while males have one X and one Y chromosome. Carrier females who have only one copy of the mutation do not usually express the phenotype, although differences in X chromosome inactivation can lead to varying degrees of clinical expression in carrier females since some cells will express one X allele and some will express the other. The current estimate of sequenced X-linked genes is 499 and the total including vaguely defined traits is 983.

Some scholars have suggested discontinuing the terms dominant and recessive when referring to X-linked inheritance due to the multiple mechanisms that can result in the expression of X-linked traits in females, which include cell autonomous expression, skewed X-inactivation, clonal expansion, and somatic mosaicism.

The symptoms of LSD vary, depending on the particular disorder and other variables such as the age of onset, and can be mild to severe. They can include developmental delay, movement disorders, seizures, dementia, deafness, and/or blindness. Some people with LSDhave enlarged livers (hepatomegaly) and enlarged spleens (splenomegaly), pulmonary and cardiac problems, and bones that grow abnormally.

The GM1 gangliosidoses (or GM1 gangliosidos"i"s) are caused by a deficiency of beta-galactosidase, with resulting abnormal storage of acidic lipid materials in cells of the central and peripheral nervous systems, but particularly in the nerve cells.

GM1 Gangliosidoses are inherited, autosomal recessive sphingolipidoses, resulting from marked deficiency of Acid Beta Galactosidase.

The most common X-linked recessive disorders are:

- Red-green color blindness, a very common trait in humans and frequently used to explain X-linked disorders. Between seven and ten percent of men and 0.49% to 1% of women are affected. Its commonness may be explained by its relatively benign nature. It is also known as daltonism.

- Hemophilia A, a blood clotting disorder caused by a mutation of the Factor VIII gene and leading to a deficiency of Factor VIII. It was once thought to be the "royal disease" found in the descendants of Queen Victoria. This is now known to have been Hemophilia B (see below).

- Hemophilia B, also known as Christmas Disease, a blood clotting disorder caused by a mutation of the Factor IX gene and leading to a deficiency of Factor IX. It is rarer than hemophilia A. As noted above, it was common among the descendants of Queen Victoria.

- Duchenne muscular dystrophy, which is associated with mutations in the dystrophin gene. It is characterized by rapid progression of muscle degeneration, eventually leading to loss of skeletal muscle control, respiratory failure, and death.

- Becker's muscular dystrophy, a milder form of Duchenne, which causes slowly progressive muscle weakness of the legs and pelvis.

- X-linked ichthyosis, a form of ichthyosis caused by a hereditary deficiency of the steroid sulfatase (STS) enzyme. It is fairly rare, affecting one in 2,000 to one in 6,000 males.

- X-linked agammaglobulinemia (XLA), which affects the body's ability to fight infection. XLA patients do not generate mature B cells. B cells are part of the immune system and normally manufacture antibodies (also called immunoglobulins) which defends the body from infections (the humoral response). Patients with untreated XLA are prone to develop serious and even fatal infections.

- Glucose-6-phosphate dehydrogenase deficiency, which causes nonimmune hemolytic anemia in response to a number of causes, most commonly infection or exposure to certain medications, chemicals, or foods. Commonly known as "favism", as it can be triggered by chemicals existing naturally in broad (or fava) beans.

A lipid storage disorder (or lipidosis) can be any one of a group of inherited metabolic disorders in which harmful amounts of fats or lipids accumulate in some of the body’s cells and tissues. People with these disorders either do not produce enough of one of the enzymes needed to metabolize and break down lipids or they produce enzymes that do not work properly. Over time, this excessive storage of fats can cause permanent cellular and tissue damage, particularly in the brain, peripheral nervous system, liver, spleen and bone marrow.

Inside cells under normal conditions, lysosomes convert, or metabolize, lipids and proteins into smaller components to provide energy for the body.

Onset of adult GM1 is between ages 3 and 30.

Symptoms include muscle atrophy, neurological complications that are less severe and progress at a slower rate than in other forms of the disorder, corneal clouding in some patients, and dystonia (sustained muscle contractions that cause twisting and repetitive movements or abnormal postures). Angiokeratomas may develop on the lower part of the trunk of the body. Most patients have a normal size liver and spleen.

Prenatal diagnosis is possible by measurement of Acid Beta Galactosidase in cultured amniotic cells.

Specific types of leukodystrophies include the following with their respective ICD-10 codes when available:

- (E71.3) Adrenomyeloneuropathy

- (E75.2) Alexander disease

- (E75.5) Cerebrotendineous xanthomatosis

- Hereditary CNS demyelinating disease

- (E75.2) Krabbe disease

- (E75.2) Metachromatic leukodystrophy

- (E75.2) Pelizaeus–Merzbacher disease

- (E75.2) Canavan disease

- (G93.49) Leukoencephalopathy with vanishing white matter

- (E71.3) Adrenoleukodystrophy

- (G60.1) Refsum disease

X-linked recessive chondrodysplasia punctata is a type of chondrodysplasia punctata that can involve the skin, hair, and cause short stature with skeletal abnormalities, cataracts, and deafness.

This condition is also known as arylsulfatase E deficiency, CDPX1, and X-linked recessive chondrodysplasia punctata 1. The syndrome rarely affects females, but they can be carriers of the recessive allele. Although the exact number of people diagnosed with CDPX1 is unknown, it was estimated that 1 in 500,000 have CDPX1 in varying severity. This condition is not linked to a specific ethnicity. The mutation that leads to a deficiency in arylsulfatase E. (ARSE) occurs in the coding region of the gene.Absence of stippling, deposits of calcium, of bones and cartilage, shown on x-ray, does not rule out chondrodysplasia punctata or a normal chondrodysplasia punctata 1 (CDPX1) gene without mutation. Stippling of the bones and cartilage is rarely seen after childhood. Phalangeal abnormalities are important clinical features to look for once the stippling is no longer visible. Other, more severe, clinical features include respiratory abnormalities, hearing loss, cervical spine abnormalities, delayed cognitive development, ophthalmologic abnormalities, cardiac abnormalities, gastroesophageal reflux, and feeding difficulties. CDPX1 actually has a spectrum of severity; different mutations within the CDPX1 gene have different effects on the catalytic activity of the ARSE protein. The mutations vary between missense, nonsense, insertions, and deletions.

Disorders that store this intracellular material are part of the lysosomal storage diseases family of disorders.