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.

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.

MPS IV, Morquio syndrome, is estimated to occur in 1 in 700,000 births. Its two subtypes result from the missing or deficient enzymes N-acetylgalactosamine-6-sulfatase (GALNS) (Type A) or beta-galactosidase (Type B) needed to break down the keratan sulfate sugar chain. Clinical features are similar in both types but appear milder in Morquio Type B. Onset is between ages 1 and 3. Neurological complications include spinal nerve and nerve root compression resulting from extreme, progressive skeletal changes, particularly in the ribs and chest; conductive and/or neurosensitive loss of hearing and clouded corneas. Intelligence is normal unless hydrocephalus develops and is not treated.

Physical growth slows generally around the age of 18 months, and stops completely by the age of 8. Skeletal abnormalities include a bell-shaped chest, a flattening or curvature of the spine, shortened long bones, and dysplasia of the hips, knees, ankles, and wrists. The bones that stabilize the connection between the head and neck can be malformed (odontoid hypoplasia); in these cases, a surgical procedure called spinal cervical bone fusion can be lifesaving. Restricted breathing, joint stiffness, and heart disease are also common. Children with the more, severe form of Morquio syndrome may not live beyond their twenties or thirties. The oldest known living person with Morquios Type IV A Kenneth D. Martin died Sept. 20 2016 at Mesa, Ariz. from complications of Morquio Syndrome. He was 81, and was born in Osage City, Kansas, USA.

Roberts syndrome is an extremely rare condition that only affects about 150 reported individuals. Although there have been only about 150 reported cases, the affected group is quite diverse and spread worldwide. Parental consanguinity (parents are closely related) is common with this genetic disorder. The frequency of Roberts syndrome carriers is unknown.

Sly syndrome, also called mucopolysaccharidosis type VII (MPS 7), is an autosomal recessive lysosomal storage disease characterized by a deficiency of the enzyme β-glucuronidase, a lysosomal enzyme. Sly syndrome belongs to a group of disorders known as mucopolysaccharidoses, which are lysosomal storage diseases. In Sly syndrome, the deficiency in β-glucuronidase leads to the accumulation of certain complex carbohydrates (mucopolysaccharides) in many tissues and organs of the body.

It was named after its discoverer William S. Sly, an American biochemist who has spent nearly his entire academic career at Saint Louis University.

Vestronidase alfa-vjbk (Mepsevii) is the only drug approved by U.S. Food and Drug Administration for the treatment of pediatric and adult patients.

Nevo Syndrome is considered to be a rare disorder. Since its first appearance in 1974, only a handful of cases have been reported. Studies have shown showing similarities between Nevo Syndrome with Ehlers-Danlos syndrome as well as Sotos syndrome. There is an astounding overlap of phenotypic manifestations between Nevo Syndrome and the more frequent Sotos syndrome, which are both caused by the NSD1 deletion. Sotos syndrome is an autosomal dominant condition associated with learning disabilities, a distinctive facial appearance, and overgrowth. Studies have shown an overwhelming occurrence (half of those involved in the study) of Nevo syndrome in those individuals of Middle-Eastern descent.

Pearson Syndrome is a very rare mitochondrial disorder that is characterized by health conditions such as sideroblastic anemia, liver disease, and exocrine pancreas deficiency.

Pseudo-Hurler polydystrophy, also referred to as mucolipidosis III (ML III), is a lysosomal storage disease closely related to I-cell disease (ML II). This disorder is called Pseudo-Hurler because it resembles a mild form of Hurler syndrome, one of the mucopolysaccharide (MPS) diseases.

At this time, there are no other phenotypes (observable expressions of a gene) that have been discovered for mutations in the ESCO2 gene.

If the Hirschsprung's disease is treated in time, ABCD sufferers live otherwise healthy lives. If it is not found soon enough, death often occurs in infancy. For those suffering hearing loss, it is generally regressive and the damage to hearing increases over time. Digestive problems from the colostomy and reattachment may exist, but most cases can be treated with laxatives. The only other debilitating symptom is hearing loss, which is usually degenerative and can only be treated with surgery or hearing aids.

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.

Nevo Syndrome is an autosomal recessive disorder. Most times in which a child is afflicted with Nevo Syndrome, both their parents are of average height and weight. It is only until after birth when the characteristic physical traits associated with disease are manifested, and the disorder is actually diagnosed. One study showed that despite the increased growth rates, the patient was completely healthy up until age 6, when he was admitted into the hospital. Nevo syndrome is usually associated with early childhood fatality. Children with Nevo Syndrome have a high occurrence of death due to cardiac arrest because their developing hearts cannot keep up with their overgrown body.

Children with Maroteaux–Lamy syndrome usually have normal intellectual development but share many of the physical symptoms found in Hurler syndrome. Caused by the deficient enzyme N-acetylgalactosamine 4-sulfatase, Maroteaux–Lamy syndrome has a variable spectrum of severe symptoms. Neurological complications include clouded corneas, deafness, thickening of the dura (the membrane that surrounds and protects the brain and spinal cord), and pain caused by compressed or traumatized nerves and nerve roots.

Signs are revealed early in the affected child's life, with one of the first symptoms often being a significantly prolonged age of learning how to walk. By age 10 children have developed a shortened trunk, crouched stance, and restricted joint movement. In more severe cases, children also develop a protruding abdomen and forward-curving spine. Skeletal changes (particularly in the pelvic region) are progressive and limit movement. Many children also have umbilical hernia or inguinal hernias. Nearly all children have some form of heart disease, usually involving valve dysfunction.

An enzyme replacement therapy, galsulfase (Naglazyme), was tested on patients with Maroteaux–Lamy syndrome and was successful in that it improved growth and joint movement. An experiment was then carried out to see whether an injection of the missing enzyme into the hips would help the range of motion and pain. At a cost of $365,000 a year, Naglazyme is one of the world's most expensive drugs.

I-cell disease is an autosomal recessive disorder caused by a deficiency of GlcNAc phosphotransferase, which phosphorylates mannose residues to mannose-6-phosphate on N-linked glycoproteins in the Golgi apparatus within the cell. Without mannose-6-phosphate to target them to the lysosomes, the enzymes are transported from the Golgi to the extracellular space, resulting in large intracellular inclusions of molecules requiring lysosomal degradation in patients with the disease (hence the name of the disorder). Hydrolases secreted into the blood stream cause little problem as they are deactivated in the neutral pH of the blood.

It can be associated with GNPTA.

In a case report, it was complicated by severe dilative cardiomyopathy(DCM)

Though rare, a deficiency of phosphodiesterase which would cleave GlcNAc from the Mannose 6 Phosphate tag will also cause I-Cell. The presence of lipids, glycosaminoglycans (GAG's) and carbohydrates in the blood provide for the distinguishing characteristic to separate I-Cell from Hurlers Syndrome, in Hurlers, only glycosaminoglycans would be present.

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.

Because oculocerebrorenal syndrome is an X-linked recessive condition, the disease develops mostly in men with very rare occurrences in women, while women are carriers of the disease; it has an estimated prevalence of 1 in 500,000 people. Boys with Lowe syndrome are born with cataracts in both eyes, glaucoma is present in about half of the individuals with Lowe syndrome, though usually not at birth. While not present at birth, many affected boys develop kidney problems at about one year of age. Renal pathology is characterized by an abnormal loss of certain substances into the urine, including bicarbonate, sodium, potassium, amino acids, organic acids, albumin, calcium and L-carnitine, this problem, is known as Fanconi-type renal tubular dysfunction.

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.

Respiratory complications are often cause of death in early infancy.

Pearson syndrome is a mitochondrial disease characterized by sideroblastic anemia and exocrine pancreas dysfunction. Other clinical features are failure to thrive, pancreatic fibrosis with insulin-dependent diabetes and exocrine pancreatic deficiency, muscle and neurologic impairment, and, frequently, early death. It is usually fatal in infancy. The few patients who survive into adulthood often develop symptoms of Kearns-Sayre syndrome.

It is caused by a deletion in mitochondrial DNA. Pearson syndrome is very rare, less than hundred cases have been reported in medical literature worldwide.

The syndrome was first described by pediatric hematologist and oncologist Howard Pearson in 1979; the deletions causing it were discovered a decade later.

Maroteaux–Lamy syndrome (also known as mucopolysaccharidosis type VI, MPS VI, or polydystrophic dwarfism) is a form of mucopolysaccharidosis caused by a deficiency in arylsulfatase B (ARSB). It is named after Pierre Maroteaux (1926–) and his mentor Maurice Emil Joseph Lamy (1895–1975), both French physicians.

Oculocerebrorenal syndrome (also called Lowe syndrome) is a rare X-linked recessive disorder characterized by congenital cataracts, hypotonia, intellectual disability, proximal tubular acidosis, aminoaciduria, and low-molecular-weight proteinuria. Lowe syndrome can be considered a cause of Fanconi syndrome (bicarbonaturia, renal tubular acidosis, potassium loss, and sodium loss).

Scheie syndrome (also known as "MPS I-S") is less severe version of Hurler syndrome. It is a condition characterized by corneal clouding, facial dysmorphism, and normal lifespan. People with this condition may have aortic regurgitation.

Marshall–Smith syndrome is not to be confused with:

- Marshall syndrome (aka.Periodic fever, aphthous stomatitis, pharyngitis and adenitis (PFAPA syndrome, see also: Periodic fever syndrome)

- Sotos (like) syndrome

- Weaver-Smith syndrome (WSS)