Mucopolysaccharidosis (MPS)

At a glance

It is a large spectrum of disease defined as a metabolic storage condition that affects multiple organs. They are characterized by the absence or malfunctioning of lysosomal enzymes that normally metabolize the glycosaminoglycans. This enzyme is responsible for the lubrification of all tissues, eg, articulations.

Synonym

MPS.

Classification

There are several MPS conditions and subtypes that consist of:

• MPS I H: ☞Hurler Syndrome (Hurler-Pfaundler Syndrome; Johnie McL Syndrome; Thompson Syndrome; Hurler-Scheie Syndrome; Mucopolysaccharide Storage Disease I; α-L-Iduronidase Deficiency Syndrome; Dysostosis Multiplex; Dysostotic Idiocy; Hurler-Pfaundler Syndrome; Gargoylism; Lipochondrodystrophy; Pfaundler-Hurler Syndrome)

• MPS I S: Scheie Syndrome

• MPS I H/S: Hurler-Scheie Syndrome

• MPS II: ☞Hunter Syndrome (Hurler-Hunter Disease; Mucopolysaccharide Storage Disease II)

• MPS III: Sanfilippo Syndrome (Mucopolysaccharide Storage Disease III; Heparitinuria; HS-Mucopolysaccharidosis; Polydystrophic Oligophrenia)

  • Type A: Sanfilippo Syndrome A (Heparan Sulfate Sulfatase Deficiency)

  • Type B: Sanfilippo Syndrome B (N-Acetyl-Alpha-D-Glucosaminidase [NAG] Deficiency)

  • Type C: Sanfilippo Syndrome C (Acetyl-CoA-Alpha-Glucosamide N-Acetyltransferase Deficiency)

  • Type D: Sanfilippo Syndrome D (N-Acetylglucosamine-6-Sulfate Sulfatase Deficiency)

• MPS IV: ☞Morquio Syndrome (Mucopolysaccharide Storage Disease IV; Morquio-Brailsford Syndrome; Morquio-Ullrich Syndrome; Atypical Chondrodystrophy; Dysostosis Enchon­dralis Metaepiphysaria; Eccentrochondrodysplasia; Eccentro-Osteochondrodysplasia; Familial Osseous Dystrophy; Hereditary Chondrodysplasia; Hereditary Osteochondrodystrophy; Hereditary Polytopic Enchondral Dysostosis; Keratansulfaturia; KS Mucopolysaccharidosis; Osteochondrodystrophia Deformans; Osteochondrodystrophy; Spondylo-Epiphyseal Dysplasia; Silfverskiold Syndrome; Morquio-Silfverskiold Syndrome)

  • Type A: Morquio Syndrome A (Galactosamine-4-Sulfatase [GALNS] Deficiency)

  • Type B: Morquio Syndrome B (Morquio-Like Syndrome; β-Galactosidase Deficiency)

• MPS V: Obsolete, previously known Ellis-Sheldon Syndrome

• MPS VI: Maroteaux-Lamy Syndrome (Mucopolysaccharide Storage Disease VI; Arylsulfatase B [ARSB] Deficiency; N-Acetylgalactosamine-4-Sulfatase Deficiency; Polydystrophic Dwarfism; Pyknodysostosis of Maroteaux-Lamy)

• MPS VII: Sly Syndrome (Mucopolysaccharide Storage Disease VII; Beta-Glucuronidase Deficiency; Beta-Glucuronidase Deficiency Mucopolysaccharidosis; GUSB Deficiency)

• MPS VIII: ☞Di Ferrante Syndrome

  • N.B.: Di Ferrante Syndrome should not be used as a term to describe MPS VIII because it has been proved that the author committed fraud based on observation obtained from only one patient.

• MPS F: ☞Fucosidosis (Mucopolysaccharide Storage Disease F; α-L-Fucosidase [FUCA] Deficiency)

Incidence

The incidence of MPS is estimated at 0.04 to 0.3% of living births and considered 1.5% of all congenital disorders. The average surviving for these patients is around 20 to 30 years and cardiac failure or infections to the gastrointestinal tract cause death. The instability to the atlantoaxial joint is also implicated as cause of death.

Genetic inheritance

MPS I and III are autosomal recessive; MPS II is X-linked with locus at Xq27-q28; MPS IV is autosomal recessive and located on chromosome 16 long arm; MPS VI is autosomal recessive; MPS VII is autosomal recessive, with GUSB locus on long arm of chromosome 7; fucosidosis is an autosomal recessive trait with occasional parental consanguinity, located on the short arm of chromosomes 1 and 2.

Pathophysiology

MPS I: Inborn error of mucopolysaccharide metabolism with α...