mucolipidosis

Classification

includes four diseases:

• Mucolipidosis 1 (sialidosis)
• Mucolipidosis 2 (I-cell disease) {severe form}
• Mucolipidosis 3 (pseudo-Hurler polydystrophy)
• Mucolipidosis 4 {95% with severe form}

Epidemiology

• some forms are more common among Ashkenazi Jews & French Canadians.

Pathology

• bone & joint damage
• injury to other organs
• peculiar fibroblast inclusions (type 2)
• type 3C retains full transferase activity on synthetic substrates but lacks activity on lysosomal hydrolases (regulatory subunit GNPTG mutation)

Genetics

• mucolipidosis 2 & 3A
  • autosomal recessive
  • caused by mutation in GNPTAB gene
• mucolipidosis 3C
  • autosomal recessive
  • caused by mutation in GNPTG gene
• mucolipidosis 4
  • autosomal recessive
  • caused by mutation in MCOLN1 gene

Clinical manifestations

• mental retardation (may be mild in type 3C)
• impairment in the development of psychomotor skills
• stiff or deformed joints
• short stature
• scoliosis
• claw-like hands
• hip joint deterioration
• fatigue
• abnormalities of the skull & face
  • hyperplastic gums (type 2)
• frequent respiratory infections
• clouding of the cornea
• congenital dislocation of the hip (type 2) severe dysostosis multiplex of the hip (type 3C)

Laboratory

• prenatal screening tests available
  • MCOLN1 genotyping
• no excessive mucopolysacchariduria (type 2)
• elevated serum lysosomal enzyme levels &/or decreased lysosomal enzyme levels in cultured fibroblasts
• see ARUP consult

Management

• treatment is symptomatic
• treat infections
• surgery to correct bone or joint damage
• prognosis
  • based on the severity of the symptoms, which can range from relatively moderate to life threatening
  • some forms of mucolipidoses can be fatal
    • type 2

More general terms

• lipid metabolism, inborn error; lipid storage disease; lipidosis
• lysosomal storage disease

More specific terms

• fucosidosis

Additional terms

• mucolipin-1; MG-2; mucolipidin (MCOLN1 ML4 MSTP080)
• N-acetylglucosamine-1-phosphotransferase (GlcNAc-1-phosphotransferase)
• N-acetylglucosamine-1-phosphotransferase subunits alpha/beta precursor (GNPTAB, GlcNAc-1-phosphotransferase alpha/beta, UDP-N-acetylglucosamine-1-phosphotransferase alpha/beta, stealth protein GNPTAB)

Patient information

mucolipidosis patient information

Database

• OMIM: https://mirror.omim.org/entry/252650
• OMIM: https://mirror.omim.org/entry/252500
• OMIM: https://mirror.omim.org/entry/252600
• OMIM: https://mirror.omim.org/entry/252605