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Mucopolysaccharidoses (MPS) - Type 2

Name of disease:

Mucopolysaccharidoses (MPS) - Type 2

ICD-10 diagnosis code:

E76.1

Causes:

Metabolic disorders Caused by a mutation in the IDS (Iduronate 2-sulfatase) gene deficiency. IDS deficiency leads to primary accumulation of dermatan sulfate (DS) and heparan sulfate (HS). MPS II is both multi-systemic and progressive. Phenotypes are classified as either attenuated or severe (based on absence or presence of central nervous system impairment, respectively)

Mode of inheritance:

inherited in an X-linked recessive pattern, which means that this condition occurs almost exclusively in males

Prevalence:

1-9 / 1 000 000 in Europe is 1/166,000

Diagnosis:

Diagnosis requires documentation of reduced or absent iduronate 2-sulfatase enzyme activity in blood or skin cells. A very simple determination of glycosaminoglycans in the urine may help in screening potential positive patients. Patients with MPSII disease accumulate heparin and dermatan sulfates in the urines. Molecular genetic testing for mutations in the IDS gene is available to confirm the diagnosis.

Age of onset:

Childhood

Common signs and symptoms:

MPS2 patients appear healthy at birth, with initial symptoms appearing between 18 months and 4 years of age. Macrocephaly develops during infancy and infants initially grow at normal or above average rates. Initial manifestations include: frequent respiratory tract infections (in particular otitis media); umbilical and inguinal hernia; intractable diarrhea; hepatosplenomegaly; skin lesions resembling an orange peel (on the shoulder, back and thighs). Distinctive facies with thickening of lips and nostrils as well as an enlarged and protruding tongue forms slowly and may become evident between 2-4 years of age, later in attenuated cases. Progression varies from a severe form (MPS2, severe form) with early psychomotor regression to an attenuated form (MPS2, attenuated form) which manifests without cognitive involvement.

Available treatments (medicinal and non-medicinal):

Conventional ERT and HSCT coupled with surgical intervention and palliative therapy are currently the treatment options available to MPS II patients. intravenous enzyme replacement therapy (ERT),weekly intravenous enzyme replacement therapy (ERT) which has been shown to alleviate somatic symptoms. Idursulfase (Brand name: Elaprase®) - improve walking capacity in these patients hematopoietic stem cell transplantation (HSCT), anti-inflammatory treatment, and palliative care with symptomatic surgeries. 1. Cranial shunting should be performed to relieve cases of hydrocephalus. 2. Hernia repair, 3. tonsillectomy and adenoidectomy (to liberate the upper respiratory tract infection) 4. in some cases, positive pressure ventilation or tracheostomy may be required. 5. Cardiac valve or hip replacement and carpal tunnel release may be necessary over time.

Disease management tips:

Hong Kong Mucopolysaccharidose & Rare Genetic Diseases Mutual Aid Group Prognosis is highly variable. In the severe form (60-80% of cases) intellectual deficits, life expectancy is markedly reduced, death generally occurring before the age of 25 often as a result of cardio-respiratory complications. In the attenuated form, patients may survive into adulthood, sometimes even beyond the age of 60, and intellectual deficits are most often absent in these cases. Extensive palliative care is required, patients must be regularly evaluated by echocardiogram, respiratory function, full radiologic examination to identify dysostosis multiplex, cranial and cervical MRI with or without lumbar puncture to assess cerebrospinal fluid pressure, hearing tests, eye exams and nerve conduction velocity tests.

References:

https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=EN&Expert=580 GARD NORD https://rarediseases.org/rare-diseases/mucopolysaccharidosis-type-ii-2/

Other useful websites:

More about the disease:https://pubmed.ncbi.nlm.nih.gov/29158997/ Patient groups:（英語群組）