What is the Disease?
- lysosomal storage disease
- progressively debilitating disorder that affects different parts of the body
- enzyme iduronate 2-sulfatase missing, which is responsible for breaking down large sugar molecules, called dermatan and heparan
- buildup of these sugar molecules causes damage to body
How was it Discovered?
- 1917 by Charles Hunter
- described his two brothers with the disease
Incidence Rate
Hunter syndrome affects about 1 in 25,000 babies born in the United States. Globally, it affects about 1 in 100,000 to 150,000 people. It typically is only found in males because they only have one X chromosome, which is where the mutated gene, IDS is located. Females have been known to inherit Hunter Syndrome, but because it is a recessive trait and they have two X chromosomes, their incidence rate is significantly lower, unless they are born with two altered copies of the IDS gene.
Location of IDS gene
Symptoms
- full lips
- large rounded cheeks
- broad nose
- enlarged tongue (macroglossio)
- deep, hoarse voice
- sleep apnea
- large head (macrocephaly)
- fluid in the brain (hydrocephalus)
- enlarged liver and spleen
- umbilical and abdominal hernias
- white skin growths
- hearing loss/ear infections
- reduced vision
- carpal tunnel syndrome
- heart valve problems
Diagnosis
- documentation of reduced or absent iduronate 2-sulfatase enzyme activity from blood or skin cells
- patients accumulate heparin and dermatan sulfates in urine
- molecular testing available to confirm diagnosis
Prognosis
- no cure
- severe cases-lifespan 10-20 years
- mild cases-lifespan 20-60 years
Treatment
- enzyme replacement therapy-replacing patients' deficient/absent enzyme with working enzyme via IV
- other treatment is purely symptomatic (only treat symptoms of disease)
Research
In 2010, researchers began studying the use of intrathecal injections (into the spine) using a more concentrated dose of idursulfase than the one used in IVs in enzyme replacement therapy. They hope to prevent the cognitive decline associated with the condition.
