Hunter Syndrome: An Orphan Disease

In the United States, an orphan or rare diseasemake it work. For example, the slippery joint fluid
occurs in less than 200,000 individuals. Also, there arethat lubricates your joints contains
some diseases that only affect that many individualsmucopolysaccharides. The rubbery resilient cartilage in
in the entire world. Than there are those diseasesyour joints is another good example. All bodily tissues
that are widespread in certain parts of the world buthave some of the substance as a normal part of
are rare in others. And there are some diseases thattheir structure.The modern word for
are truly one-of-a kind, usually due to a geneticmucopolysaccharides is glycos-amino-glycans or
defect. The United States Office of Rare Diseases(GAG), which stands for sugar-amino-sugar polymer
(USORD) list over 6,000 diseases considered rare inor long repeating sugar chains found in these
the United States; Hunter Syndrome is one of thosematerials. These sugar chains are submicroscopic and
diseases.Historical Background: The Nationalcannot be seen with the naked eyes, but can be
Mucopolysaccharide Society (MPS) described Hunterstudied using special scientific instruments and
Syndrome as a mucopolysaccharideanalytical methods.To understand how GAG
(muco-poly-saccharide) storage disorder that is alsoaccumulate and cause MPS II, it is important to know
called Mucopolysaccharidosis II (MPS II).Hunterthat in the course of normal life, there is continuous
Syndrome is named after Charles Hunter, a professorprocess of constructing new mucopolysaccharides
of medicine of Manitoba, Canada, who first describedand breaking down old ones; a recycling process.
two brothers with the disorder in 1917. Two types ofInteresting enough, this ongoing process is necessary
Hunter Syndrome have been identified, mild andto keep your body healthy. This process of break
severe. However, there are individuals withdown and recycling requires a series of special
intermediate severity who do not fit neatly in eitherbiochemical tools called enzyme. In order to
the severe or the mild forms of the disease. Studiessuccessful break down GAG, a series of enzymes or
have clearly shown that current understanding of thetools work in sequence one after another to split the
enzyme and its gene demonstrated that MPS IIGAG into pieces. Each enzyme in the process has its
comprises a broad spectrum of severity thatspecial purpose in the body and does just one special
individuals may be diagnosed from severe to mildfunction; like a screwdriver works on screws and a
Hunter with many individuals falling somewhere inhammer works on nails.According to several studies
between.Researchers concluded that all individualsindividuals with MPS II are missing one specific
with Hunter Syndrome have a deficiency of theenzyme called iduronate sulfatase, which is essential in
enzyme iduronate sulfatase, which results in the buildthe process to break down certain GAG called
up of mucopolysaccharides, more recently calleddermatan sulfate and heparin sulfate. The
glycos-amino-glycans (GAG). The accumulation ofincompletely broken down dermatan sulfate and
GAG is responsible for the many problems thatheparin sulfate remain stored inside cells in the body
affect individuals with MPS II.So far, there is no cureand begin to build up, causing progressive damage.
for individuals affected with these disorders.GAG itself is not toxic but the amount of it and the
However, there are means to manage the challengeseffect of storing it in the body leads to multiple
that the individuals will experience, and assist them tophysical problems. Babies may show little sign of the
live a productive life. Several treatments had beendisorder, but as more and more GAG accumulates
tried with limited success. Such as bone marrowsymptoms begin to appear. Sugar or other foods
transplantation with poor results. Currently, enzymenormally eaten will not affect weather there is more
replacement therapy is being studied, which may helpor less build up of GAG.Individuals diagnosed with
some individuals affected with MPS II. ResearchersHunter Syndrome almost always have neurocognitive
continue to look for more effective method to treatdegeneration with progressive and profound mental
these disorders, and hopefully those affected willretardation. When the diagnosis is made in children
have more and better options available in the nearyounger than three years old a progressively severe
future.Even with stem cell transplant or enzymedecline in intellectual functions occurs. Children with
replacement therapy, individuals with MPS II continueMPS II typically have the skeletal changes referred to
to have significant muscular and skeletal disabilities,as dysostosis multiplex. These individuals also exhibits
more commonly involving the spine, hips, knees, andprogressive coarsening of facial features, short
hands. These are rarely life-threatening, butstature, joint stiffness, hepatosplenomegaly, and
frequently limit the individual function, activity, andhernias as common presenting signs and symptoms.
quality of life issues. Surgical intervention is oftenIndividuals inflicted with MPS II may have popular skin
required to optimize long-term function. The timinglesions that are ivory in color and located on the
and type of surgical intervention may vary amongupper back and the lateral upper arms and thighs.
individuals and surgeons. Still, early evaluation isOther skin lesions are hypertrichosis and thickened
important in determining proper treatment, and toskin. And extensive Mongolian spots associated with
optimize quality of life for those affected with MPSHunter Syndrome have also been reported. These
II.How Hunter Syndrome is Inherited: Hunterindividuals tend to have severe mental retardation
Syndrome has a different form of inheritance from alland deafness. Other symptoms include cerebral
other MPS disorders. Hunter Syndrome is a sex-linkedventricular dilation. The facial features of Hunter
disorder, meaning that it is transmitted on the femaleSyndrome are coarse, but the children still have faces
X-chromosome from mother to her children. In whichthat resemble other family members.Mildly affected
case, the syndrome is most often seen in males.children may behave in a normal manner and they
However, rare female cases have been reported.can be quite affectionate with a sunny nature. On
Hunter Syndrome can occur in any ethnic group; butthe other hand, they can become short-tempered
a higher incidence has been reported in the Jewishwhen frustration sets-in due to physical limitations
population living in Israel. Hunter Syndrome may occurwhich often make life very difficult. Children who are
as frequently as one individual per 65, 000 births tomildly affected with MPS II should be encouraged to
as rarely as one individual in 132, 000 births.As statedbe as independent as they can; since many adults
above, girls may be the carriers of the disease butwith Hunter Syndrome lead a relatively normal and
except in the rare case, only boys will be affected.enjoyable life.According to one study done by the
For example, if a woman is the carrier for MPS IINational MPS Society, many mildly affected Hunter
disorder, there is a 50% risk that any male child bornadults have found productive employment as a
to her will be a carrier for the disease. It is veryteacher of the deaf, a marine architect, and another
important to remember that not all women with onlya sergeant in the army. As for education, it is
one MPS II child will be carriers of the abnormal gene.suggested, that some MPS II children could benifit
For instance, if only one individual in a family has MPSfrom having a mainstreamed education enjoying the
II, the carrier status of the birth mother cannot besocial interaction with peers. However, it is very
definitavely determined. However, if additionalimportant that parents and caretakers work closely
affected individuals are known, than the mother ofwith professional educators in the school system and
an MPS II child is assumed to be a carrier.The sistersdevelop the best Individualized Education Program
and maternal aunts of a person with Hunter(IEP) for children with Hunter Syndrome and other
Syndrome may also be carrier of the disorder andrare diseases.Finally, I believe that families, caregivers,
would have a 50% chance of passing the abnormaland educators should go the extra mile to educate
gene to a son. It is strongly suggested that allthemselves about Hunter Syndrome and other rare
families of individuals with Hunter Syndrome shoulddebilitating diseases that inflict children at such an
seek consultation from their medical genetic doctorearly age. However, too often, any developed thirst
or a genetic counselor before planning to havefor knowledge in this area may be left unsatisfied
additional children. It should be noted that analysis ofdue to the lack of information about these diseases
enzyme level, in itself, is not a reliable method toavailable to the public. Nevertheless, this barrier can
determine MPS II carrier status for manybe overcome with the advancement in technology
individuals.What Causes MPS Disorders?and more people are introduced to the Internet.Dr
Mucopolysaccharides are a long chains of sugarWilliam Smith is a psychologist and consultant with
molecules used in the construction of bones, cartilage,many years experience working with individuals and
skin, tendons, and many other tissues in the body.groups. Dr Smith specializes in working with Adult
They form part of the structure of the body andChildren of Alcoholics, and Survivors of Sexual
also give the body many of the special features thatTrauma such as Rape and Incest.