What Happens
When Cystine
Control Fades
Away...
KNOW CYSTINOSIS
A Guide for Patients,
Parents, and Caregivers
www.knowcystinosis.com
What is cystinosis?
1,2
THERE ARE 3
1
FORMS OF CYSTINOSIS
1
Nephropathic (neff-ROH-path-ik) cystinosis
Accounts for around 95% of cystinosis
cases. It is the most severe form of the
disease. Symptoms typically appear
within a baby’s first year
Cystinosis is a medical condition that results in the buildup of
cystine, an amino acid, in the body’s cells. Without treatment,
cystine rapidly builds up to toxic levels. The body needs a way to
keep depleting (removing) cystine. Otherwise, serious damage to
organs and tissues can occur.
Cystinosis is rare—it is estimated that only about 500 people
in the United States and 2,000 people worldwide have been
diagnosed.3 Medical experts are still learning more about it.
However, the following are some key facts:
Cystinosis is a genetic disease4,5
Know what you can do
2
Starts in the teenage years
This means it is a condition that runs in families. It is not
something contagious. It’s in your genes. Your genes carry the
information that tells each cell in your body what to do. For
instance, genes carry the codes for eye and hair color.
Non-nephropathic or ocular cystinosis
We each have thousands of genes. Sometimes, a gene is changed
from the normal form. This is called a mutation. When mutated
genes are passed on from parents to children, they can raise
the risk of certain diseases. In cystinosis, a mutation in the gene
called cystinosin (CTNS) causes a problem with the body’s ability
to transport cystine out of the cells.
Intermediate cystinosis
Living with cystinosis affects you, your family, and others who care about you. But today,
with the right care, someone with this rare and serious condition may live a longer, healthier
life. New treatments, new knowledge, and new sources of community support have become
available. The outlook for people with cystinosis is getting brighter.
This booklet provides some facts about cystinosis—and the ways you can better manage it.
Read on for information and practical tips that may help you along the way.
2
Know Cystinosis
3
Is marked by symptoms such as the
formation of crystals in the cornea and
sensitivity to light
A Guide for Patients, Parents, and Caregivers
3
Cystinosis is a metabolic disease4
Know the facts
Metabolism is your body’s way of making, using, and storing energy. It’s
a process that takes place inside every cell in your body—including your
muscles, bones, organs, and nerves. When any part of this process is
interrupted, it can alter the way your body works.
Some genes control your body’s metabolism. For instance, CTNS affects a
transporter protein (cystinosin) that plays a role in the way your cells digest
and recycle materials. A mutation of this gene causes cystinosis—and can
trigger problems that disrupt your body’s normal metabolism.
Cystinosis is a multi-organ progressive disease1,2
Cystinosis affects many organs, including your kidneys, eyes, stomach,
intestines, muscles, and brain. Without treatment, cystinosis can continue
to damage your body. With consistent treatment, however, much of the
damage may be slowed down or delayed.
4
Know Cystinosis
• Cystinosis is a rare genetic
disease in which cystine, an
amino acid, builds up to
toxic levels in the cells
• Of the 3 forms of cystinosis,
nephropathic cystinosis
is the most common
and severe
• Cystinosis is relentless.
Without treatment, this
multi-organ, progressive
condition continues to
cause damage throughout
the body
A Guide for Patients, Parents, and Caregivers
5
A look inside the cell
6,7
Everything that happens in the body starts in your cells. Think of them as tiny factories that create and use
energy to power your muscles, nerves, organs, and everything else in your body.6
As small as they are, cells contain even smaller units (called organelles) that carry out important functions.
One of those organelles is the lysosome. Think of it as a cell’s recycling center—where powerful enzymes
break down proteins and other cellular matter.
Proteins are broken down into different amino acids. Then specific transporters move the amino acids out
of the lysosome. One of those amino acids is cystine.
CELL DIAGRAM
NORMAL LYSOSOME
In a normal lysosome, cystine is transported out of the lysosome naturally.
In people with cystinosis, the transporter for cystine does not work. As a
result, cystine builds up rapidly in just hours. Toxic levels of cystine are
stored in the lysosome—which causes serious damage to the cells.2 (This
is why cystinosis is called a lysosomal storage disorder.)
Fortunately, researchers have found that by depleting the cells (or moving
cystine out of the lysosome), cystine levels can be kept under control.2
CELL DAMAGED WITH CYSTINOSIS
CYSTINE
Know the facts
• Cystinosis is a lysosomal
storage disorder. This means
there can be rapid and
constant buildup of cystine
inside the lysosome
• Cystine needs to be moved
out of the lysosome
continuously. Otherwise,
toxic levels of cystine
continue to cause serious
cell damage
OTHER AMINO ACID
CRYSTALS
In a normal lysosome, cystine and other
amino acids are transported out through
their respective transporters.
6
Know Cystinosis
In people with cystinosis, the transport system does not
work properly. Cystine is trapped in the lysosome. It
builds up and forms crystals that can damage the cell.
A Guide for Patients, Parents, and Caregivers
7
If a doctor suspects that a child might have cystinosis1
He or she may do the following:
How is cystinosis diagnosed?
Nephropathic cystinosis symptoms typically appear within a baby’s first year.8
If you have been diagnosed with cystinosis, you may have had normal length and
weight when you were born. But you may have started to fall behind in your growth
during your first year. This is called failure to thrive. Failure to thrive can be caused
by problems such as poor appetite, feeding problems, or vomiting a lot. Other
symptoms—urinating more frequently or being thirsty all the time—may have
started as well. All this may have alerted your parents and doctors to find out why.
Check the child’s eyes for crystals in the cornea
Confirm the diagnosis by doing a special blood test called a white blood cell (WBC) cystine test.
This test measures how much cystine has built up in the blood cells. Normal cystine levels are
about 0.2 nmol ½ cystine/mg of protein.9 A child with cystinosis can have up to 100 times the
normal level
Genetic testing and diagnosis8
Researchers have learned which gene is responsible
for causing cystinosis. If a woman who has a child with
cystinosis becomes pregnant again, tests can be done
to find out if her next child carries the gene mutation.
This is called prenatal diagnosis.
Is there a genetic
counselor in your area?
A genetic counselor may
help you better understand
mutations, cystinosis, and
your family history.
Visit the website of the
National Society of
Genetic Counselors
at www.nsgc.org.
8
Know Cystinosis
A Guide for Patients, Parents, and Caregivers
9
Cystinosis and your family history
5,10,11
carrier father
carrier mother
Cystinosis can affect people of all races and
Know the facts
ethnic backgrounds
12,13
Neither of your parents may have cystinosis themselves.
But, if you have it, this means both your parents are
carriers. That is, they have the gene mutation for cystinosis,
which they inherited from their parents.
Cystinosis runs in families, but it is not predictable. In fact,
it is almost always a surprise to parents when their child is
diagnosed. That’s because neither parent may have ever
had any symptoms of cystinosis.
affected
unaffected
carrier
In the United States, cystinosis is commonly found in blond, blue-eyed
children of Northern European heritage. For example, the risk of cystinosis
may be higher if the family’s roots can be traced back to France, Germany, or
the United Kingdom.
However, people from other ethnic groups (African Americans, Asians, Italians,
and Mexicans) may also be affected with cystinosis because of certain CTNS
gene mutations passed on in their families.
• Cystinosis is caused by a
gene mutation passed on
from parents to children
• Genetic testing is one way
to find out about the risk of
cystinosis in the family
If you’re concerned about a risk of cystinosis in your family, you may want to
talk with a genetic counselor. A genetic counselor can advise you and your
family on genetic tests and explain your options.
When both parents carry the affected gene
This example shows how the CTNS gene mutation may be
passed on to children when both parents are carriers.
One child will
have cystinosis
(25% chance)
2 children will not have
cystinosis but will be
carriers (50% chance)
One child will not have
cystinosis nor be a
carrier (25% chance)
This is only an example. Each family’s history is different and cystinosis
may affect male or female children.
10
Know Cystinosis
A Guide for Patients, Parents, and Caregivers
11
1
2
Problems often caused by cystinosis
3
&
Signs
symptoms
1 Learning and memory problems
2 Sensitivity to light, vision problems
4
5
8
3 P
roblems swallowing,
dehydration, increased thirst
4 Muscle weakness
6
5 L
ung and breathing problems
7
6 F
anconi syndrome (a type of kidney disorder),
other kidney problems, increased urination
8
?
How cystinosis affects the body
Cystinosis is a multi-organ disease. Cystine quickly
builds up in different organs and parts of your body,
including your 2:
• Kidneys
• Muscles
7 S
tomach and intestinal problems
• Liver
• Brain
8 Bone weakness (rickets)
• Spleen
• Bone marrow
• Lymph nodes
• Cognitive impairment
and neurological
disorders
• Thyroid
• Intestines
What is dehydration?14
Dehydration happens when
the body loses too
much water.
12
Know Cystinosis
A Guide for Patients, Parents, and Caregivers
13
CYSTINOSIS AFFECTS MANY ORGANS
When cystinosis is not treated,
damage to many organs
continues over time
Age when symptoms may start2
Common symptoms and
health problems related
to cystinosis
KIDNEYS
GROWTH
BONES
STOMACH AND
INTESTINES
EYES
MUSCLES
6 to 12 months
6 to 12 months
6 to 12 months
1 to 12 years16
13 to 40 years
12 to 40 years
Many cystinosis symptoms are
related to kidney problems. For
instance, one of the first symptoms
seen in children is a kidney disorder
called Fanconi syndrome. In Fanconi
syndrome, nutrients and minerals
that the body needs are released
into the urine.2
• Increased urination
• Dehydration
• Severe thirst
Infants and children with
untreated cystinosis may
be shorter and smaller than
other children their age.
This is due largely to organ
damage, nutrient loss, and
bone disease.8
• Bone weakness (rickets)
caused by the loss of
nutrients, especially
phosphate. May result
in soft, bowed bones
especially in the legs15
• Nausea
• Vomiting
• Heartburn
• Acid reflux17
Cystine crystals can form in
the eyes and reflect light.
So bright light of any kind
can cause pain.15,17
• Sensitivity to light
(photophobia)
• Adult patients may
have muscle
weakness and wasting
(myopathy)15,17
• Trouble swallowing
and breathing
• Slowed growth (failure to
thrive) in children
• Delayed development of
facial bones and teeth
• Delayed puberty
14
Know Cystinosis
A Guide for Patients, Parents, and Caregivers
15
Helping to manage cystinosis with
supportive treatment
Ongoing treatment now makes it possible for cystinosis patients to live
longer. Consistent care is so important—even when you look or feel
fine. Cystinosis does not rest. And when you delay, miss, or stop taking
medicine, cystine levels can rise very quickly.18
Different medicines are often needed to manage the many signs
and symptoms of cystinosis. Doctors often prescribe or recommend
medicines based on each person’s medical needs. In fact, people
with cystinosis report taking an average of 7 different medicines or
supplements, and some may take as many as 14.19
You may need many treatments because cystinosis affects many parts of
your body. Make sure you work closely with your doctor. Ask questions
and share your concerns. And, of course, talk about any symptoms you
have. Early treatment of symptoms may lead to better results.
16
Know Cystinosis
Know the facts
• The damage caused by toxic
levels of cystine cannot be
reversed. That’s why it’s
important to keep cystine
levels under constant control9
• A kidney transplant is not
a cure for cystinosis. After
a transplant, it’s important
to continue with treatment
to care for other organs in
the body9
A Guide for Patients, Parents, and Caregivers
17
Your healthcare team
Cystinosis affects many parts of the body. That’s why you may have a team
of experts to help you at different times over the course of your life.5,17
Nephrologist
Gastroenterologist
(card-ee-OL-o-jist)
• Specializes in caring
for the heart
and blood vessels
Endocrinologist
• Manages thyroid issues
and diabetes
• May prescribe growth
hormone therapy
for children with
cystinosis
Know Cystinosis
• Specializes in the kidneys
• Specializes in the stomach
and intestines
(en-doh-krin-OL-o-jist)
18
(neff-ROL-o-jist)
(gas-tro-en-ter-OL-o-jist)
Cardiologist
• Manages problems related
to eating, including
problems with
swallowing
Internist/general
physician
• Specializes in the
internal organs
• Provides general
medical care for adults
• For children, a pediatric
nephrologist often makes
the initial diagnosis and
directs medical care
throughout the
teenage years
Ophthalmologist
Transplant surgeon/
transplant team
• Specializes in the eyes,
including problems with
the cornea and retina
• Performs transplant
surgery and provides care
before, during,
and after surgery
(off-thal-MOL-o-jist)
Neurologist
(nyur-OL-o-jist)
• Specializes in nerve and
muscle problems, which
usually appear in the
late teenage years
Pediatrician
(pee-dee-uh-TRISH-un)
• Provides general
medical care
for children
Other experts
• Child life specialists,
dietitians, psychologists,
social workers, and
therapists may also help
in your care
A Guide for Patients, Parents, and Caregivers
19
Treating cystinosis
The main goal of treatment is to help slow the progression of cystinosis. It is important to:
Know the facts
• Begin treatment as soon as possible
• Follow your treatment plan carefully
It’s important to be consistent with your medicine. Know your exact doses and when you have
to take them. This helps ensure you have consistent cystine control. This may even help to slow
the progression of kidney disease and delay kidney failure—and help prevent problems with
other organs.9,17
In addition to the main medicines you’re taking, your doctor may also recommend WBC cystine
testing to help you see any changes in cystine levels. Most doctors advise keeping cystine levels to
less than 1 nmol ½ cystine/mg of protein.7 Your doctor may advise regular WBC cystine tests—
every 3 or 4 months.20,21
20
Know Cystinosis
WBC cystine test results can help you and
18,22
your doctor :
Find out how well your medicine is working to maintain
your target cystine level
See whether your medicine dose needs to be adjusted
What is a WBC cystine test? 23
This special blood test tells you
what your cystine levels are by
measuring how much cystine has
built up in your white blood cells.
A Guide for Patients, Parents, and Caregivers
21
Know the facts
When a kidney transplant may be needed
5
As kidney function weakens, you may eventually need a transplant.
A transplant can help restore kidney function. Some people may
need more than one transplant surgery. After the kidney transplant
surgery, a group of medical specialists usually team up to help you
manage any other health problems related to cystinosis. You will
also need to take medicines called immunosuppressants. These
medicines work to keep your body’s immune system from rejecting
the donor kidney.
22
Know Cystinosis
You will still need
cystinosis medicine after
a kidney transplant1,9
The kidneys may be the first to
be affected, but cystinosis is not
just a kidney problem. Even after
a transplant, other parts of your
body continue to be damaged
when cystine levels rise. That’s
why you still need to keep taking
your cystinosis medicine. Staying
with your medicine routine after
transplant surgery may also help
you care for your new kidney.
A Guide for Patients, Parents, and Caregivers
23
Living with cystinosis
Action steps for parents and caregivers
Cystinosis can take its toll on you and your family. There are so many day-to-day demands—
coping with the disease and managing medicines and side-effects. You do your best to take
care of yourself even with these concerns. But with the right support—and careful choices
for your health—you may still have a good, full life. One of the most important steps you can
take is to stay on your treatment plan. This may include:
• Talking openly with your doctor, being aware of your cystine levels,
and staying informed about options to help manage cystinosis
For parents who have just found out their child has cystinosis, coming to terms with the diagnosis
can be very hard.5 Parents may feel sadness because their son or daughter may have a different
childhood from what they had hoped. Even with these many challenges, parents and caregivers can
take steps to help children with cystinosis live fulfilling lives.
Step 1
• Taking a variety of medicines and supplements to help with different
health concerns related to cystinosis
When you know more about cystinosis, you’ll see how important it is
to keep up with the treatment.
Be consistent.
Keep up your cystinosis
treatment to help
prevent or delay future
health problems.
Explaining how medicine helps
5
Future problems (such as kidney disease and kidney failure) may be hard for
children and teens to grasp. Parents and caregivers can help them think about
long-term health by giving examples of what may happen when medicine doses
are missed. For instance, missing doses now could lead to physical problems later.
And that may affect future plans—such as playing sports, learning to drive, or
getting a job. Consider how a child or teen feels, and respect his or her opinions.
Parents and caregivers may also work together with the healthcare team to find a
medicine routine that’s easier for their children to follow.
Source: Cystinosis Research Network
24
Know Cystinosis
A Guide for Patients, Parents, and Caregivers
25
Step 2
Building self-reliance and self-esteem
5
With cystinosis, a child’s life may be filled with medical appointments,
treatment schedules, and so on. But it’s important to encourage the
“regular” things, too. Activities with the family, time with friends, playing
team sports, and even doing everyday chores may all help children and
teens build self-reliance and self-esteem. This can go a long way toward
helping them grow into responsible, capable adults.
Step 3
Preparing children and teens for self-care
5
As children get older, parents and caregivers can help them learn about self-care.
For a teen, being more responsible for his or her care is an important step to
independence. A teen is already coping with the regular changes and challenges of
growing up. At the same time, he or she is also becoming more aware that cystinosis
is a life-long condition. Parents and caregivers may want to seek advice from a social
worker or behavior expert to help their teens move forward. Some ways to encourage
self-care for teens include5:
• Explaining cystinosis and how it affects the body
• Providing a view of how treatment helps
• Working with their teen on a practical plan for staying on track with medicines
Source: Cystinosis Research Network
26
Know Cystinosis
A Guide for Patients, Parents, and Caregivers
27
Talking points For Parents
Talking with
school staff
and teachers
Talking about
cystinosis
Talking with
other children
You can help your child talk about cystinosis. Even at young ages, children can give
simple explanations to friends, teachers, and others. Every now and then, ask your
child what he or she knows about cystinosis. Then you can fill in gaps and explain
more as needed. Talking about cystinosis, in a matter-of-fact way, may help your child
feel more comfortable. And being open about it may help a child feel in control, not
worried that it’s something to hide.5
Young children may wonder why your child seems to feel sick a lot.
When you’re talking with your child’s friends, be honest but keep it simple.
For example, just say that your child needs medicines to feel better. And do
talk about all the things your child can do despite having cystinosis.5
Get to know all the people in your child’s school life. As soon as the school year begins, ask the
principal for a “point person.” That’s someone who can answer questions and handle problems.
You actually may have more than one point person (eg, a nurse for medical issues, a guidance
counselor for school-related issues).5
Ask about special education services that may be available. Children under the age of 3 years
may be eligible for Early Intervention Assessments to catch learning or growth delays early.
These may include speech/language and occupational therapy, social work or time with a
special education teacher, and so on.5
Some parents of children with cystinosis have used an Individualized Education Program or
IEP to get additional support to help with learning challenges. An IEP is a written document that
guides the education of a student with a disability. Most students between 3 and 21 years of age
who are classified with a disability according to the Individuals with Disabilities Education Act
of 2004 (IDEA) will have a current IEP. Because each IEP is designed for a single student, it is truly
individualized. It is not uncommon for a child with cystinosis to have an IEP in place.
Parents may also want to ask about a 504 Plan if there are concerns about the physical
environment in school. For example, if a child needs easier access to a bathroom or needs a
place to take medicines.
Educational programs and processes may differ from one school to the next and from state to
state. So you will want to work with your child's school to find out the types of programs that are
available and whether an IEP may be right for your child.
Learn more from the US Department of Education website at www.ED.gov.
28
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A Guide for Patients, Parents, and Caregivers
29
Just for teens
Teens Taking Charge
Stronger than cystinosis
You may have cystinosis—but cystinosis does
not have you. Making good choices every day
puts you in charge of your health. From taking
your medicine to sharing information with
others, you can shape a life that’s focused on
staying as healthy as possible. Honest, frequent
communication with family members, friends,
co-workers, school staff, advocacy groups, or
caregivers can build a network of support that
you can depend on.
30
Know Cystinosis
YOUR LIFE, YOUR HEALTH
You’ve got a lot on your plate—you’re probably busy
24/7 just with school and social activities. Add in your
medicines and appointments, and your schedule is
even more packed. But learning how to manage all
that on your own is part of becoming an adult.
A Guide for Patients, Parents, and Caregivers
31
Just for teens
TIPS TO HELP YOU TAKE CHARGE OF YOUR HEALTH
Learn more about cystinosis.
Just for teens
Decide how private you want to be.5
• You can tuck medicine and eye drops into a small sack that fits in a backpack. Or get yourself a cool
carrier—it’s your choice
• Ask your parents or doctor to explain what happens in your body with cystinosis
• At school, you can ask to take your medicines in a private room, like the school nurse’s office
• Don’t be afraid to ask questions—it’s a good way to learn how to be active in your own care
• At home, it’s a good idea to take your medicines where your parents can see. That way they don’t worry
about whether you’re missing doses
• Go to websites you can trust such as www.knowcystinosis.com
Make sure you know what your medicines are. Learn the following5:
Set up a private reminder system.5
• The name of each medicine
• Set your watch or cell phone alarm
• The dose and schedule for taking the medicine
• Send yourself a text reminder
• Why you are taking the medicine
• The possible side-effects
Always take your medicines as your doctor advises.5
• If you have new or different side-effects, let your parents or doctor know. They may be able to help you
better manage them
• Talk with your parents and doctor if you’re having trouble with any medicine. Think about how cystinosis
damages your body over time. Even if you can’t see or feel it, your medicine is helping protect your body
from more damage
Stay in touch.5
• Let your friends help. When you’re feeling bad or down, they may want to be there for you
• If health problems keep you out of school for a while, stay connected with friends. With social media,
you can keep up to date with activities and even get help with homework
• Advocacy groups are also a great source of support (see page 35)
Speak up for yourself.5
• It’s your body and your health. You have opinions, and you can share them
• It’s up to you to decide what, or how much, to tell people about your cystinosis
• It’s OK for you to talk directly with your healthcare team about your health
Source: Cystinosis Research Network
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A Guide for Patients, Parents, and Caregivers
33
Just for teens
Resources: FIND SUPPORT WHEN YOU NEED IT
Remind yourself why you are doing all this
Maybe you’re about to get your driver’s license, or you’re getting ready for the prom.
Maybe you’re hunting for the right college. Whatever your plans, doing all you can to
stay healthy may help you get there—and beyond.
Many people with cystinosis are going on to college, starting careers, or finding loving
relationships. There’s a lot to hope for and look forward to. You’ll want to be in good
shape for the big days ahead.
When you need information or want to connect with other families with cystinosis, reach out.
There are many people who have experiences to share with you. Here are some resources
you can turn to.
THE CYSTINOSIS FOUNDATION
www.cystinosisfoundation.org
(888) 631-1588
CYSTINOSIS RESEARCH FOUNDATION
www.cystinosisresearch.org
(949) 223-7610
CYSTINOSIS RESEARCH NETWORK
www.cystinosis.org
(866) 276-3669
CURE CYSTINOSIS INTERNATIONAL REGISTRY
www.cystinosis.patientcrossroads.org
For information about cystinosis, visit
www.knowcystinosis.com
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A Guide for Patients, Parents, and Caregivers
35
Learn more about cystinosis at
www.knowcystinosis.com
REFERENCES:
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JG, Schneider JA. Cystinosis. N Engl J Med. 2002;347(2):111-121. 3. About cystinosis. Cystinosis Research Foundation Web site.
http://www.natalieswish.org/About-Cystinosis. Accessed September 1, 2013. 4. Tsilou ET, Rubin BI, Reed G, et al. Nephropathic
cystinosis: posterior segment manifestations and effects of cysteamine therapy. Ophthalmology. 2006;113(6):1002-1009.
5. Cystinosis parent handbook. Cystinosis Research Network Web site. http://cystinosis.org/family-support/resources. Accessed
April 12, 2013. 6. What is a cell? Genetics Home Reference Web site. http://ghr.nlm.nih.gov/handbook/basics/cell. Accessed
October 4, 2013. 7. Cooper GM. The cell: a molecular approach. 2nd ed. National Center for Biotechnology Information (NCBI)
Bookshelf Web site. http://www.ncbi.nlm.nih.gov/books/NBK9953/. Accessed November 27, 2013. 8. Nesterova G,
Gahl WA. Gene reviews: cystinosis. National Center for Biotechnology Information (NCBI) Web site. http://www.ncbi.nlm.nih
.gov/books/NBK1400/?report=printable. Accessed September 1, 2013. 9. Gahl WA, Balog JZ, Kleta R. Nephropathic cystinosis
in adults: natural history and effects of oral cysteamine therapy. Ann Intern Med. 2007;147(4):242-250. 10. Inheriting genetic
conditions. Genetics Home Reference Web site. http://www.ghr.nlm.nih.gov/handbook/inheritance/riskassessment. Accessed
December 17, 2013. 11. Inheritance patterns. Genetics Home Reference Web site. http://www.ghr.nlm.nih.gov/handbook
/illustrations/patterns?show=recessive. Accessed December 17, 2013. 12. Kleta R, Anikster Y, Lucero C, et al. CTNS mutations
in African American patients with cystinosis. Mol Genet Metab. 2001;74(3):332-337. 13. Shotelersuk V, Larson D, Anikster Y, et
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