Imagine, what would happen if an amino acid called `(cystine)` (cysteine) started to accumulate inside the tiny cells in our body? That is the condition called `(Cystinosis). This is a rare, but very important genetic condition. When `(cystine)` accumulates too much inside the cells, those cells can be damaged. To be precise, this `(cystine)` causes small crystals to form inside the cells, and when they accumulate, they cause problems for various organs and tissues in our body. Let's talk about this `(Cystinosis)` in detail and simply, okay?
What is Cystinosis? Let's understand exactly!
Simply put, cystinosis is a genetic condition . What happens in this is that the amino acid `(cystine)` (cysteine) accumulates inside our cells. You know, amino acids are very important for our body. However, if this `(cystine)` is present in excess in the cells, it is harmful to the cells. Due to this excess `(cystine)` , small crystals like things form inside the cells. These crystals gradually accumulate and start damaging various organs and tissues in our body.
Cystinosis most often affects the kidneys and eyes . However, it can also damage the brain, muscles, liver, thyroid, pancreas, and in men, the testicles.
This is very rare, meaning it affects about one in a thousand people. However, it is a very serious, lifelong disease . However, if it is recognized early and treated properly, the progression and worsening of the disease can be largely controlled. However, many people eventually develop end-stage kidney disease and need a kidney transplant.
Are there different types of cystinosis?
Yes, there are three main types of cystinosis. These types are classified based on the age at which symptoms first appear (i.e. when the disease began) and the severity of the symptoms.
1. Nephropathic cystinosis (infantile type)
This is the most common type . About 95% of people with cystinosis have this type. It is also the most severe type . It is also called infantile cystinosis.
Babies with this `(Nephropathic cystinosis)` develop a special condition that damages the kidneys . It is called `(renal Fanconi syndrome)`. In this condition, the minerals and other nutrients that our body needs are not absorbed into the blood properly, but are excreted in the urine. Imagine, when a small child loses the things that his body needs in this way, the baby's growth is stunted, his bones become weak, he may become bent (this is also called `(rickets)`), and many other problems can occur.
Usually, by the age of two , cystine crystals begin to form in the cornea of a child's eyes. These crystals accumulate, and over time, the eyes become sensitive to light (photophobia). This can cause severe eye pain and discomfort . It's like the eyes turn blue when exposed to sunlight.
Children with this `(Nephropathic cystinosis)` definitely need a kidney transplant. If left untreated, the kidneys can become completely dysfunctional by the age of 10. However, if treated properly, these children can live to adulthood with a good quality of life.
2. Intermediate cystinosis (juvenile onset type)
This is also called adolescent or juvenile cystinosis. The symptoms are similar to those of infantile cystinosis, but symptoms appear in late childhood or adolescence . Symptoms may be mild or may become more severe over time.
People with this type of cystinosis will eventually need a kidney transplant. If left untreated, the kidneys can become completely dysfunctional within 15-25 years .
3. Non-nephropathic cystinosis (the type that only affects the eyes)
This is also called benign cystinosis, or ocular cystinosis. This type affects only the eyes . Cystine crystals form in the cornea of the eye, causing photophobia. However, most people with this type do not have kidney damage or other symptoms .
The age at which this condition is diagnosed (Non-nephropathic cystinosis) can vary, as symptoms are less common. However, it usually affects middle-aged adults.
Who gets cystinosis?
Cystinosis is a genetic condition that can affect anyone . The disease is inherited in an autosomal recessive pattern. This means that both parents must carry the mutated gene for the disease . If both parents are carriers of the mutated gene (meaning they have no symptoms, but have the gene), they have a 25% (one in four) chance of having a child with cystinosis.
How common is this disease?
Cystinosis is a very rare disease . Worldwide, it affects only one in 100,000 to 200,000 births.
How does cystinosis affect our body?
Cystinosis is a disease that belongs to the group of diseases called `(lysosomal storage disorder)`. Imagine, inside our cells there are small organelles called `(lysosomes)` . These are like the garbage cans of the cell. They break down nutrients like carbohydrates, proteins, and fats. Some proteins act as `(enzymes)` and help the body absorb these nutrients. Some other proteins act as `(transporters)`. That is, these transporters take the leftover `(cystine)` from those broken down things out of the lysosomes.
Now, if you lose one of those transport proteins, `(cystine)` can't get out of the lysosomes and starts accumulating inside the cells. That's when `(cystine)` forms clusters, which damage the organs.
What are the symptoms of cystinosis?
Symptoms and their severity vary depending on the age at which the disease begins and when it is diagnosed.
Symptoms of nephropathic cystinosis (infantile form) usually begin to appear between 6 and 18 months of age , when the kidneys are damaged. These are the main symptoms:
- Excessive thirst (polydipsia).
- Excessive urination (polyuria).
- Electrolyte imbalances in the body.
- Vomiting.
- Dehydration.
- Fever.
Other symptoms may include:
- Weakening of bones, rickets.
- Failure to thrive.
- Scarring or clouding of the cornea of the eyes.
- Sensitivity to light (photophobia).
- Vision impairment.
- Difficulty swallowing (dysphagia).
The symptoms of intermediate cystinosis (juvenile form) are similar to those of the infantile form. However, they begin to appear in late childhood or adolescence. Also, the symptoms may be less severe. Other symptoms that may be seen in this form include:
- Fatigue, tiredness.
- Muscle weakness .
- Muscle disease `(myopathy)` (myopathy).
- Short stature.
- Delayed puberty.
- Infertility.
Ocular cystinosis (non-nephropathic cystinosis) affects only the cornea of the eye. Photophobia is usually the only symptom . There are no kidney-related symptoms.
What are the causes of cystinosis?
This is due to genetic mutations in the gene called `(CTNS)` . This `(CTNS)` gene instructs our body to make a protein called `(cystinosin)`. `(Cystinosin)` is the transporter protein mentioned earlier. That is, its function is to take the amino acid `(cystine)` out of the lysosomes.
So, when there is a mutation in the `(CTNS)` gene, there is a defect in the `(cystinosin)` protein. Then, `(cystine)` cannot get out of the lysosomes and starts to accumulate. That's when the cysts form and damage the cells in the organs.
It has long been said that this is inherited in an ``autosomal recessive pattern''. This means that both parents must be carriers of this mutated gene (they do not have symptoms) . Only if both parents inherit this mutated gene will the child develop this disease.
How is Cystinosis diagnosed?
Your doctor will ask you about your symptoms and family medical history. He or she will then perform a physical exam and order several tests to diagnose the condition.
What tests are being done for this?
The doctor may do these tests:
- Blood test: A sample of your blood is taken and the level of cystine in the white blood cells is checked.
- Genetic testing: A geneticist will check for mutations in your (CTNS) gene.
- Urinalysis: A urine sample is taken and checked for excess minerals, nutrients, salts, and amino acids.
- Eye examination: An ophthalmologist will use a special microscope (slit lamp) to look for cystine crystals in your cornea.
If you are pregnant and someone in your family has cystinosis, and both you and your partner are found to be carriers, prenatal testing, such as amniocentesis, can be done to find out if your baby has the disease . This involves taking a sample of cells from the amniotic fluid surrounding the baby and checking for cystine levels.
Another test called ``chorionic villus sampling`` can also be used. This tests the cells in the placenta.
What are the treatments for cystinosis?
The medicine called Cysteamine
The main treatment for cystinosis is a drug called cysteamine . This is a cystine-depleting agent. This means that it reduces the levels of cystine in your cells.
If this `(cysteamine)` medicine is started early, the damage to the kidneys can be controlled and delayed to a great extent . This medicine has been able to delay the need for kidney transplantation. Some children have been able to delay kidney transplantation until adulthood. Also, this medicine improves the growth of children with the disease.
There are two types of `(Cysteamine)`: `(Cystagon™)` and `(Procysbi™)` (these are brand names). `(Cystagon™)` should be taken every six hours. `(Procysbi™)` (for those over 6 years old) has a special coating, so it can be taken every 12 hours.
The usual medicine `(cysteamine)` does not treat `(cystine)` crystals in the cornea of the eye. For this, there are two types of `(cysteamine)` eye drops approved by the US Food and Drug Administration `(FDA): `(Cystaran™)` and `(Cystadrops™)`. These drops should be applied about once an hour while you are awake. They dissolve the crystals in the cornea and reduce the sensitivity to light.
Other treatments
Children with cystinosis may need other treatments, depending on their symptoms. Treatments for Fanconi syndrome include:
- Drink plenty of water and electrolytes (to prevent excessive water loss from the body).
- Medicine to maintain the body's salt balance.
- Medicine to correct the defect in the absorption of phosphate by the kidneys.
Other treatments for cystinosis include:
- Growth hormone therapy.
- If you have insulin-dependent diabetes, you need insulin.
- Testosterone for men with hypogonadism.
- Speech and language therapy.
- Genetic counseling.
Some children who have difficulty eating may need to be fed through a tube (gastronomy tube). This tube is used to provide proper nutrition and administer medication.
Ocular cystinosis, which affects only the eyes, can also be treated in the following ways:
- Avoiding bright light.
- Wearing sunglasses.
- Keeping the eyes moist.
- Very rarely, a corneal transplant may be necessary.
Kidney transplantation
Even with early detection and treatment, people with nephropathic and intermediate cystinosis eventually develop kidney failure. Initially, your doctor may treat kidney failure with dialysis. Dialysis is a machine that takes over some of the work your kidneys do. It filters waste products from your blood and helps maintain the proper levels of certain chemicals in your body. However, kidney failure is irreversible, and eventually a kidney transplant is needed .
Kidney transplants are very successful for people with cystinosis. A donated kidney does not accumulate cystine . However, cystine can still accumulate in other organs in your body. Therefore, you will have to take medication for the rest of your life .
Are there any side effects of the treatment?
The medicine `(cysteamine)` has a slightly bad smell and an unpleasant taste . Therefore, some people may experience nausea, vomiting, and heartburn when taking this medicine. `(cysteamine)` can also cause excess stomach acid to be produced. Some people take medicines like `(proton pump inhibitors)` to reduce stomach acid. This can reduce their gastrointestinal symptoms. `(cysteamine)` can also cause bad breath `(halitosis)` and bad breath.
Can Cystinosis be prevented?
Cystinosis is a genetic condition, so it cannot be prevented . If you are pregnant or planning to become pregnant, you may want to consider genetic testing to find out if your baby is at risk of developing the disease.
What is the outlook for someone with cystinosis? / How long can they live?
At one time, nephropathic cystinosis was a fatal disease of young children. But today, with the development of the drug cysteamine and the advancement of kidney transplantation, the life expectancy of people with cystinosis has been extended into adulthood . Some people live to be over 50 years old.
Early detection of cystinosis is important. With proper treatment, the disease can be controlled. If left untreated, children with cystinosis will have kidney failure by the age of 10. Even with treatment, many children will have kidney failure in late childhood or adolescence. This will require dialysis and eventually a kidney transplant.
If you take cysteamine, you need to continue taking it for life . Research has shown that it can prevent many of the late complications of cystinosis that are not related to the kidneys.
Finally, things to remember
Cystinosis is a genetic condition that can cause a variety of symptoms. If diagnosed early and treated promptly, the progression of the disease can be largely controlled . Once fatal to young children, this disease can now be treated with medication. Even with medication, people with cystinosis eventually develop kidney failure and require a kidney transplant. However, people with the disease now live well into adulthood.
If you or someone you know has these symptoms, it's important to seek medical advice immediately . Don't panic, but it's good for everyone to be aware of these things.
` cystinosis, cystine, kidney disease, genetic disorder, Fanconi syndrome, cysteamine, kidney disease, genetic disease, child health
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