Osteopetrosis
Osteopetrosis is a bone density disorder, so it breaks easily. This condition is triggered by impaired function of osteoclasts, a type of bone cell. Under normal circumstances, osteoclasts function to break down old bone tissue when new bone tissue develops. In patients with osteopetrosis, osteoclasts do not damage bone tissue, which causes abnormal bone growth.
Osteopetrosis is a disorder due to hereditary factors, so it cannot be prevented. Routine screening for genetic disorders before delivery, followed by appropriate treatment and therapy, can help osteopetrosis sufferers to live a normal life.
Symptoms of Osteopetrosis
The experts divide osteopetrosis into several types, each of which has various symptoms, namely:
Autosomal dominant osteopetrosis (ADO).
ADO is mild osteopetrosis, which usually attacks people aged 20-40 years. ADO is the most common type of osteopetrosis, and is estimated to occur in 1 in 20 thousand people.
People with osteopetrosis have a 50% lower risk for children. One gene mutation from just one parent is enough to trigger ADO in a person.
In some cases, ADO does not cause symptoms. But in some patients, ADO can cause a number of symptoms such as headaches, bone fractures in many places, bone infections (osteomyelitis), degenerative arthritis (osteoarthritis), and scoliosis or abnormal conditions in the spine.
Autosomal recessive osteopetrosis (ARO).
ARO is a type of severe osteopetrosis, which can affect the baby even though the baby is still in the womb. Infants suffering from ARO have very fragile bone conditions. Even during labor, a baby's shoulder bone can be broken.
Until the age of one year, babies with ARO show symptoms of anemia and thrombocytopenia (platelet blood cell deficiency). Other symptoms that can appear include facial muscle paralysis, hypocalcemia (low calcium levels), hearing loss, recurring infections, slow growth, short posture, abnormal teeth, and enlarged liver and spleen. In more severe cases, ARO sufferers can experience brain abnormalities, mental retardation, and frequent seizures.
A person can suffer from ARO if inherited from mutated genes from each parent. However, parents who carry the gene may not suffer from this disease.
ARO is classified as rare, and only occurs in 1 in 250 thousand people. However, this condition is very dangerous. If left untreated, the average child with ARO lives less than 10 years.
Intermediate autosomal osteopetrosis (IAO).
IAO is a type of osteopetrosis that can be inherited from one or both parents. This type of osteopetrosis is also quite rare.
Although IAO is not as life-threatening as ARO, but IAO can trigger calcium buildup in the brain. This condition can cause people with IAO to experience mental retardation.
X-linked osteopetrosis.
This type of osteopetrosis is inherited through the X chromosome. Symptoms that appear in this type of osteopetrosis are disorders of the immune system that can cause the development of more severe infections, as well as lymphedema. Another symptom of X-linked osteopetrosis is anhidrotic ectodermal dysplasia, a skin disease characterized by a lack of hair on the head and body, and a lack of the body's ability to produce sweat.
Causes of Osteopetrosis
Osteopetrosis is caused by mutations or changes in one of the genes involved in the development and function of osteoclasts, cells that play a role in the process of breaking bones.
Each type of osteopetrosis is caused by different gene mutations, as explained as follows:
Diagnosis of Osteopetrosis
The diagnosis of osteopetrosis can be obtained through imaging tests, such as X-ray examination. X-ray examination will help the doctor to see if there are infections or cracks in the bone. Other imaging tests, such as CT scans or MRIs, can also be performed as investigations.
For patients with severe osteopetrosis, blood samples will be taken to be tested in the laboratory. Under these conditions, calcium levels in the blood will be low, and levels of acid phosphatase and the hormone calcitriol will increase.
Osteopetrosis treatment
Osteopetrosis in adult patients does not need to be treated, unless it has caused complications. In these conditions, the doctor will treat bone cracks, or perform joint replacement procedures.
In contrast, osteopetrosis in infants must be treated immediately. Some methods for treating babies with osteopetrosis include:
Osteopetrosis complications
A number of complications that can be experienced by sufferers of osteopetrosis, among others are the failure of bone marrow function accompanied by severe anemia, bleeding, and infection. In addition, osteopetrosis sufferers can also experience obstacles in the process of growth and development.
Symptoms of Osteopetrosis
The experts divide osteopetrosis into several types, each of which has various symptoms, namely:
Autosomal dominant osteopetrosis (ADO).
ADO is mild osteopetrosis, which usually attacks people aged 20-40 years. ADO is the most common type of osteopetrosis, and is estimated to occur in 1 in 20 thousand people.
People with osteopetrosis have a 50% lower risk for children. One gene mutation from just one parent is enough to trigger ADO in a person.
In some cases, ADO does not cause symptoms. But in some patients, ADO can cause a number of symptoms such as headaches, bone fractures in many places, bone infections (osteomyelitis), degenerative arthritis (osteoarthritis), and scoliosis or abnormal conditions in the spine.
Autosomal recessive osteopetrosis (ARO).
ARO is a type of severe osteopetrosis, which can affect the baby even though the baby is still in the womb. Infants suffering from ARO have very fragile bone conditions. Even during labor, a baby's shoulder bone can be broken.
Until the age of one year, babies with ARO show symptoms of anemia and thrombocytopenia (platelet blood cell deficiency). Other symptoms that can appear include facial muscle paralysis, hypocalcemia (low calcium levels), hearing loss, recurring infections, slow growth, short posture, abnormal teeth, and enlarged liver and spleen. In more severe cases, ARO sufferers can experience brain abnormalities, mental retardation, and frequent seizures.
A person can suffer from ARO if inherited from mutated genes from each parent. However, parents who carry the gene may not suffer from this disease.
ARO is classified as rare, and only occurs in 1 in 250 thousand people. However, this condition is very dangerous. If left untreated, the average child with ARO lives less than 10 years.
Intermediate autosomal osteopetrosis (IAO).
IAO is a type of osteopetrosis that can be inherited from one or both parents. This type of osteopetrosis is also quite rare.
Although IAO is not as life-threatening as ARO, but IAO can trigger calcium buildup in the brain. This condition can cause people with IAO to experience mental retardation.
X-linked osteopetrosis.
This type of osteopetrosis is inherited through the X chromosome. Symptoms that appear in this type of osteopetrosis are disorders of the immune system that can cause the development of more severe infections, as well as lymphedema. Another symptom of X-linked osteopetrosis is anhidrotic ectodermal dysplasia, a skin disease characterized by a lack of hair on the head and body, and a lack of the body's ability to produce sweat.
Causes of Osteopetrosis
Osteopetrosis is caused by mutations or changes in one of the genes involved in the development and function of osteoclasts, cells that play a role in the process of breaking bones.
Each type of osteopetrosis is caused by different gene mutations, as explained as follows:
- CLCN7 gene mutations are known to be the cause of most autosomal dominant osteopetrosis, 10-15% of cases of autosomal recessive osteopetrosis, and a number of cases of intermediate autosomal osteopetrosis.
- 50% of autosomal recessive cases are caused by TCIRG1 gene mutations.
- X-linked osteopetrosis is caused by a mutation of the IKBKG gene. This gene is located on the X chromosome. Chromosomes are parts of cells that contain genetic information, one of which functions to regulate gender. In men who have one X chromosome, mutations in just one copy of a gene in each cell, will trigger this disorder. Whereas in women, who have two X chromosomes, mutations must occur in the two copies of the gene. Therefore, X-linked osteopetrosis generally occurs in men.
- In 30% of osteopetrosis cases, it is not known what causes it.
Diagnosis of Osteopetrosis
The diagnosis of osteopetrosis can be obtained through imaging tests, such as X-ray examination. X-ray examination will help the doctor to see if there are infections or cracks in the bone. Other imaging tests, such as CT scans or MRIs, can also be performed as investigations.
For patients with severe osteopetrosis, blood samples will be taken to be tested in the laboratory. Under these conditions, calcium levels in the blood will be low, and levels of acid phosphatase and the hormone calcitriol will increase.
Osteopetrosis treatment
Osteopetrosis in adult patients does not need to be treated, unless it has caused complications. In these conditions, the doctor will treat bone cracks, or perform joint replacement procedures.
In contrast, osteopetrosis in infants must be treated immediately. Some methods for treating babies with osteopetrosis include:
- Provision of vitamin D in order to stimulate osteoclast cells, so that the process of breaking bones can run normally.
- Calcitriol administration is accompanied by a limitation of calcium intake.
- Erythropoietin hormone therapy to overcome anemia.
- Giving corticosteroids to stimulate bone breakdown and treat anemia. This method may need to be done for several months or several years, and is not the first choice method for treating osteopetrosis.
- Surgery to treat bone fractures.
- Bone marrow transplantation, to cure bone marrow disease and metabolic disorders. Although quite risky, but the benefits derived from this method outweigh the risks.
Osteopetrosis complications
A number of complications that can be experienced by sufferers of osteopetrosis, among others are the failure of bone marrow function accompanied by severe anemia, bleeding, and infection. In addition, osteopetrosis sufferers can also experience obstacles in the process of growth and development.
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