Osteopetrosis diagnosisDiagnosis of osteopetrosis includes detailed and correct clinical assessment methods such as:-
- Blood test:- The severe forms of osteopetrosis occur with severe anemia. A decrease in the number of erythrocytes and hemoglobin indicates the suppression of bone marrow function.
- Biochemical research:- The presence of an autosomal dominant type of disease may indicate an increase in creatine kinase and tartrate-resistant alkaline phosphatase. This study is necessary for severe changes in the bone tissue composition that is undetected during radiography.
- Molecular genetic research:- The method of direct DNA sequencing helps confirm the presence of osteopetrosis and its type. It accurately detects mutation in a particular gene.
- Radiography:- The simplest, easiest to carry out, inexpensive, and sufficiently informative method is the X-ray examination. It helps detect the disease characteristic signs such as compact bone tissue, narrowed Haversian canals, and metaphyses (portions of long bones) injury.
- Bone biopsy:- Specialist takes a piece of bone to examine the number of osteoclasts, their structure, and properties. It is useful in determining the type of osteopetrosis.
- Computed and magnetic resonance imaging:- Modern diagnostic methods such as CT scan and MRI assist in determining changes in the bone tissue structure. It also detects bone sclerosis and bone marrow edema.
Osteopetrosis treatmentThere is no specific treatment for the disease. Distinctive therapy helps to combat the symptoms and their complications. Bone marrow transplant:- In most cases, the only method that guarantees high efficiency in treating osteopetrosis is bone marrow transplantation. It includes the replacement of one’s osteoclasts with donor ones. In a child, post-transplantation, the growth and development of the body normalize. Also, a sign of neurological disorder decreases, vision and hearing improve, but complete recovery does not occur. The other therapeutic techniques are supportive and symptomatic. The use of antianemic drugs, vitamin D, physiotherapy exercises, and gymnastics are different techniques that assist in treating the disease. Osteopetrosis is a hereditary disease that can lead to death, especially in children. In children with osteopetrosis, regular examination & preventive treatment is necessary. It is essential to alleviate the symptoms with a proper treatment regimen to improve the quality of life.
Osteopetrosis is characterized by excessive bone density throughout the body. Common symptoms include fractures, low blood cell production, and cranial nerve dysfunction, causing blindness, deafness, and facial nerve palsy. Patients may have frequent infections of the teeth and jawbones.
Symptoms by types:
Autosomal recessive- Malignant infantile osteopetrosis
Malignant infantile is the most severe type of osteopetrosis that occurs from birth and, if left untreated, can lead to death within the first ten years of life. Symptoms vary depending on the exact change in the gene (mutation).
- Overly large head (macrocephaly)
- Hydrocephalus -accumulation of cerebrospinal fluid (CSF)
- Abnormal growth of the cerebral spaces in the brain (ventricles)
- Retinal atrophy
- Wide-set eyes (hypertelorism)
- Bulging of the eyeball forward (exophthalmos)
- Involuntary rhythmic eye movements (nystagmus)
- Hearing loss
- Abnormally small jaw (micrognathia)
- Inflammation and irritation of the nasal mucous membrane (rhinitis)
- Difficulty in eating and growth retardation
- Liver and spleen swelling (hepatosplenomegaly)
- Abnormal hardening of some bones (osteosclerosis)
- Ribs and long bones fractures
- Lumbar vertebrae inflammation (osteomyelitis)
- Increased density of the bones (hyperostosis of the skull), leading to compression of the nerves
- Increased pressure inside the skull
- Severe neurodegeneration symptoms in infants, which is a rare condition
- Reduced space of the bone marrow
- Severe deficiency of all types of blood cells (pancytopenia)
Autosomal dominant- Adult osteopetrosis
Autosomal dominant osteopetrosis usually occurs in late childhood or adulthood. It is hard to diagnose this form of disease since it causes symptoms rarely. Common symptoms are:
- osteomyelitis (especially of the jaw)
- Hyperostosis of the skull.
- Pus-filled sacs in the tissues around the teeth (dental abscess)
- Rhinitis, hepatosplenomegaly, anemia, and extramedullary hematopoiesis
Intermediate autosomal recessive
The intermediate type usually occurs in children and can be inherited as an autosomal recessive or autosomal dominant trait. The severity of the disease varies. Symptoms may include:
- Abnormal hardening of some bones
- Osteomyelitis, especially of the lower jaw
- Abnormally close knees
- Abnormally wide ankles
- Hyperostosis of the skull
- Optic atrophy
- Loss of vision
- Muscle weakness and rhinitis
- Mandibular prognathism
- Dental abnormalities
- Milk retention
- Deformity of the crown of the tooth
- Dental caries
- Paralysis of the facial nerve
- Decreased platelet counts
X-linked recessive osteopetrosis
X-linked osteopetrosis is very rare, but conditions are severe. In addition to the common signs with osteopetrosis, it shows the following symptoms:-
- Fluid retention and localized tissue edema (lymphedema)
- Abnormalities in the hair, skin, nails, and sweat glands (ectodermal dysplasia)
The primary cause of osteopetrosis is the impaired functioning of osteoclasts. Osteoclasts are a multinucleated bone cell that breaks down bone tissue and responsible for changing the bone structure by maintaining, repairing, and remodeling.
Change in a DNA sequence (mutations) causes osteopetrosis of different conditions like:-
- The most common autosomal dominant condition is caused by a mutation in the CLCN7 gene located on chromosome 16. It encodes one of the subunits of chloride-selective ion channels located on the surface of osteoclast cells.
- It forms hydrochloric acid, which is necessary for the breakdown of calcium salts that make up the bone tissue.
- The CLCN7 gene defect causes structural changes in ion channels and reduces the release of hydrochloric acid to a great extent, which is the cause of osteopetrosis.
- Change in the DNA sequence of the CLCN7 gene causes 10-15% of cases of autosomal recessive osteopetrosis.
- The most severe type of osteopetrosis- autosomal recessive is a more genetically heterogeneous condition possibly caused by multiple gene mutations.
- According to modern genetics, about 50% of autosomal recessive osteopetrosis is caused by mutations in the TCIRG1 gene on the 11th chromosome.
- A fault in the IKBKG gene (mutations) causes X-linked osteopetrosis.
How rare is osteopetrosis?
In the general population, 1 in 250,000 people is born with malignant infantile osteopetrosis. Adult osteopetrosis affects about 1 in 20,000 people, and men and women equally suffer. The X-linked osteopetrosis affects mainly men due to the way the mutation is inherited.
What are the complications of osteopetrosis?
The main complication of osteoporosis are:-
- The injuries to the musculoskeletal system
- Physical developmental delays
- Postural syndrome – hump in the thoracic region (hunchback)
- Can cause gastrointestinal (GI) symptoms because of poor posture
How to prevent osteopetrosis?
Since osteopetrosis is a genetic disease, there are no preventive measures for it. If there have been cases of mutation associated with bone tissue in the family, the doctor recommends consulting a medical geneticist during pregnancy planning or undergoing comprehensive prenatal diagnostics.
What are the different types of osteopetrosis?
There are four types of osteopetrosis:-
- Autosomal recessive- Malignant infantile osteopetrosis
- Autosomal dominant- Adult osteopetrosis
- Intermediate autosomal recessive
- X-linked recessive osteopetrosis
What is the differential diagnosis for osteopetrosis?
Symptoms of the following conditions may be similar to those of osteopetrosis. Differentiating signs and symptoms help at an accurate diagnosis of the disease.
- Melorheostosis- irregular growth of new bone tissue
- Osteopoikilosis- the presence of multiple sclerotic lesions of the spongy bones
- Osteogenesis imperfecta- a genetic disorder that causes the imperfect bone formation