Hypophosphatasia (HPP) is a rare inherited disorder characterized by abnormal mineralization of bones and teeth due to deficiency of alkaline phosphatase (ALP), an enzyme that plays a key role in phosphorus and calcium metabolism. This disorder can manifest itself in various forms, from perinatal to late childhood and even adulthood, making it variable in clinical presentation and progression. Depending on the severity of the alkaline phosphatase deficiency, patients may experience a variety of symptoms, including osteopenia, increased susceptibility to fractures, and dental problems that range from temporary delayed eruption to early tooth loss.
History of the disease and interesting historical facts
Hypophosphatasia was first described in the scientific literature in 1948 by Jeffrey K. Hippel, a professor of genetics and pediatrics. The first reports of the disorder came from cases with perinatal manifestation of HPH, where pediatric isolated cases highlighted that the differences in severity of the disease can vary greatly. In 1975, a group of researchers led by Lewis highlighted the association of the genetically determined disorder with alkaline phosphatase levels, which led to further research into the molecular genetics of the disorder. Interestingly, in the 1990s, a correlation was found between HPH and certain mutations in the ALPL gene, which in itself was an important step in understanding the mechanism of the disorder.
Epidemiology
The epidemiology of hypophosphatasia indicates its extremely low prevalence, estimated at 1 in 300,000 to 500,000 live births. According to the World Health Organization, more than 300 familial cases of HFP have been reported worldwide to date, but the actual number may be significantly higher given the under-detection of the disease in mild to moderate forms. The incidence varies across geographic regions due to genetic and environmental factors.
Genetic predisposition to this disease
Hypophosphatasia is an autosomal recessive disorder caused by mutations in the ALPL gene located on chromosome 1. All mutations found in this gene result in decreased alkaline phosphatase activity, which disrupts phosphate metabolism and bone mineralization. More than 400 different mutations have been described to date, combining in stages, and they can include major rearrangements, point mutations, and deletions, demonstrating the diversity of mutations associated with this disorder.
Risk factors for the development of this disease
Known risk factors associated with hypophosphatasia include:
- Hereditary predisposition: presence of sick family members.
- Race: Higher incidences of the disease have been reported in certain ethnic groups.
- Environmental factors: exposure to toxic substances in the environment.
- Comorbidities: eg some metabolic disorders.
These factors may increase the likelihood of developing HFP.
Diagnosis of this disease
Diagnosis of hypophosphatasia includes several key steps:
Main symptoms:
- Growth retardation in children
- Frequent fractures and bone deformities
- Early tooth loss
Laboratory tests:
- Determination of the level of alkaline phosphatase in the blood (significantly below normal values).
- Other biochemical tests that can detect disturbances in phosphorus and calcium metabolism.
Radiological examinations:
- Radiography to assess bone condition and detect characteristic osteopenia.
- MRI for a more in-depth assessment of soft tissues and joints.
Other types of diagnostics:
- Genetic testing to detect mutations in the ALPL gene.
Differential diagnosis:
- Other metabolic diseases such as osteoporosis, a form of osteomalacia, and other hereditary diseases must be excluded.
Treatment
Treatment of hypophosphatasia should be multidisciplinary and individualized depending on the severity of the disease.
General treatment:
- Ensuring control over the level of phosphorus and calcium in the body.
- Support physical activity to strengthen muscles and joints.
Pharmacological treatment:
- Vitamin D and calcium supplements to compensate for mineral deficiencies.
- The use of new biological agents such as raloxifene to stimulate mineralization after their efficacy has been studied.
Surgical treatment:
- Correction of bone deformities using orthopedic interventions in cases of severe clinical picture.
Other types of treatment:
- Physiotherapy and exercise therapy to improve the general condition and functional capabilities of patients.
List of medications used to treat this disease
- Calcitriol (active form of vitamin D)
- Calcium
- Ralaxifen
- Phosphorus-containing drugs
- Phosphates
Disease monitoring
Monitoring for hypophosphatasia includes:
- Regular tests of alkaline phosphatase levels.
- Control of serum calcium and phosphorus levels.
- Evaluation of bone condition using X-rays.
The prognosis varies depending on the form and severity of the disease, but in general, early diagnosis and adequate treatment can significantly improve the quality of life of patients by preventing complications such as fractures, deformities and other related problems.
Age-related features of the disease
Hypophosphatasia can manifest itself at any age, but the characteristics of its course differ between:
- Newborns: severe forms with high mortality may be observed.
- In children: usually manifests as slow growth and frequent fractures.
- Adults: most often osteopenia and dental problems are observed, less often more acute forms of the disease.
Questions and Answers
- What is the main cause of hypophosphatasia? The underlying cause is a genetic mutation in the ALPL gene, which results in alkaline phosphatase deficiency.
- What are the most typical symptoms of the disease? The most common symptoms include growth retardation, frequent fractures, and early tooth loss.
- How is hypophosphatasia diagnosed? Diagnosis includes laboratory tests for alkaline phosphatase levels, radiography, and genetic testing.
- Is hypophosphatasia curable? Yes, treatment includes vitamins and minerals, as well as interventions to correct deformities.
- What is the prognosis for hypophosphatasia? The prognosis depends on the form of the disease, but with early diagnosis and treatment, many patients have a normal life.
In conclusion, Dr. Oleg Korzhikov emphasizes the importance of timely diagnosis and strict adherence to recommendations for the treatment of hypophosphatasia. The specialist recommends:
- Get regular check-ups and see a doctor at the first sign of illness.
- Monitor the levels of vitamins and minerals in the body.
- Maintain an active lifestyle and include physical exercise in your daily routine.
By contacting specialists, patients can significantly improve their progress and quality of life with hypophosphatasia.
