In the modern world, almost all parents knowabout such a disease as rickets. Every child's doctor warns about the need to prevent this pathology from the first months of the baby's life. Rickets refers to acquired diseases that develop due to the deficiency of cholecalciferol - a substance known as vitamin D.
However, in some cases, children of the earlyage there are symptoms of pathology, despite the observance of preventive measures. In such a case, one should suspect a disease such as phosphate-diabetes. Unlike rickets, this ailment belongs to genetic pathologies. Therefore, it is a more serious disease and requires a long-term comprehensive treatment.
What is phosphate-diabetes?
This is the name of a group of genetic diseases,associated with a violation of mineral metabolism. In another way pathology is called vitamin D-resistant rickets. Dominant type of phosphate-diabetes is found in about 1 child from 20 thousand newborn babies. For the first time the disease was described in 1937. Later it became clear that there are other genetic forms of pathology. Most often, phosphate-diabetes is detected in early childhood. Attention of parents is attracted by gait disturbance and bending of bones.
Some forms of pathology are accompanied by othermetabolic disorders. Sometimes the disease is asymptomatic, and it can be identified only by laboratory analysis. The disease is classified with acquired rickets, hypoparathyroidism and other endocrine pathologies. Treatment should be comprehensive from an early age.
Causes of the disease
The main cause of development of phosphate-diabetesis a violation in the genetic structure. Mutations are inherited. Carriers of pathological gene can be both women and men. Mutation occurs in the X-linked chromosome, which is dominant. In rare cases, phosphate-related diabetes can be acquired. It develops against the background of tumors of mesenchymal tissue, which are formed during the intrauterine period. In this pathology is called "oncogenic rickets."
The disease belongs to the group of tubulopathies -disturbances in kidney function. Due to the fact that the reabsorption of minerals in the proximal tubules decreases, a deficiency of phosphorus in the body develops. In addition, the intestinal absorption capacity is impaired. As a result, changes in the mineral composition of bone tissue are observed. Often there is a violation of osteoblast function. Men transmit the pathologically changed gene only to daughters, and women - to children of both sexes. As a rule, in boys, the disease is more severe than that of girls.
Classification of phosphate-diabetes in children
There are several forms of the disease that differamong themselves by genetic and clinical criteria. Most often, X-linked hypophosphatemic rickets are diagnosed, which has a dominant type of inheritance. Nevertheless, there are other varieties of pathology. Classification includes the following forms of the disease:
- X-linked dominant type of phosphate-diabetes. It is characterized by changes in the PHEX gene, which encodes endopeptidase. This enzyme is responsible for the transport of various minerals through the ion channels of the kidneys and small intestine. Due to mutation of the gene, this process slows down, which causes the deficiency of phosphate ions in the body.
- X-linked recessive type. Characterized by a mutation of the CLCN5 gene, which encodes a protein responsible for the operation of the chloride ion channels. As a result of the defect, the transport of all substances through the membrane of the renal tubules is disrupted. Carriers of this type of pathology can be both women and men. However, the disease develops only in boys.
- Autosomal dominant type of phosphate-diabetes. It is associated with a genetic mutation in chromosome 12. Due to a defect, osteoblasts produce a pathological protein that promotes increased excretion of phosphates from the body. Pathology is characterized by a relatively easy flow, in contrast to X-linked forms.
- Autosomal recessive type. It is rare. Characterized by a defect in the DMP1 gene located in the 4 chromosome. It encodes a protein responsible for the development of bone tissue and dentin.
- Autosomal recessive type, accompanied by the release of calcium in the urine. It occurs due to a defect in the gene located in the 9 chromosome and is responsible for the operation of sodium-dependent renal channels.
In addition to these forms of phosphate-diabetes, there are other types of pathology. Some varieties of the disease have not been studied so far.
Differences between rickets and phosphate-diabetes
Rickets and phosphate-diabetes in children are not exactlythe same, although the clinical picture of the diseases is almost identical. Differences between these pathologies in the etiology and mechanism of development. Ordinary rickets is an acquired ailment associated with a deficiency of cholecalciferol. This substance is formed in the skin under the influence of sunlight. The diagnostic dose of vitamin D is taken daily for all children from 1 month to 3 years, excluding the summer period. Due to the lack of cholecalciferol, the process of calcium assimilation is disrupted. As a result, deformation of bones develops.
The difference between phosphate-diabetes is that itrefers to congenital diseases. With this pathology, absorption of mineral substances in the kidneys, in particular - phosphates, is impaired. In some cases, calcium deficiency is also noted. Due to the violation of the mineral composition of bone tissue, the symptoms of pathologies are similar. The difference between them can only be established after laboratory diagnosis.
Hypophosphatemic rickets in infants: symptoms of the disease
Symptoms of the disease are usually diagnosed on the secondyear of life. In rare cases, hypophosphatemic rickets are observed in infants. Symptoms that can be diagnosed in infancy are muscle hypotension and limb shortening. The main clinical manifestations are:
- Deformation of the joints of the legs.
- O-shaped curvature of the lower extremities.
- The growth retardation in children - becomes noticeable after 1 year.
- Thickening of wrist joints and costal cartilage - "rachitic bracelets and rosary."
- Pain in the pelvic bones and spine.
- Damage to tooth enamel.
Most often, the main complaint of the parents is that the baby's legs are twisted. When the disease progresses, softening of the bones occurs - osteomalacia.
Diagnosis of phosphate-diabetes and rickets
To identify pathology, a study is conductedbiochemical composition of blood. In this case, hypophosphatemia is noted. The level of calcium is normal in most cases, sometimes it is reduced. In the midst of rickets, alkaline phosphatase increased. When radiography reveals osteoporosis and violation of bone growth zones. In the urine there is a large amount of phosphate. Sometimes there is calcium.
Treatment of rickets and phosphate-diabetes
For the treatment of phosphate-diabetes, largedoses of cholecalciferol. In some cases, calcium preparations are indicated. Be sure to consume medicines containing phosphorus. To improve the condition, vitamin and mineral complexes are prescribed. These include preparations "Vitrum", "Duovit", "Alphabet", etc.
At the expressed bends of bones it is shown physiotherapeutic treatment, exercise therapy and operative intervention. Consultation of an orthopedic physician is necessary.
Preventive measures and prognosis
Prevention measures include pediatrician examinations andsurgeon, walk in the fresh air, the appointment of vitamin D from the first month of life. If the family has patients with phosphate-diabetes, genetic research should be carried out during fetal development. The prognosis is most often favorable with timely treatment.