One of the groups of diseases are congenital pathologies. In most cases, it is impossible to prevent them. Such conditions are known after the birth of the baby. Genetic diseases are characterized by various manifestations. In most cases, these are defects of internal organs and external anomalies. One of the congenital pathologies is the Waardenburg syndrome. It has characteristic features that distinguish it from other genetic defects. These include: hearing loss, different eye color, specific appearance of patients. To diagnose this disease, examination by several specialists is required.
What is Waardenburg syndrome?
This disease is not a rare genetic defect. On average, the incidence of pathology is 1 in 4000 newborns. Waardenburg syndrome can be suspected already at an early age, since its main manifestations are conspicuous unusual appearance of the baby and hearing loss. The disease was described in the middle of the twentieth century. This genetic pathology was discovered by an ophthalmologist from France Waardenburg. He studied a group of children who exhibited features such as a Greek profile, bright eye color (various in some cases), and deafness. In addition, the syndrome has many other manifestations, the combination of which may vary.
The disease is diagnosed in both girls and boys. The frequency of occurrence of the disease is not related to gender and nationality. The risk of developing this pathology increases sharply in the presence of a genetic anomaly in one of the family members. Currently, there are several varieties of Waardenburg syndrome. The classification is based on genetic changes.
Causes for the development of pathology
One of the relatively recently discovered congenital diseases is Waardenburg's syndrome. The mode of inheritance of this pathological condition is autosomal dominant. This implies a high risk of passing defective genes from parents to children. The probability of inheriting the disease is 50%. Mutations in certain genes are considered to be the cause of the development of the disease. One of them is responsible for the formation of melanocytes - pigment cells. Mutations in this gene cause unusual eye color and heterochromia (different coloration of the irises).
Sometimes the disease is not associated with aggravated heredity. In such cases, it is impossible to say for what reason the genetic rearrangements occurred. It is known that they occur during fetal development. Risk factors include infectiouspathologies that occur during pregnancy. It can also be caused by stress, drug intoxication, bad habits, etc.
Varieties of the pathological condition
There are 4 types of Waardenburg syndrome. They are classified according to the type of inheritance and the nature of genetic disorders. The first type of pathology is the most common. It is characterized by a mutation of the MITF and PAX3 gene located on the second chromosome. The type of inheritance is autosomal dominant. The PAX3 gene is responsible for the production of a transcription factor, which in turn controls the migration of neural crest cells.
The second type of Waardenburg syndrome occurs in 20-25% of cases. Pathological genes are located on chromosomes 3 and 8. The first is involved in the formation of pigment cells. The second is responsible for encoding factors that activate protein transcription.
In the third type of disease, there is a violation of the PAX3 gene. This type of pathology is characterized by the severity of the course. Unlike the first type, the mutating gene is not in a hetero-, but in a homozygous state. Sometimes nonsense mutations are noted.
The fourth type of the disease is characterized by autosomal recessive inheritance. The risk of pathology transmission is 25%. The defective gene is located on chromosome 13. It is involved in the formation of the B-endothelin protein.
Waardenburg syndrome: symptoms of the disease
There are major and minor pathology criteria. The former are found in most cases. These include:
- Heterochromia. People with different eye colors make up about 1% of the total population of the Earth. Heterochromia is not always associated with a pathological syndrome.
- Offset of the inner eye corner. This phenomenon is called "television".
- Bright blue coloration of the iris.
- Having a tuft of gray hair.
- Broad nose bridge.
- Severe hearing loss, in some cases deafness.
- Small proportions of the middle part of the facial skull.
- The combination of these symptoms with Hirschsprung's disease. This pathology is characterized by a violation of the innervation of the intestinal area.
Minor criteria may include various symptoms. Among them: contractures of the fingers, splitting of the spinal column, syndactyly, skin changes (the presence of a large number of moles, leukoderma). Often there is hypoplasia of the wings of the nose and a decrease in the superciliary arches. This facial configuration is referred to as the "Greek profile". Some patients have defects such as cleft palate or cleft lip.
Diagnosing a congenital anomaly
People with different eye colors are rare, but this symptom does not always indicate a genetic pathology. If a similar symptom is combined with hearing loss and characteristic features of appearance, then the presence of Waardenburg syndrome is likely. To confirm the diagnosis, consultations of specialists are required. Obligatory examination by an otolaryngologist, ophthalmologist, dermatologist. Importantfind out hereditary history. Genetic testing is performed to confirm the diagnosis. After it, it is established whether there is Waardenburg syndrome. The level of intelligence in patients is normal. This distinguishes this disease from many other hereditary pathologies.
Treatment of Waardenburg syndrome
As with other chromosomal diseases, there is no etiotropic treatment for Waardenburg syndrome. The actions of doctors are aimed at eliminating the symptoms of pathology. To prevent deafness, a cochlear device is implanted. If the pathology is combined with Hirschsprung's disease, surgical intervention on the intestine is required. In some cases, physiotherapy is prescribed. Sometimes facial plastic surgery is performed.
Prevention of genetic syndrome
The likelihood that Waardenburg syndrome will develop in a child with a disease of one of the parents is very high. Therefore, during pregnancy, a genetic study of the fetus is carried out. It is necessary in case of burdened heredity.
If such a disease was not observed in relatives, it is impossible to prevent the development of pathology. To prevent genetic disorders, it is recommended to avoid stress and other factors that have a teratogenic effect. The prognosis for life with this pathology is favorable.
