One of the groups of diseases is congenital pathology. In most cases, it is impossible to prevent them. They learn about such conditions after the birth of the baby. Genetic diseases are characterized by various manifestations. In most cases, these are defects of the internal organs and external abnormalities. One of the congenital pathologies is Waardenburg syndrome. It has characteristic features that distinguish it from other genetic defects. These include: hearing impairment, different eye color, specific appearance of patients. To diagnose this ailment, an examination with several specialists is required.
What is Waardenburg syndrome?
This disease does not belong to rare genetic defects. On average, the incidence of pathology is 1 in 4,000 newborns. Waardenburg syndrome can be suspected already at an early age, since its main manifestations are the striking unusual appearance of the baby and hearing loss. The disease was described in the middle of the twentieth century. The ophthalmologist from France, Waardenburg, discovered this genetic pathology. He studied a group of children who had features such as the Greek profile, bright eye color (in some cases, different) and deafness. In addition, the syndrome has many other manifestations, the combination of which may differ.
The disease is diagnosed in both girls and boys. The incidence of the disease is not related to gender and nationality. The risk of developing this pathology increases sharply in the presence of a genetic abnormality in one of the family members. There are currently several varieties of Waardenburg syndrome. The classification is based on genetic changes.
Reasons for the development of pathology
One of the relatively recently discovered congenital diseases is Waardenburg syndrome. The type of inheritance of this pathological condition is autosomal dominant. This implies a high risk of transmitting defective genes from parents to children. The probability of inheritance of the disease is 50%. The cause of the development of the disease are considered mutations in some genes. One of them is responsible for the formation of melanocytes - pigment cells. Mutations of this gene cause unusual eye color and heterochromia (various coloration of the iris).
Sometimes the disease is not associated with burdened heredity. In such cases, one cannot say for what reason genetic rearrangements arose. It is known that they occur during the period of fetal development. Risk factors include infectious pathologies that occur during pregnancy. Also, the cause may be stressful effects, drug intoxication, bad habits, etc.
Varieties of a pathological condition
There are 4 types of Waardenburg syndrome. They are classified by type of inheritance and the nature of genetic disorders. Most often, the first type of pathology occurs. It is characterized by a mutation of the MITF gene and PAX3 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 is observed in 20-25% of cases. Pathological genes are located on the 3rd and 8th chromosome. The first is involved in the formation of pigment cells. The second is responsible for coding factors that activate protein transcription.
In the third type of disease, a violation of the PAX3 gene occurs. 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 disease is characterized by autosomal recessive inheritance. The risk of transmission of pathology is 25%. The defective gene is located on chromosome 13. It is involved in the formation of B-endothelin protein.
Waardenburg syndrome: symptoms of the disease
Large and small criteria of pathology are distinguished. The first 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.
- Displacement of the inner eye angle. A similar phenomenon is called "TV channel."
- Bright blue coloration of the iris.
- The presence of a shred of gray hair.
- Wide nose bridge.
- Severe hearing impairment, in some cases - deafness.
- Small proportions of the middle part of the facial skull.
- A combination of these symptoms with Hirschsprung's disease. This pathology is characterized by a violation of the innervation of the intestinal tract.
Small criteria may include various symptoms. Among them: finger contractures, spinal column splitting, 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 face configuration is referred to as the “Greek profile”. Some patients experience defects such as cleft palate or cleft lip.
Diagnosis of congenital malformations
People with different eye colors are rare, but this symptom does not always indicate genetic pathology. If a similar sign is combined with hearing loss and characteristic features of the appearance, then the presence of Waardenburg syndrome is likely. To confirm the diagnosis, specialist advice is required. Inspection of an otolaryngologist, ophthalmologist, dermatologist is mandatory. It is important to find out a hereditary history. A genetic test 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 disease differs from many other hereditary pathologies.
Waardenburg Syndrome Treatment
As with other chromosomal diseases, the etiotropic treatment of Waardenburg syndrome does not exist. The actions of doctors are aimed at eliminating the symptoms of pathology. To prevent deafness, cochlear apparatus is implanted . If the pathology is combined with Hirschsprung's disease, surgery on the intestine is required. In some cases, physiotherapeutic treatment is prescribed. Sometimes plastic surgery is performed on the face.
Genetic Syndrome Prevention
The probability 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 performed. It is necessary in case of burdened heredity.
If a similar disease was not observed among relatives, it is impossible to prevent the development of pathology. To prevent genetic disorders, it is recommended to avoid stress and other factors with teratogenic effects. The prognosis for life with this pathology is favorable.