Pendred syndrome

Pendred syndrome is a hereditary disorder that is caused by dysfunction of the thyroid gland and associated hearing loss. This syndrome, which belongs to a group of syndromic disorders, is characterized by auriculo-thyroid and/or conductive hearing loss, as well as enlargement of the thyroid gland (goiter). Pendred syndrome has an autosomal recessive pattern of inheritance, which means that both parents must be carriers of the mutant alleles for the disease to manifest in offspring. Clinical manifestations are varied and can include both ear, nose and throat symptoms and endocrine disorders. The syndrome is often diagnosed in children and adolescents, which emphasizes the need for early detection and treatment in order to correct the hearing and general congenital condition of the patient.

History of the disease and interesting historical facts

Pendred syndrome was first described in the early 20th century. In 1956, Dr. D. Pendred detailed the main clinical manifestations of the syndrome, which made it possible to establish its relationship with iodine deficiency and changes in thyroid function. Scientists began to notice that some patients with hearing loss had enlarged thyroid glands, which in practice contributed to the understanding of this pathology. Over the years, research was conducted to study the genetic and molecular basis of the syndrome, and in 1997, the SLC26A4 gene responsible for its development was identified. Interestingly, the landmark of Pendred syndrome is its association with some forms of destructive thyroid disease and hearing abnormalities, which provides additional research in the field of genetics and endocrinology.

Epidemiology

Pendred syndrome is considered a rare disorder. Its prevalence is estimated to be approximately 1 in 7,500–10,000 live births. However, most cases may remain undiagnosed or misinterpreted given the variety of clinical manifestations. Regions with low iodine levels in the diet have a higher incidence, which is associated with a lack of essential micronutrients to maintain normal thyroid function. According to some studies, the frequency of the SLC26A4 gene associated with Pendred syndrome may be as high as 2% in populations of countries with low iodine intake. Thus, this syndrome highlights the importance of health monitoring, especially in risk groups.

Genetic predisposition to this disease

Pendred syndrome is an inherited disorder that is transmitted in an autosomal recessive manner. The main gene associated with this syndrome is called SLC26A4, which codes for a protein involved in cellular anion exchange. Mutations in this gene result in dysfunction of the oral carrier responsible for regulating ion levels and fluid exchange in the inner ear and thyroid gland. More than 100 different mutations in the SLC26A4 gene have been described in the literature, with the most common being the IVS7-2A>G and p.Tyr744Cys mutations. Studies show that 50-80% patients with thyroid insufficiency have double or triple copies of this gene. Genetic testing may be useful to confirm the diagnosis and analyze the risk of transmitting the disease to future generations.

Risk factors for the development of this disease

There are several risk factors that contribute to the development of Pendred syndrome. These include:

• Heredity: a family history of hearing loss or thyroid disease.
• Ethnicity: The syndrome is more common in certain ethnic groups, particularly Iranian and Caucasian peoples.
• Dietary iodine deficiency: Iodine deficiency is considered an important factor in the development of thyroid disease and associated hearing loss.
• Environmental factors: potential exposure to chemicals and pollutants that may affect thyroid function.

These factors can both enhance the impact and increase the likelihood of developing the disease in predisposed individuals.

Diagnosis of this disease

Diagnosis of Pendred syndrome is based on a comprehensive approach that includes clinical examination, genetic testing, and specialized genealogical studies.

• Main symptoms: Hearing loss, enlarged thyroid gland, increased susceptibility to ear and respiratory infections. Patients may also have other endocrine disorders.
• Laboratory tests: Complete blood count, thyroid hormone levels, antibody test.
• Radiological examinations: Ultrasound of the thyroid gland and CT of the temporal bones to assess structural changes.
• Other types of diagnostics: Auditory audiometry is performed to determine the degree of hearing loss.
• Differential diagnosis: Other causes of hearing loss and thyroid disease, including persistent forms of otosclerosis or other genetic syndromes, must be excluded.

As a result of a comprehensive analysis of the examination data, a final diagnosis can be made and appropriate treatment can be started.

Treatment

Treatment of Pendred syndrome involves a comprehensive approach aimed at correcting hearing and normalizing thyroid function.

• General treatment: Measures to improve hearing (eg, using hearing aids or cochlear implantation).
• Pharmacological treatment: Thyroid hormone replacement therapy in case of hypothyroidism.
• Surgical treatment: In some cases, removal of the enlarged thyroid gland may be necessary.
• Other types of treatment: Speech therapy and audiology to improve speech and musical skills can be effective in rehabilitation.

Thus, timely and comprehensive treatment can significantly improve the quality of life of patients with Pendred syndrome.

List of medications used to treat this disease

Medicines used to treat Pendred syndrome include:

• Levothyroxine sodium (replacement therapy for hypothyroidism).
• Medications that improve hearing, such as hearing aids.
• Medicines to treat ear infections (antibiotics if needed).
• Vitamin and mineral complexes to improve overall health.

It is important that therapy is carried out under the supervision of a specialist and tailored to the individual needs of the patient.

Disease monitoring

Monitoring of patients with Pendred syndrome includes regular follow-up examinations to assess changes in hearing and thyroid function. The following follow-up visits are recommended:

• Regular determination of thyroid hormone levels every 3-6 months.
• Audiometric tests every 6-12 months to assess hearing dynamics.
• Ultrasound examination of the thyroid gland to monitor the size and structure of the thyroid gland.

The prognosis for Pendred syndrome with early diagnosis and timely treatment is generally positive, but complications such as progressive hearing loss or thyroid dysfunction may occur. It is important to continue monitoring to identify and correct problems in a timely manner.

Age-related features of the disease

Pendred syndrome can manifest itself in different age groups with different degrees of severity. In newborns and children, severe hearing loss and enlarged thyroid glands are most often detected. In adolescents, symptoms may be less pronounced, but it is important to consider the possibility of disease progression. In people over 50, deterioration of the general condition and an increased risk of complications, such as cancerous transformation of the thyroid gland, may be observed, which requires a careful approach to diagnosis and treatment in elderly patients.

Questions and Answers

• What is Pendred syndrome? Pendred syndrome is an inherited disorder associated with thyroid dysfunction and hearing loss. It is characterized by an enlarged thyroid gland and hearing loss.
• What are the symptoms of Pendred syndrome? The main symptoms include hearing loss, enlargement of the thyroid gland, and an increased susceptibility to ear infections.
• How is Pendred syndrome diagnosed? Diagnosis includes clinical examination, genetic testing, hearing tests, and thyroid ultrasound.
• What is the treatment for Pendred syndrome? Treatment includes thyroid hormone replacement therapy, hearing aids, and in some cases surgery.
• What is the prognosis for patients with Pendred syndrome? The prognosis is generally positive with early diagnosis and treatment, although complications may occur that require further monitoring.