Introduction

Turner syndrome (TS) is a congenital disorder that affects people assigned female at birth (AFAB), and is caused by partial or total loss of an X chromosome. People AFAB with Turner syndrome have delayed sexual maturation, small stature, are primarily sterile, and exhibit skin webbing in the neck area. In addition to these, a person with Turner Syndrome may also have problems such as heart issues, hearing loss, and visual loss.

Turner syndrome patients frequently experience hearing loss; it is estimated that 50-90% of Turner syndrome sufferers will experience hearing impairment at some point in their lives.

Hearing loss can greatly impact academic achievement, social interactions, and communication abilities. In order to minimise these consequences and guarantee improved social and academic results, early intervention is essential.¹

A detailed look

In the majority of cases, Turner syndrome is not inherited from the parents. When monosomy X is the source of this disorder, the chromosomal aberration develops randomly in the parent cell during the development of reproductive cells (eggs and sperm). Reproductive cells with an incorrect number of chromosomes can arise from a cell division defect known as nondisjunction.

Mosaic Turner syndrome is also not hereditary. It happens at random during cell division in the early stages of embryonic development in an affected individual. As a result, some of the cells in the affected individual have two X chromosomes, whereas other cells only have one copy of the X chromosome. Other sex chromosome abnormalities can also be present in individuals with X chromosomal mosaicism.

People AFAB who have Turner syndrome may exhibit different signs and symptoms. Turner syndrome may not be immediately evident in some patients, but in other cases, it can manifests physically in a number of ways from an early age.

The most common sign of Turner syndrome that almost all teenagers, young adults, and adolescents experience is ovarian insufficiency, followed by ovarian failure. Ovarian failure can occurat birth or develop gradually in early childhood, adolescence, or early adulthood. The symptoms and indicators include:

1. Reduced growth
2. No childhood development spurts at the anticipated times
3. Adult height significantly lower than one could expect compared to a family member AFAB 
4. No sexual changes as anticipated with puberty
5. "Stalls" in sexual development throughout adolescence
6. The inability to conceive without fertility treatment²

Hearing loss in Turner Syndrome

People with Turner Syndrome often experience both sensorineural and conductive hearing loss. The karyotype affects the outer, middle, and inner ears equally and is associated with hearing loss and ear malformations.

Sensorineural hearing loss (SNHL) 

Internal issues are present in the inner ear. Air conduction and bone conduction can both vary from weak to profound, and to roughly an equal extent. Patients with TS typically experience symptoms during their 20s and 30s, though they can also appear as early as the age of 6. More than 90% of people with TS in their forties have some degree of hearing loss, and more than 25% of them require hearing aids. This hearing loss can progressively worsen over time.

Conductive hearing loss 

1. Issues with the middle or outer ear
2. Hearing by bone conduction is within normal limits
3. Mild to moderately severe hearing loss might result from issues with air conduction.
4. The early location of the Eustachian Tube in childhood makes ear infections and otitis media (fluid in the middle ear) prevalent

Due to ear deformities and malformations, children with TS are believed to be predisposed to middle ear disorders and are at a higher risk of developing them.

 Mixed hearing loss

1. Issues with the inner ear as well as the middle and/or outer ears
2. Both air conduction and bone conduction problems cause hearing loss
3. Issues with air conduction contribute more to the loss of hearing compared to bone conduction³

Pathophysiology of hearing loss in Turner syndrome

1. Abnormalities in the auditory pathway: one of the X chromosomes, which is essential for the development of the auditory system, is absent or deformed in TS. Sensorineural hearing loss (SNHL) can be brought on by inner ear abnormalities that interfere with the transmission of sound signals
2. Middle ear anomalies: luid buildup and chronic ear infections can result from anatomical abnormalities in the middle ear bones and dysfunctional eustachian tubes, which can cause conductive hearing loss (CHL)
3. Recurrent otitis media (middle ear infections): chronic inflammation and damage can result from recurrent middle ear infections brought on by eustachian tube dysfunction, which exacerbates hearing loss
4. Eustachian tube dysfunction: hearing loss and an increased risk of infection can result from inadequate ventilation and fluid accumulation in the middle ear⁴

Diagnosis tools and methods

Based on indications and symptoms, the child's chromosomes will be analyzed in a lab test if the doctor believes they have Turner syndrome. A blood sample is required for the test. The doctor may also occasionally request a skin sample or cheek scrape.

An elevated risk of Turner syndrome may also be indicated by prenatal screening procedures that analyze the fetus's DNA in the mother's blood.

Turner syndrome can be detected in utero (in the womb) using one of two methods:

1. Chorionic villus sampling: this involves taking a small sample of tissue from the growing placenta, as the baby's genetic material is present in the placenta as well. The chorionic villus cells are then submitted to the genetics lab for chromosome analysis. Typically, this is carried out between weeks 11 and 14 of pregnancy
2. Amniocentesis: an amniotic fluid sample is extracted from the uterus for this examination. The amniotic fluid contains the baby's shed cells; the chromosomes in these cells can be examined in the genetics lab. Usually, this is carried out after 14 weeks of pregnancy⁵

Management and treatment strategies

There is currently no cure for Turner syndrome. However, some drugs and treatments can help control its symptoms.

Treatment for Turner syndrome frequently focuses on hormone therapy in addition to treating associated medical issues (such as cardiac disorders). The possible treatments are:

1. Human growth hormone therapy: vertical growth is assisted by human growth hormone injections. These injections can add several inches to your child's eventual height if treatment is started early enough
2. Estrogen therapy: People with TS frequently have low sex hormone (estrogen) levels, which affects the growth of their sexual characteristics. Menstruation and breast growth are aided by estrogen. The growth of the brain, heart, liver, and bones are all enhanced by estrogen replacement therapy
3. Cyclic progestins: These drugs cause menstruation to flow regularly, and healthcare providers usually offer them when the patient is eleven or twelve years old

Turner syndrome cannot be avoided in any way. At conception, it occurs at random. It's not the biological parents' fault and they are powerless to stop it from happening.⁶

Current research and future directions

Comprehending the genetic foundation of hearing impairment

Current research endeavours to identify certain genes implicated in hearing loss associated with Turner Syndrome. Understanding the underlying mechanisms and identifying these genes may reveal possible sites of intervention.

Prospects for gene therapy

 Research on gene therapy is looking into ways to make up for or fix the genetic defects linked to Turner Syndrome. Gene therapy shows promise as a treatment option for hearing loss at the genetic level, even though the technique is still in its infancy.

Cochlear implants

These devices can significantly enhance hearing for those with profound hearing loss. Technological developments in implants and surgery are improving results and widening patient eligibility.

Novel technologies for hearing aids

For those with Turner Syndrome, advances in hearing aid design and functioning are enhancing their quality of life. Enhancements, including better sound processing, increased comfort, and communication with other devices, are contributing to the effectiveness and user-friendliness of hearing aids.⁷ 

Summary

Hearing loss is common in Turner syndrome. Middle ear problems start in early childhood, and hearing loss occurs within the first ten years of life. If neither condition is identified and addressed early on, it may lead to auditory impairment and social handicap (such as speech impediment or even intellectual development). Treatment of TS patients' auditory difficulties with diligence and appropriateness is the only effective technique to reduce hearing loss in these patients.