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Hearing loss - Genetics evaluation

Why was my child referred to genetics?

The main goal of a genetics visit is to understand the cause of your child’s hearing loss.  

Some types of hearing loss can be related to other health conditions. A genetics visit can help find out if your child is at risk for other health problems. You can also find out if there is a chance for other people in your family to have hearing loss, including future children. Most children with hearing loss are referred to the genetics clinic even if there is no family history of hearing loss.

What happens at a genetics visit?

A genetics nurse practitioner or doctor will meet with you and your child. They will ask you how the hearing loss was found and what studies have been done. They will ask about your child’s medical history, including pregnancy, surgeries and illnesses. They will do a routine physical exam. You will have time to talk about medical and developmental concerns including any learning disabilities.

A genetic counselor will talk with you before or during the appointment. They will draw a family tree (pedigree) and ask questions about both sides of the family’s medical history. 

At the end of the visit, the nurse practitioner or doctor may recommend more tests. They may ask to take a photo of your child for the medical record. Most visits last about 1-1 ½ hours. You will have time to ask questions and learn about the different types of hearing loss and possible causes.

What testing might be recommended?

Recommendations can vary from child to child, but might include:

  • Eye exam by pediatric ophthalmologist
  • Electrocardiogram (EKG) – monitors the heart beat
  • Genetic testing (blood sample)
  • Urinalysis (urine test)

There are many different genes that can cause hearing loss. Different tests may be done. Two genes, connexin 26 and connexin 30 are common causes of non-syndromic hearing loss (hearing loss without any other signs and symptoms). If a specific syndrome is being considered, tests may be done for that.

Some children benefit from imaging of the inner ear. Your child’s otolaryngologist (ENT doctor) will discuss the risks and benefits of imaging studies.

After the visit: 

You will get a copy of the clinic note 1-2 weeks after the visit. Your pediatrician or family doctor, ENT, and eye doctor will also get a copy. The clinic note has a summary of your child’s medical history, and information learned from the physical exam. Certain features noted may be important when looking at syndromes that cause hearing loss.

Most children have at least one follow up visit. If a cause of hearing loss is identified, you will be invited back for education. If all initial testing is negative/normal, you will be invited back to consider other causes of hearing loss.

Can a cause for hearing loss always be found?

Not always. About half of all childhood hearing loss is genetic, but the exact cause is not always identified. Another 20-25% of cases are due to environmental factors, while 25-30% of cases have an unknown cause.

What are different types of hearing loss?

There are three main types of hearing loss; these are sensorineural hearing loss, conductive hearing loss and mixed hearing loss.

Sensorineural Hearing Loss (SN) comes from a malfunction of inner ear structures (cochlea).

Conductive Hearing Loss comes from abnormalities of the external ear and/or the ossicles of the middles ear. Ossicles are the three small bones in the ear that transmit sounds into the inner ear.

Mixed Hearing Loss is a combination of conductive and sensorineural hearing loss. It includes malfunctions/abnormalities of both the inner and outer ear structures.

What are the main causes of hearing loss?

There are three main causes of hearing loss: syndromic hearing loss, non-syndromic hearing loss, and environmentally caused hearing loss.

Syndromic hearing loss is hearing loss associated with malformations of the external ear or with medical problems involving other organ systems.

Non-syndromic hearing loss is hearing loss not associated with any visible abnormalities of the external ear or any other related medical problems.

Environmentally caused hearing loss is caused by exposures to a child, both before and after birth. Environmental causes can be prematurity, alcohol exposure during pregnancy, infections during pregnancy or after birth, or medicines that damage the auditory nerve.

More specific environmental causes can include preeclampsia, prematurity, Rh incompatibility complications, prenatal inflections such as toxoplasmosis, rubella, cytomegalic virus, and herpes, and infections after birth like bacterial meningitis. Medicines that can damage the auditory nerve include antibiotics like gentamicin, and certain types of chemotherapy drugs that can damage the inner ear.

Resources

Children’s Hospital Specialty Center
Genetics and Genomics Program
2530 Chicago Avenue South
Minneapolis, MN 55404
612-813-7240

Questions?

This information is not specific to your child but provides general information. If you have any questions, please ask the doctors or nurses. For more reading material about this and other health topics, please call or visit the Family Resource Center library.

Last Reviewed 4/2016

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This page is not specific to your child, but provides general information on the topic above. If you have any questions, please call your clinic. For more reading material about this and other health topics, please call or visit Children's Family Resource Center library, or visit www.childrensmn.org/educationmaterials.

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