This study will try to identify and understand the genetic factors that lead to an inner ear
malformation called "enlarged vestibular aqueducts", that can be associated with hearing
Patients with sensorineural hearing loss with or without inner ear malformations and their
parents and siblings may be eligible for this study. Participants and their immediate family
members, may undergo some or all of the following tests and procedures:
- Medical and family history, including questions about hearing, balance and other
ear-related issues, and review of medical records.
- Routine physical examination.
- Blood draw or buccal swab (brushing inside the cheek to collect cells) - Tissue is
collected for DNA analysis to look for changes in genes that may be related to hearing
- Hearing tests - The subject listens for tones emitted through a small earphone.
- Balance test (VEMP) to see if balance functions of the inner ear are associated with the
hearing loss Electrodes will be placed behind your ear and at the base of your neck.
From a reclining position, you will be asked to raise your head while clicking sounds
are played into your ears. - Ultrasound tests - An inner ear malformation called EVA
(enlargement of the vestibular aqueduct) indicates that a genetic disorder called
Pendred syndrome may be the cause. Because thyroid abnormalities are also associated
with Pendred syndrome, an ultrasound examination of the thyroid gland may be done.
- Computed tomography (CT) and magnetic resonance imaging (MRI) scans - These tests show
the structure of the inner ear. For CT, the subject lies still for a short time while
X-ray images are obtained. For MRI, the patient lies on a stretcher that is moved into a
cylindrical machine with a strong magnetic field. The magnetic field and radio waves
produce images of the inner ear. The radio waves cause loud thumping noises that can be
muffled by the use of earplugs.
Nonsyndromic hereditary hearing impairment is a genetically heterogeneous disorder that can
be caused by mutations in any one of at least 60 different genes. Enlargement of the
vestibular aqueduct (EVA) is a radiologic finding known to be associated with mutations in
one of these genes, the Pendred syndrome gene (SLC26A4, formerly known as PDS). EVA may thus
serve as a clinically useful marker to facilitate the diagnosis of hearing impairment. Recent
data from our laboratory and others indicates that only a subset of individuals with EVA have
SLC26A4 mutations, and therefore some EVA cases are likely to be caused by other genes,
nongenetic factors, or a combination of these etiologies. Families with two or more
individuals with hearing impairment and EVA will be enrolled in this study in order to
identify other genetic factors that cause EVA. Siblings and parents may also be enrolled in
order to define inheritance and to perform molecular genetic analyses.
- INCLUSION CRITERIA:
Subjects must have or be a family member of a participant with known or non-syndromic SNHL
associated with inner ear malformations
There must be at least two participating affected family members.
Adults must be able to provide informed consent
Minors must have a parent or guardian able to provide consent
Age between 0-99.
Subjects with known exposure to physical or chemical teratogens in utero that could account
for their inner ear malformations such as thalidomide or radiation
Any hearing loss that is associated with syndromes, such as, branchio-oto-renal (BOR)
syndrome, which comprises system malformations and branchial cleft abnormalities and is
caused by heterozygous mutations in the EYA1 gene.
Previous genetic testing identifying two pathogenic mutant alleles of SLC26A4.