Genetic Hearing Loss Associated with External Ear Abnormalities

Question 1

What is treacher collins syndrome?

Answer 1

First or second brachial arch syndrome
40% of cases are AD with variable expressivity and 100% penetrance
60% cases new mutations, with fathers tending to be older
Majority of mutations are deletions or nonsense mutations

Question 2

What are some clinical features of treacher collins?

Answer 2

Poor development of zygomatic bones & mandible (receding chin)
Coloboma of iris or lower eyelids and absent lower eyelashes
Characteristic large fish-like mouth due to deficiency of muscles of upper lip and small lower jaw
Facial nerve anomalies reported
Intelligence usually normal, but mild intellectual disability is reported

Question 3

What are the audiologic findings for treacher collins?

Answer 3

Malformed pinna and external auditory canal atresia
Absent or malfomed ossicles especially the stapes
Complete absence of ME cavity reported, which may be filled with connective tissue
Mild to moderate bilateral conductive hearing loss in > 50% of cases
Rarely, SNHL reported

Question 4

What is the treatment for treacher collins?

Answer 4

Requires multidisciplinary approach
Cleft palate repaired at 9 to 12 months of age
Hearing loss treated by bone conduction amplification or BAHA
Speech therapy and educational intervention

Question 5

What is the differential diagnosis for treacher collins?

Answer 5

Oculo-auriculo-vertebral spectrum (OAV) disorder

Question 6

What is branchio-oto-renal (BOR) syndrome?

Answer 6

Second most common cause of AD hearing loss
Variable expressivity
Affects structures developing from branchial arches, ears, and kidneys

Question 7

What are the clinical features of BOR?

Answer 7

Renal anomalies (65% to 80%) including large, polycystic kidneys
Facial nerve anomalies reported in < 5% of individuals but rarely leads to facial paralysis

Question 8

What are the audiologic findings of BOR?

Answer 8

Conductive, SNHL, or mixed hearing loss (90%)
Persistent branchial cysts/fistulas (60%), commonly present in lower 1/3 of the neck
Malformation of pinna (35%)
External auditory canal stenosis (30%)
Ossicular deformities including stapes fixation
Deformities of the inner ear including Mondini’s malformation
Vestibular anomalies rare and include reduced caloric response
All three types of hearing loss can be seen in members of the same family
Could occur later in life, but typically is not progressive in life

Question 9

Can BOR affect pregnancy?

Answer 9

Yes
Oligohydramnios can occur (low amniotic fluid)
Can affect the development of the fetus
After about four months of pregnancy, the kidneys of a normal fetus will produce amniotic fluid
If the fetus has kidney abnormalities, the amount of amniotic fluid may be too low

Question 10

What is the differential diagnosis of BOR?

Answer 10

Alport syndrome
Involves the kidneys and the eyes
Glomerulonephritis (inflammation of the kidneys)

Question 11

What is Oculo-Auriculo-Vertebral (OAV) spectrum disorder?

Answer 11

A complex of 3 rare congenital disorders believed to be related: Goldenhar Syndrome (most severe form)
Hemifacial Microsomia (HFM) (intermediate form)
Oculo-Auriculo-Vertebral Disorder (mildest form)
Mulitfactorial inheritance pattern
Chromosomal analysis is normal
Associated with sporadic gene mutations
May not be inherited but seems to cluster in families
This complex is a predominantly unilateral malformation of craniofacial structures developing from 1st & 2nd branchial arches

Question 12

What are some clinical features of OAV?

Answer 12

Unilateral facial and mandibular hypoplasia, and cleft palate common
Even with bilateral involvement, one side of face more severely affected
Nearly all cranial nerves involved including VII N resulting in facial weakness or paralysis
Congenital cardiac anomalies are common
Vertebral anomalies include scoliosis, spina bifida, and rib anomalies
Mental retardation is uncommon
The life span is normal
Deafness/blindness in one or both ears/eyes can occur
Internal organ(s) can either be unilaterally absent or underdeveloped

Question 13

What are the audiologic findings of OAV?

Answer 13

Pinna anomalies including preauricular tags, microtia, stenosis of EAC
Conductive hearing loss more common but rarely SNHL can occur

Question 14

What is the differential diagnosis for OAV?

Answer 14

Treacher collins

Question 15

What does CHARGE stand for?

Answer 15

Coloboma of the eye
Heart defects
Atresia of nasal choanae
Retarded of growth and/or development
Genital and/or urinary abnormalities
Ear anomalies or deafness

Question 16

What are the ear anomalies that occur in CHARGE?

Answer 16

Typically SNHL and progressive
External ear anomalies (maybe too floppy to support HAs)
Ossicular malformations with almost universal ET dysfunction
Mondini anomaly
Hypoplastic semicircular canals with balance issues
Considered a deaf/blind syndrome although complete deafness or blindness is uncommon

Question 17

Do you need to have all of these characteristics present to be diagnosed with CHARGE?

Answer 17

No
You need to have a few of them

Question 18

Is the lifespan effected with CHARGE?

Answer 18

No

Question 19

What are some other findings for CHARGE that are not in the name?

Answer 19

Cranial nerve dysfunction including facial palsy
Renal abnormalities
Behavioral issues that may be brought on by sensory deprivation
Attention deficit disorder, autistic-like behaviors
Intellectual disability from mild to severe
Infertility
Prone to allergies such as food and latex
A significant percentage have no symbolic communication

Question 20

How is CHARGE inherited?

Answer 20

Unknown, most likely heterogeneous; most cases sporadic
Risk may be increased by increased paternal age
If it were genetic, it would be AD

Question 21

Is a multi-disciplinary team required to treat children with CHARGE?

Answer 21

Yes

Question 22

What transmission does treacher collins have?

Answer 22

AD