congenital deafness of genetic origin

7/25/2019 Congenital Deafness of Genetic Origin

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CONGENITAL DEAFNESS OF GENETIC ORIGIN

(Occuring Alone)

MICHELS APLASIA MONDINIS DYSPLASIA SCHEIBES DYSPLASIA ALEXANDERS AP

Bilateral absence of the parts of the inner ear (cochlea andsemicircular canal)

Also known as complete labyrinthine aplasia (CLA)

Characterized by bilateral absence of differentiated

inner ear structures with resultant anacusis (deafness)

Results from mutation of FGF3 gene on chromosome

11q13

Autosomal dominant (Boies), Autosomal recessive

(internet)

Associated with abnormal development of the skeletal

portions of the 2nd

arch (absent round and oval window,

abnormal course of CN VII) and skull base abnormalities

(hypoplasia of petrous temporal bone, platybasia (flat skull

base with angle >143), aberrant course of jugular veins)

Abnormality of your cochlea

Results in a flattened cochlea with the

development of only the basal turn so that

instead of the normal 2 turns there are only 1

turns while the middle and apical turns

occupy a common space

Almost all have absent vestibular function on

the affected side

Completely deaf on the affected side

Autosomal dominant

Cochleosaccular dysplasia.

The saccule between the cochlea and

semicircular canals is missing. Wala siya sang

cochlea and saccule.

Bony labyrinth is fully developed but the

pars inferior (saccule and cochlear duct) isrepresented by mounds of undifferentiated

cells

Most common of all inherited congenital

deafness

Autosomal Recessive

Some residual hearing in low frequencies

Involves chiefly the Organ of C

nga wala unod. No d

Characterized by aplasia of t

Prominently affects the

particularly the basal turn

adjacent ganglion cells Hearing loss is most n

frequencies

Preserved low-frequency he

CONGENITAL DEAFNESS OF GENETIC ORIGIN (WITH OTHER ABNORMALITIES)

WAARDENBURG SYNDROME PENDREDS DISEASE USHERS SYNDROME

Hallmark of this disease is BLUE EYE

Rare genetic disorder most often characterized by varying degrees of

deafness, minor defects in structures arising from neural crest and

pigmentation anomalies

Most mutations lead to abnormal melanocytes

Features: lateral displacement of the medial canthi and lacrimal points,

a flat nasal root, hyperplasia of the eyebrows, partial or total

heterochromia of the rides, partial albinism in the form of a white

forelock, and congenital deafness in approximately of these patients.

Autosomal dominant

SENSORINEURAL HEARING LOSS (SNHL) WITH HYPOTHYROIDISM

Frequently cause by abnormalities in pendrin, a protein

essential for the transport of anions like chloride, iodied and

bicarbonate

Associated with severe hearing loss and nonendemic goiter

Accounts for 10% of the cases of recessive hereditary deafness

Caused by mutation of any of the 11 ge

Resulting to hearing loss and visual impa

Most common condition that affects both hearing

Characterized by severe to moderate bilateral sens

loss and retinitis pigmentosa

Types

o Type 1- profoundly deaf at birth and have serv

o Type 2- moderate to severe hearing loss and n

o Type 3- normal at birth; progressive loss in chil


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CHROMOSOMAL ABNORMALITIES

TRISOMY 13 (PATAU), TRISOMY 14 (MOSAIC), TRISOMY 15 TRISOMY 18 (EDWARDS SYNDROME) TRISOMY 21 (DOWNS SYNDRO

Low set ears, undifferentiated pinnae, absence of the external audiotyr

canles or middle ear, cleft lip, cleft palate, microphthalmia, coloboma

irides, and aplasia of the optic nerve

Infants die within a short time

Low-set ears, malformed pinnae, micrognatthia, flexion of the

index finger over the third finger and prominent occiput

Leads to failure to thrive and death during infancy

Low-set ears, flattened nose, narrow roof of mout

narrow roof of mouth, macroglossia, simian creas

umbilical hernia, sandal gap (wide space between

toes)

CONGENITAL DEAFNESS OF NON-GENETIC ORIGIN

RUBELLA ERYTHROBLASTOSIS FETALIS CRETINISM

Most Common along with Erythroblastosis Fetalis and Cretinism. Rubella most

common in docs experience

Classic Triad: cataract, cardiac abnormalities and deafness

When the insult occurs during the first trimester, the probability is the

development of sensorineural hearing loss.

Pathologic examination shows aplasia of the organ of Cortia nd of the

saccule (pars inferior).

Pars superior is generally normal

Characterized by deposition of bilirubin in CNS, and jaundice,

mental retardation, cerebral palsy, and deafness shortly after

birth

Postpartum exchange transfusion is the treatment of choice

but the child may still have residual high-tone sensorineural

hearing loss

Due to iodine deficiency

Endemic in mountainous areas like the Alps a

Hearing loss is mixed type


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DELAYED OR ACQUIRED GENETIC DISORDERS

ALPORTS DISEASE Autosomal dominant

Due to mutations in genes involved in the synthesis of type IV collagen

Characterized by GN, eye abnormalities and bilateral, symmetric and high-frequency hearing loss

More common in males

VON RECKLINGHAUSENS DISEASE Neurofibromatosis1

Diagnosis: 2 out of 7

o 6 caf au lait spots 5 mm in prepubertal children and 15 mm postpubertal

o >2 axillary or inguinal freckles

o 2 typical neurofibromas or one flexiform neurofibroma

o Optic nerve glioma

o 2 Lisch nodules

o

Sphenoid dysplasia or typical long-bone abnormalities like pseudoarthrosis

First-degree relative (parents, siblings) with NF-1

CROUZONS SYNDROME Characterized by premature fusion of certain skull bones (craniosynostosis) preventing the skull from growing normally and affects the shape

HURLER SYNDROME Begins in early childhood

Results in skeletal deformity, dwarfism, mental retardation, splenomegaly, hepatomegaly, blindness and profound sensorineural hearing

Sex-linked recessive

KLIPPEI-FEIL SYNDROME Bone disorder characterized by abnormal fusion of two or more bones in the cervical vertebrae, spina bifida, scoliosis and torticollis

Features: short neck, appearance of low hairline at the back of the head and limited ROM in the neck

Autosomal recessive

May also have vestibular dysfunction and profound sensorineural hearing loss


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REFSUMS DISEASE Neurocutaneous syndrome characterized biochemically by accumulation of phytanic acid due to absence of phytanol-CoA hydroxalase

Symptoms develop progressively and slowly including peripheral neuropathy, tinnitus, anosmia, failing vision, nyctalopia and hearing los

Ichthyosis may accompany, but most often follows the occurrence of the above symptoms

Autosomal recessive

ALSTROMS DISEASE Retinitis pigmentosa, DM, obesity and progressive deafness that may start at age 10

Autosomal recessive

PAGETS DISEASE Also known as osteitis deformans

Localized disorder of bone remodeling that typically begins with excessive bone resorption followed by increase bone formation lead

bone

Bone pain is the most common symptom

Begins in the middle age

Autosomal dominant

RICHARD-RUNDLE SYNDROME Mental deficiency, ataxia, hypogonadism and severe deafness

Hearing loss is total by age 5 or 6

Autosomal recessive

congenital deafness of genetic origin

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