What are the other Names for this Condition? (Also known as/Synonyms)

• Congenital Corneal Dystrophy, Progressive Sensorineural Deafness
• Corneal Dystrophy and Sensorineural Deafness
• Harboyan Syndrome

What is Corneal Dystrophy and Perceptive Deafness? (Definition/Background Information)

• Corneal Dystrophy and Perceptive Deafness (CDPD) or Harboyan Syndrome is a degenerative corneal disorder characterized by the association of congenital hereditary endothelial dystrophy (CHED) with progressive, postlingual sensorineural hearing loss
• The ocular manifestations in CDPD include diffuse bilateral corneal edema occurring with severe corneal clouding, blurred vision, visual loss and nystagmus
• They are apparent at birth or within the neonatal period and are indistinguishable from the ocular findings characterizing autosomal recessive CHED (CHED2)
• Hearing deficit in CDPD is slowly progressive and is typically identified in patients between 10 and 25 years of age
• There are no reported cases with prelingual deafness, however, significant hearing loss in children as young as 4 years old has been detected by audiometry, suggesting that hearing may be affected early in the disease course, even at birth
• To date, 24 cases from 11 families of various origins (Asian Indian, South American Indian, Sephardi Jewish, Brazilian Portuguese, Dutch, Gypsy, Moroccan and Dominican) have been reported
• A variety of genetic, metabolic, developmental and acquired diseases presenting with clouding of the cornea should be considered in the differential diagnosis (Peters anomaly, sclerocornea, limbal dermoids and congenital glaucoma)
• Audiometry must be performed to differentiate CDPD from CHED2. Autosomal recessive types of CHED (CHED2) and CDPD should be carefully distinguished from the less severe autosomal dominant type, CHED1

(Source: Corneal Dystrophy and Perceptive Deafness; Orphanet, National Institute of Health and Medical Research (INSERM), Paris.)

Who gets Corneal Dystrophy and Perceptive Deafness? (Age and Sex Distribution)

• Corneal Dystrophy and Perceptive Deafness is an extremely rare congenital disorder. The presentation of symptoms may occur before or shortly after birth
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Corneal Dystrophy and Perceptive Deafness? (Predisposing Factors)

• A positive family history may be an important risk factor, since Corneal Dystrophy and Perceptive Deafness can be inherited
• Currently, no other risk factors have been clearly identified for CDPD

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Corneal Dystrophy and Perceptive Deafness? (Etiology)

• CDPD is caused by mutations in the SLC4A11 gene located at the CHED2 locus on chromosome 20p13-p12, indicating that CHED2 and CDPD are allelic disorders
• A total of 62 different SLC4A11 mutations have been reported in 98 families (92 with CHED2 and six with CDPD)

(Source: Corneal Dystrophy and Perceptive Deafness; Orphanet, National Institute of Health and Medical Research (INSERM), Paris.)

What are the Signs and Symptoms of Corneal Dystrophy and Perceptive Deafness?

• The ocular manifestations in Corneal Dystrophy and Perceptive Deafness include diffuse bilateral corneal edema occurring with severe corneal clouding, blurred vision, visual loss and nystagmus
• They are apparent at birth or within the neonatal period and are indistinguishable from the ocular findings characterizing autosomal recessive CHED (CHED2)
• Hearing deficit in CDPD is slowly progressive and is typically identified in patients between 10 and 25 years of age
• There are no reported cases with prelingual deafness, however, significant hearing loss in children as young as 4 years old has been detected by audiometry, suggesting that hearing may be affected early in the disease course, even at birth

(Source: Corneal Dystrophy and Perceptive Deafness; Orphanet, National Institute of Health and Medical Research (INSERM), Paris.)

The signs and symptoms of Corneal Dystrophy and Perceptive Deafness may include: (Very frequently present symptoms in 80-99% of the cases)

• Corneal dystrophy
• Corneal opacity: Opacification of the corneal stroma
• Sensorineural hearing impairment
• Visual impairment
• Nystagmus

(Source: Corneal Dystrophy and Perceptive Deafness; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Corneal Dystrophy and Perceptive Deafness Diagnosed?

• The diagnosis of Corneal Dystrophy and Perceptive Deafness is based on clinical criteria, detailed ophthalmological assessment and audiometry. Molecular confirmation of the clinical diagnosis is feasible
• A variety of genetic, metabolic, developmental and acquired diseases presenting with clouding of the cornea should be considered in the differential diagnosis (Peters anomaly, sclerocornea, limbal dermoids and congenital glaucoma)
• Audiometry must be performed to differentiate CDPD from CHED2. Autosomal recessive types of CHED (CHED2) and CDPD should be carefully distinguished from the less severe autosomal dominant type, CHED1

(Source: Corneal Dystrophy and Perceptive Deafness; Orphanet, National Institute of Health and Medical Research (INSERM), Paris.)

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Corneal Dystrophy and Perceptive Deafness?

The complications of Corneal Dystrophy and Perceptive Deafness may include:

• Loss of vision
• Loss of hearing
• Decreased quality of life

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Corneal Dystrophy and Perceptive Deafness Treated?

• The ocular abnormalities in patients with Corneal Dystrophy and Perceptive Deafness may be treated with topical hyperosmolar solutions
• However, corneal transplantation (penetrating keratoplasty) represents the definitive treatment. Corneal transplantation results in substantial visual gains and has a relatively good surgical prognosis
• Audiometric monitoring should be offered to all patients. Hearing aids may be necessary in adolescence

(Source: Corneal Dystrophy and Perceptive Deafness; Orphanet, National Institute of Health and Medical Research (INSERM), Paris.)

How can Corneal Dystrophy and Perceptive Deafness be Prevented?

Currently, Corneal Dystrophy and Perceptive Deafness may not be preventable, since it is a genetic disorder.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Corneal Dystrophy and Perceptive Deafness? (Outcomes/Resolutions) 

• The prognosis of Corneal Dystrophy and Perceptive Deafness is dependent upon the severity of the signs and symptoms and associated complications, if any
• Individuals with mild conditions have better prognosis than those with severe symptoms and complications
• Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Corneal Dystrophy and Perceptive Deafness:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/