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Mondini dysplasia


Other Names for this Disease
  • Familial nonsyndromal Mondini dysplasia (subtype)
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Overview



What is Mondini dysplasia?

What are the signs and symptoms of Mondini dysplasia?

What causes Mondini dysplasia?

Is Mondini dysplasia inherited?

Is genetic testing available for Mondini dysplasia?

How might Mondini dysplasia be treated?


What is Mondini dysplasia?

Mondini dysplasia is a type of inner ear malformation that is present at birth (congenital). Individuals with Mondini dysplasia have one and a half coils of the cochlea instead of the normal two coils.[1] It may occur in one ear (unilateral) or both ears (bilateral) and can cause varying degrees of sensorineural hearing loss, although most individuals have profound hearing loss.[1] The condition can also predispose affected individuals to recurrent meningitis.[2] It is caused by disruption in the embryonic development of the inner ear during the seventh week of gestation.[3] The condition may be isolated (occurring with no other conditions or malformations) or may occur with other ear malformations or a number of syndromes.[4] Treatment options may include surgical repair of the defect to prevent recurrent meningitis; amplification aids for those with residual hearing; and cochlear implantation.[5]
Last updated: 2/24/2012

What are the signs and symptoms of Mondini dysplasia?

Mondini dysplasia is a congenital malformation (present at birth). It may occur either unilaterally (in one ear) or bilaterally (in both ears). Most affected individuals have profound sensorineural hearing loss, but some individuals do have residual hearing.[1] There have also been reports of affected individuals having normal hearing.[6] Mondini dysplasia can also predispose to recurrent meningitis because the defect can act as a "port of entry" to the fluid that surrounds the brain and spinal cord (cerebrospinal fluid, or CSF). Sometimes, individuals are not diagnosed before several episodes of recurrent meningitis occur.[1] The condition may occur with other abnormalities of the ear or other organs, or it may be isolated. The severity of the physical abnormality does not appear to correlate with the severity of the signs and symptoms in affected individuals.[6]
Last updated: 2/24/2012

What causes Mondini dysplasia?

The underlying cause of Mondini dysplasia (MD) in most individuals appears to remain unclear. Some have suggested that retinoids (vitamin A) or other factors a fetus may be exposed to early in pregnancy have contributed to some cases of isolated MD (occurring with no other abnormalities). The potential role of these factors has created increased difficulty in determining the real cause of isolated MD.[4]

Mutations in the SLC26A4 gene cause both Pendred syndrome and DFNB4 (non-syndromic hearing loss with inner ear abnormalities), which are both associated with MD.[4][1] Though mutations in the SLC26A4 gene have also been found in individuals with enlarged vestibular aqueduct (EVA) with and without MD, studies have shown there does not appear to be a relationship between isolated MD and the SLC26A4 gene. Thus hearing impairment in individuals with isolated MD may be caused by factors other than mutations in the SLC26A4 gene.[4] More recently, a type of mutation called a microdeletion (a tiny loss of genetic material on a chromosome that may span several genes) involving the POU3F4 gene on the X chromosome was detected in some individuals with familial MD.[5]

In cases where Mondini dysplasia is associated with a specific syndrome, the cause of the syndrome in the affected individual is assumed to be related to the occurrence of MD in those cases. Syndromes that have been associated with MD include Klippel Feil syndrome, Pendred syndrome, DiGeorge syndrome, and some chromosomal trisomies.[1]
Last updated: 2/27/2012

Is Mondini dysplasia inherited?

Mondini dysplasia usually occurs sporadically as an isolated abnormality (occurring in only one individual in a family with no other abnormalities) but it can be associated with a variety of syndromes including Klippel Feil syndrome, Pendred syndrome, DiGeorge syndrome, Wildervanck syndrome, Fountain syndrome, Johanson-Blizzard syndrome, and some chromosomal trisomies.[1][7] These syndromes can be inherited in a variety of ways, but Mondini dysplasia may not occur in each affected individual. It has also has been reported in families with congenital sensorineural hearing loss, both with autosomal dominant and presumed autosomal recessive inheritance.[8] One study described familial nonsyndromic Mondini dysplasia in a mother, son and daughter with presumed autosomal dominant inheritance;[7] another study described familial nonsyndromic Mondini dysplasia in a family in which transmission was most consistent with autosomal recessive inheritance.[7] It has also been suggested that Mondini dysplasia may be associated with substances that may harm a developing fetus when a pregnant woman is exposed (teratogens) such as thalidomide or rubella.[7] Being that Mondini dysplasia has been associated with a variety of conditions, inheritance patterns, and both genetic and non-genetic causes, it appears to be inherited in some cases, with the inheritance pattern being dependent upon the underlying cause of the condition in each individual or family.
Last updated: 2/27/2012

Is genetic testing available for Mondini dysplasia?

Genetic testing may be available for Mondini dysplasia if it is associated with a specific syndrome for which genetic testing is available, or if a mutation has previously been identified in an affected individual in the family. Unfortunately, for many cases of isolated Mondini dysplasia, there is no clinical genetic testing available.

GeneTests lists the names of laboratories that are performing genetic testing for many conditions that may be associated with Mondini dysplasia. Please note that most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, if you are interested in learning more, you will need to work with a health care provider or a genetics professional.
Last updated: 2/27/2012

How might Mondini dysplasia be treated?

Surgery to repair the defect present with Mondini dysplasia is typically necessary to prevent recurrent meningitis.[3][5] Prophylactic antimicrobial therapy (such as antibiotics) to prevent infection and conjugate pneumococcal vaccination are helpful in reducing the formation of bacteria in affected individuals.[3] If an individual has residual hearing, hearing amplification aids may be useful.[6] The use of cochlear implants to treat patients with inner ear malformations such as Mondini dysplasia has been increasingly successful. Various results of cochlear implantation in individuals with Mondini dysplasia have been reported in the literature.[6]
Last updated: 2/27/2012

References
  1. Masri A. et al. Mondini malformation associated with diastematomyelia and presenting with recurrent meningitis. J Child Neurol. May 2011; 26(5):622-624.
  2. Kamata A, Obinata K, Kon N, Suganuma H, Niizuma T, Kinoshita K. Recurrent meningitis with Mondini dysplasia after the operation and vaccination. Pediatr Int. April 2010;
  3. Liu FC, Chen PY, Huang FL, Lee CY, Lin CF. Recurrent bacterial meningitis in a child with mondini dysplasia. Clin Pediatr (Phila). November 2009; 48(9):975-977.
  4. Huang S. et al. Extremely discrepant mutation spectrum of SLC26A4 between Chinese patients with isolated Mondini deformity and enlarged vestibular aqueduct. J Transl Med. September 2011; 9:167.
  5. Tullu MS, Khanna SS, Kamat JR, Kirtane MV. Mondini dysplasia and pyogenic meningitis. Indian J Pediatr. July 2004; 71(7):655-657.
  6. Daneshi A, Hassanzadeh S, Abasalipour P, Emamdjomeh H, Farhadi M. Cochlear implantation in Mondini dysplasia. ORL J Otorhinolaryngol Relat Spec. January-February 2003; 65(1):39-44.
  7. Griffith AJ et al. Familial Mondini dysplasia. Laryngoscope. September 1998; 108(9):1368-73.
  8. Arellano B, Ramírez Camacho R, García Berrocal JR, Villamar M, del Castillo I, Moreno F. Sensorineural hearing loss and Mondini dysplasia caused by a deletion at locus DFN3. Arch Otolaryngol Head Neck Surg. September 2000; 126(9):1065-1069.