Deafness, Congenital, with Inner Ear Agenesis, Microtia, and Microdontia

Alternative Names

  • Deafness, Congenital, with Labyrinthine Aplasia, Microtia, and Microdontia
  • Deafness with LAMM
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WHO-ICD-10 version:2010

Congenital malformations, deformations and chromosomal abnormalities

Congenital malformations of eye, ear, face and neck

OMIM Number

610706

Mode of Inheritance

Autosomal recessive

Gene Map Locus

11q13.3

Description

Congenital Deafness with Labyrinthine Aplasia, Microtia, and Microdontia (LAMM) is a genetic disease that affects development of the ears and teeth. This condition is characterized by profound bilateral congenital sensorineural deafness associated with inner ear anomalies, microtia type I that is typically bilateral, and microdontia. The diagnosis is based on clinical findings, and can be confirmed by testing the mutations of FGF3 gene.

Molecular Genetics

Deafness with Labyrinthine Aplasia, Microtia, and Microdontia disease follows an autosomal recessive pattern of transmission. The causative gene is FGF3, located on 11q13.3 chromosome. Mutations in this gene result in loss of FGF3 function, which impairs the development of the ears and teeth; the characteristic features of LAMM syndrome.

Epidemiology in the Arab World

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Other Reports

Saudi Arabia

Alsmadi et al. (2009) studied a large extended consanguineous Saudi family with Deafness with LAMM. The proband was a 4-year-old girl, who presented with prominent tip of the nose, dysplastic ears, bilateral type 1 microtia, and microdontia with widely spaced teeth. Her ears were low set and anterverted. Dysplastic ear changes were asymmetrical and more pronounced in the upper half. Her both external auditory meatuses were patent with no stenosis. All the affected members (21 individuals) presented with hearing impairment and communicated with sign language. They all had the same facial, auricular, and dental features as of the proband with some intrafamilial variability in the severity of these features. Incisors and canine teeth were small and misaligned with increased space between the teeth. In addition, they had ear abnormalities with asymmetrical involvement and more prominent dysplastic changes in the upper half of the ear and helix. Otoacoustic emissions, indicating outer hair cell dysfunction, and brainstem auditory evoked potentials were absent, indicating profound deafness. On brain imaging, the right side vestibular and cochlear system were not visualized, whereas the left side had a cystic vestibulum. Inner ear structure revealed absent cochlea and no semicircular canals bilaterally. Neural structures also appeared to be absent. All affected family members were descendants of a common ancestor who had lived six generations ago in a geographically isolated small village.

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