History and Cause

Usher syndrome was probably described for the first time in 1858 by Albrecht von Gräfe, a pioneer of modern ophthalmology. He reported the case of a deaf patient with retinitis pigmentosa, who had two brothers with the same symptoms. A short time later, one of his students, Richard Liebreich, examined the population of Berlin for disease pattern of deafness with retinitis pigmentosa. He already stressed the recessive nature of this illness, since the cases of blind-deafness combinations occurred particularly in the siblings of blood-related marriages or in families with patients in different generations. Additionally his observations supplied the first proofs for the coupled transmission of the disease, since no cases of isolated blindness or deafness in the family trees could be found.

Finally the disease pattern was designated after the British ophthalmologist Charles Usher, who examined the pathology and transmission of this illness in 1914 on the basis of 69 cases.

With the advancement of the scientific methods, the genetic heterogeneity of the Usher syndrome was described toward the end of the 20th century. Using linkage analysis of patient families several independent loci on different chromosomes were identified, in whom hereditary defects, which cause the Usher syndrome, were found. With the help of these loci the illness was divided in twelve subtypes (USH1A-G, USH2A-C, USH3A). In nine cases the concerned gene could be found by sequencing the candidate genes in these locations. On the other hand, it could be shown that one Usher subtype - USH1A on chromosome locus 14q32 - was incorrectly determined and does not exist.

Using interaction analysis techniques it could be shown that the identified gene products interact with one another in one or more larger protein complexes. If one of the components is missing, this protein complex cannot fulfill its function in the living cell and it probably comes to the degeneration the same. The function of this protein complex has been suggested to participate in the signal transduction or in the cell adhesion of sensory cell.

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