Ahmed Lab

  • Usher Syndrome Project

    Identification and Characterization of Genes for Usher Syndrome Type I

    Deaf people often rely on their vision, and blind people often depend on their hearing to compensate for their sensorial losses. But individuals with Usher syndrome (USH), who suffer from both hearing loss and blindness, struggle immensely to perceive the world.

    USH type 1 (USH1) is genetically heterogeneous – it can be caused by any one of several genes. Research into the disease has identified seven loci, with known genes for five of them. However, there are known cases of USH1 that did not originate with mutations in these genes. One of our long-term research goals is to identify and characterize additional genes whose mutations may lead to USH1.

    Reaching this goal involves a number of steps. First, we identify individuals with USH1 and the genetic links to their family members. Once this genetic pedigree is identified, we look for mutations known to cause USH1. The research then moves to genome-wide screening for novel USH1 loci and positional cloning of the gene or genes responsible for the disease. Finally, we characterize the newly identified genes and their molecular products and pathways.

    Our long-standing collaborations with investigators in India and Pakistan – where cultural and socioeconomic factors make recessively inherited genetic diseases very common – have helped us tremendously in identifying genetic pedigrees where USH is prevalent.

    Through the study of these families, we recently mapped and identified a gene (USH1H) responsible for USH1 in humans. We are now developing a mouse model to study the function of the USH1H gene product in eyes and ears. We have also mapped two novel genetic loci for USH1 and are conducting positional cloning work to identify the genes for these two new loci.

 
  • Segregating mutation of a novel USH gene in one such family.

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    Segregating mutation of a novel USH gene in one such family.

    Image shows the segregating mutation of a novel USH gene in one such family.