Research

Saima Riazuddin

Laboratory of Molecular Genetics

Deafness is one of the most prevalent forms of sensory impairment with profound consequences for the individual and society. Deafness can be due to genetic and environmental factors.  Projects in the Laboratory of Molecular Genetics (LMG) are geared toward identifying deafness genes through genetic analysis of extended human families, screening for candidate genes through sequencing, in vitro and semi in vivo functional analysis of the wild and mutant gene, investigating gene expression in the normal and hearing impaired ear through in situ and real time PCR experiments, and determining the localization of various proteins in the inner ear through immunohistochemistry. Using mouse as a model, deafness phenotype of human are being recapitulated. The mutant mice are being evaluated for their hearing phenotype.

The inner ears of the mutant mice are analyzed for pathogenic and anatomic defects of cochlea resulting from pathogenic mutations in genes associated with deafness.

The above proposed studies are aimed to answer the following broad questions:

• What are the genetic factors that determine hearing sensitivity?
• How do the pathogenic mutations in disease genes affect the inner ear structure and function?
• What are the precise mechanisms of various forms of hearing dysfunction?
• What molecules or genetic factors can antagonize the effect of disease gene?

Zubair Ahmed

Visual and Auditory Perception: From Human Genetic to Model Systems

Our laboratory identifies and characterizes genes that control the function of the visual and auditory sense organs of mammals through the study of individuals with Usher syndrome. Usher syndrome (USH), defined by a bilateral sensorineural deafness that originates in the cochlea (the auditory sensory organ) and a loss of vision due to retinitis pigmentosa, is the most frequent cause of deafness accompanied by blindness. The study of USH may offer a unique opportunity to decipher the molecular bases of some of the developmental and functional similarities existing between the retinal and the cochlear sensory cells. Our lab uses molecular biologic and genetic approaches, human and mouse models, as well as heterologous cell culture expression systems.

Current projects include:

• Identification and characterization of genes for Usher syndrome
• Genetic linkage studies of genes for Usher in South Asian families
• The biological role of the protocadherin 15 in sound and vision perceptions
• The identification of proteins interacting with protocadherin 15
• Characterization of LRTOMT-one gene, two proteins