Non-Syndrome Hereditary Hearing Impairment - Gene Mapping: India/Pakistan Protocol

This study is currently recruiting participants. (see Contacts and Locations)
Verified April 2014 by National Institutes of Health Clinical Center (CC)
Information provided by:
National Institutes of Health Clinical Center (CC) Identifier:
First received: June 19, 2006
Last updated: April 26, 2014
Last verified: April 2014

The incidence of hearing impairment in India and Pakistan is higher than in the United States. This can be attributed to several factors, including infection and high rate of inbreeding which may result in homozygosity for a rare recessive mutation. The average family size is larger in India and Pakistan when compared to the United States. In addition, there are more than 1 billion people in India while the population size of Pakistan is approximately 148 million. The ability to detect linkage is greatly enhanced in an extended inbred family. It is estimated that as many as 45% - 60% of marriages in Pakistan are between close relatives (the vast majority of marriages are to first cousins). While the percentage of consanguineous marriages are not as high in India as compared to Pakistan, the population size of India is much larger.

Hearing impairment is the result of abnormal ear development, abnormal ear function or both and yet little is known about the molecular mechanisms involved in the development and homeostasis of the inner ear. Although the genes for several recessive deafness loci have been identified, there are still many families segregating deafness that cannot be ascribed to one of the currently known genes. The purpose of this study is to continue to identify genes that cause nonsyndromic hereditary hearing impairment by enrolling families segregating deafness.

Hearing Impairment

Study Type: Observational
Official Title: Non-Syndromic Hereditary Hearing Impairment - Gene Mapping: India/Pakistan Protocol

Resource links provided by NLM:

Further study details as provided by National Institutes of Health Clinical Center (CC):

Estimated Enrollment: 24000
Study Start Date: July 1992
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Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No
  • Affected and unaffected members of families segregating deafness caused by genetic etiology.
  • Adults must be able to provide informed consent.
  • Adults must be able to provide informed consent for children who are at least two years of age
  • All communities, ethnicities, and races as found in Pakistan.


  • Persons with non-genetic forms of hearing loss likely due to acquired causes such as an infection, head or noise trauma, or exposure to an ototoxic drug will not be included in this protocol
  • Syndromic forms of inherited deafness are excluded if the gene for the disorder is known and there is no reason to believe the disorder is genetically heterogeneous.
  • Subjects cannot provide informed consent or have a parent/guardian that cannot provide consent.
  • Children under the age of two years will not be included in this study because an objective audiological examination such as an ABR analysis may require sedation, which is presently not feasible in Pakistan.
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00341874

Contact: Thomas B Friedman, Ph.D. (301) 496-7882

University of Punjab Recruiting
Lahore, Pakistan
Sponsors and Collaborators
Principal Investigator: Thomas B Friedman, Ph.D. National Institute on Deafness and Other Communication Disorders (NIDCD)
  More Information

Publications: Identifier: NCT00341874     History of Changes
Other Study ID Numbers: 999993016, OH93-DC-016
Study First Received: June 19, 2006
Last Updated: April 26, 2014
Health Authority: United States: Federal Government

Keywords provided by National Institutes of Health Clinical Center (CC):
Linkage Analysis

Additional relevant MeSH terms:
Hearing Loss
Ear Diseases
Hearing Disorders
Nervous System Diseases
Neurologic Manifestations
Otorhinolaryngologic Diseases
Sensation Disorders
Signs and Symptoms processed this record on October 21, 2014