Clinical Trial: Non-Syndrome Hereditary Hearing Impairment - Gene Mapping: India/Pakistan Protocol
Study Status: Recruiting
Recruit Status: Recruiting
Study Type: Observational
Official Title: Non-Syndromic Hereditary Hearing Impairment - Gene Mapping: India/Pakistan Protocol
Brief Summary:
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.
Detailed Summary:
Objective: One objective of this study is to genetically map and identify mutated genes for human hereditary hearing loss. A second objective is to study the function of these genes in the auditory system using mouse models. Human hereditary hearing impairment is the result of abnormal ear development, abnormal ear function or both. Although the genes for numerous deafness loci have been mapped and identified, there are still many families segregating deafness as a monogenic trait but a mutant allele can t be ascribed to one of the currently reported deafness genes . In order to map and identify novel mutated genes associated with hearing loss in humans, we will continue to ascertain large families segregating syndromic and nonsyndromic deafness as a monogenic trait.
Study population: This study will ascertain subjects from consanguineous Pakistani families segregating hearing loss consisting of both nonsyndromic and syndromic forms of deafness of genetic etiology. Since a majority of Pakistani marriages are between first cousins, this tends to bring together the same recessive mutations for hearing loss with multiple affected individuals within single family lines, which is an advantage for this genetic study. A few years ago we stopped ascertaining families in India. We continue to ascertain both affected and unaffected Pakistani family members from age 2 years and up. Adults provide informed consent both for themselves and their children who agree to participate in this study. We will ascertain both genders and all Pakistani races and ethnicities.
Design: Subjects will be screened and consented by our collaborating Associate Investigator in Pakistan. After consenting, the subjects will undergo a history and physical, audiological assessment and testing, vestibular assessment and testing, and blood and urine analysis tes
Sponsor: National Institute on Deafness and Other Communication Disorders (NIDCD)
Current Primary Outcome: New genes and loci associated with hearing loss will be identified and new strategies to prevent and preserve hearing will be developed [ Time Frame: 07/01/2020 ]
Original Primary Outcome:
Current Secondary Outcome:
Original Secondary Outcome:
Information By: National Institutes of Health Clinical Center (CC)
Dates:
Date Received: June 19, 2006
Date Started: July 15, 1992
Date Completion:
Last Updated: April 21, 2017
Last Verified: February 28, 2017
