NHANES III Genetic Data
Collection
of DNA in NHANES III
Description
of the Genetic Data Sets
Demographic
Information
Available
Genetic Data Sets
How
to Access the Restricted Data Sets
How
to Access the Anonymized Data Sets
Informed
Consent
Contact
Us
Collection of DNA in
NHANES III
The National Health and Nutrition
Examination Survey (NHANES) is a program of periodic surveys
conducted by the National Center for Health Statistics (NCHS) of the
Centers for Disease Control and Prevention (CDC). Examination
surveys conducted since 1960 by NCHS have provided national
estimates of the health and nutritional status of the U.S. civilian
non-institutionalized population. To add to the large amount of
information collected for the purpose of describing the health of
the population, blood lymphocytes were collected in NHANES III in
anticipation of advances in genetic research from participants aged
12 years and older and stored in liquid nitrogen as cell cultures
immortalized with Epstein-Barr virus. DNA in the form of crude cell
lysates was made available for approved research projects from
phase-2 (1991-1994) participants. There have been three
announcements for use of these specimens announced (Tuesday, June 1,
1999 [64 FR 29321] August 8, 2002 [67FR 51585] and January 13,
2006[71FR 2248]). Genetic data generated by these projects is
submitted to the NCHS where they are stored upon successful
completion of a three part quality control analysis.
The goals of NHANES are (1) to
estimate the number and percentage of people in the U.S. population
and designated subgroups with selected diseases and risk factors for
those diseases; (2) to monitor trends in the prevalence, awareness,
treatment and control of selected diseases; (3) to monitor trends in
risk behaviors and environmental exposures; (4) to analyze risk
factors for selected diseases; (5) to study the relation among diet,
nutrition and health; (6) to explore emerging public health issues
and new technologies; (7) to establish and maintain a national
probability sample of baseline information on health and nutritional
status.
The Third National Health and
Nutrition Examination Survey (NHANES III) began in the Fall of 1988
and ended in the Fall of 1994. Survey data were collected and can be
analyzed from two phases: Phase-1 was conducted from October, 1988
to October, 1991, and Phase-2 was conducted from October, 1991 to
October, 1994. Both phases are nationally representative samples.
Please reference our
Analytic and Reporting Guidelines for details
on the NHANES III survey design and analytic guidelines. Genetic
data is only available for Phase-2 of this survey.
Description of the
Genetic Data Sets
The genetic
data available through the NCHS is from 7159 specimens collected
during Phase-2 of the
Third National Health and
Nutrition Examination Survey (NHANES III). Linkage of
the NHANES III phenotype data with this genetic information provides
the opportunity to conduct a vast array of outcome studies designed
to investigate the association of a wide variety of health factors
with regard to genetic variation. This collection is an ongoing
process and additional genetic variation information will become
available every six months. The NHANES III genetic data sets contain
information from laboratories that have analyzed DNA in the cell
lysates derived from these participants. The majority of the data
sets will be found in the category of restricted access although
there are a small number of anonymized data sets.
Demographic Information
The NHANES III survey oversampled
non-Hispanic Blacks and Mexican-Americans which yielded the
following population frequencies for the samples used to generate
the genetic data:
Race-Ethnicity |
Frequency |
Non-Hispanic White |
2630 |
Non-Hispanic Black |
2108 |
Mexican-American |
2073 |
Other* |
348 |
Total |
7159 |
|
*The ‘Other’
category includes all Hispanics, regardless of race, who were not
Mexican-American and also includes all non-Hispanics from racial
groups other than white or black.
Available Genetic Data Sets
There are two classifications of
NHANES III genetic data. Please click one of the links below to view
the available data sets for either
restricted or
anonymized data.
Restricted Access
Genetic Data Sets
Requires
IRB approval of analysis proposal.
Linkable
to most NHANES variables for analysis in our secure Research Data
Center (RDC).
Currently,
all analyses must be performed at our RDC at the National Center for
Health Statistics in Hyattsville, MD. There is a fee for the use of
this facility.
Anonymized Genetic Data Sets
Limited
number of associated variables that have been anonymized so the data
can no longer be linked to the public use files and therefore not
linkable to other NHANES data.
Does
not require IRB approval.
Does
not require data analysis at the NCHS.
Data
available upon request with a data use agreement.
How to Access the
Restricted Data Sets
Proposals to analyze genetic data sets
may be submitted to
NHANESGenetics@CDC.gov. Proposals will be reviewed three
times annually by our IRB. Submissions for secondary data analysis
of restricted data sets are accepted in February, June and October.
For additional information on submission guidelines, please see our
Guidelines for Secondary Data Analysis of NHANES III
Genetic Data.
How to Access the
Anonymized Data Sets
Access to the anonymized data sets
does not require IRB approval because they are no longer linkable to
any other data sets. These data sets contain a set number of
variables. For access to genetic data in this category, please
contact us at
NHANESGenetics@CDC.gov.
Informed
Consent
Health information collected in the
NHANES III is kept in strictest confidence. During the informed
consent process, survey participants are assured that data collected
will be used only for stated purposes and will not be disclosed or
released to others without the consent of the individual or the
establishment in accordance with section 308(d) of the Public Health
Service Act (42 U.S.C. 242m). Although the consent form was signed
by participants in the survey, and participants consented to storing
specimens of their blood for future research, specific mention of
genetic research was not included during NHANES III. Nevertheless,
given the scientific importance of this resource, the CDC/NCHS
Ethics Review Board (ERB) initially approved use of the DNA only if
the samples were anonymized. The anonymization requirements proved
to be restrictive and difficult to implement, therefore, in August,
2001 the CDC/NCHS ERB approved a revised plan for using these
specimens based on the guidelines in the August, 1999 National
Bioethics Advisory Commission (NBAC) report on the use of stored
biological materials for research. This revised plan included a
process that gives researchers the ability to obtain more
information associated with specimens for protocols that are
determined by the ERB to have minimal risk for harm to the
participant. For those protocols that cannot be conducted under
unlinked (or anonymous) conditions, but have been determined to
involve minimal risk, the revised plan allowed for linking of the
genetic laboratory results to the NHANES data through the NCHS
Research Data Center. This process ensured that confidentiality of
the subjects’ identity was maintained.
Contact Us
Please contact
NHANESGenetics@CDC.gov
with any questions regarding NHANES genetic data.
|