Efforts to increase organ donation among Native
Americans may get a boost from research by Johns Hopkins
scientists that is identifying the specific genetic makeup
of the HLA system of human transplantation antigens among
different Indian tribes. HLAs, or human leukocyte antigens,
are proteins on the surface of white blood cells and are
used to determine the suitability of a match between an
organ donor and recipient.
The Native American population has one of the greatest
needs for organ donors because of a high incidence of
diabetes and end-stage renal disease, yet many are
reluctant to donate a kidney because of a belief that they
need to take their body intact to the spiritual world when
they die. If they donate, many believe, their spirit will
be restless.
Researchers with the
Johns Hopkins
Immunogenetics Laboratory say that characterizing the
specific HLA genes among different Indian tribes will
identify their similarities and differences with other
populations, helping to ensure compatible organ
transplants. Their new report, published in the January
issue of the journal Human Immunology, identifies two new
alleles, or alternate gene forms, among the Lakota Sioux
tribe.
"Because so many Native Americans volunteered to be in
this study, we hope that their awareness of the value of
tissue compatibility may make the message of donation more
welcome," said Mary S. Leffell, lead study author and
professor and director of the Hopkins laboratory. "Our
study provides the first look at the HLA proteins and
alleles present among the Sioux people at a time when their
need for transplantation is rapidly increasing. The
findings show that there is a much higher probability of
finding a really good organ match among other Native
Americans than among other racial/ethnic groups," she said.
"Certain Asian populations share some of the same HLA
proteins as the Sioux and also could be good donor
choices."
For the study, the research team looked at two tribes
of the Lakota Sioux — the Cheyenne River and the
Ogala Sioux — residing on the Cheyenne River and Pine
Ridge reservations in South Dakota. Pine Ridge is in the
southwest corner of the state, close to the Badlands, while
the Cheyenne River reservation is located in the north
central part of the state along the Missouri River. These
reservations cover some of the poorest counties in the
nation, with an unemployment rate of more than 80 percent
in some areas and many people living below the federal
poverty level. The Sioux have one of the fastest growing
rates of type 2 diabetes in the United States, Leffell
said.
"The rate of end-stage renal disease among Native
American tribes is from 3.5 to 20 times that of Caucasian
or other populations," she said. "Despite the alarming
growth in kidney disease, kidney transplant as an option
has not increased proportionately."
Leffell and colleagues analyzed blood samples that had
been collected from 302 Lakota Sioux volunteers. Of the
participants, 263 (87 percent) claimed full American Indian
ancestry through both maternal and paternal grandparents.
The study group included 25 nuclear families. The research
was conducted after obtaining resolutions of support from
the Tribal Councils and approval from the Aberdeen Area
Institutional Review Board of the Indian Health Service.
The researchers found several alleles at high
frequency among the Lakota Sioux that also are prevalent in
other Native Americans and Alaskans. They found another
allele that previously had been described only in the
Navajo and Tlingit tribes, as well as two new alleles
observed only among the Sioux. In addition, the team
identified among the Sioux the two most common extended
haplotypes, or groups of alleles thought to be inherited
together.
One of the immediate clinical applications of their
research, Leffell said, is an estimation of the likelihood
of finding unrelated compatible donors for transplantation.
Among the Lakota Sioux, 85 percent had HLA types that
appeared unique; therefore, the remaining 15 percent could
expect to find an exact match among potential organ donors
within their population.
"Native Americans have higher compatibility compared
to other populations, and it should be easier to find a
match within their own group," Leffell said. "We hope this
knowledge will remove some barriers to donation within the
tribes."
The study was conducted as part of a series of
workshops initiated in 1992 by members of the American
Society for Histocompatibility and Immunogenetics to
provide a thorough characterization of the immunogenetics
among minority populations. It was funded in part by the
National Institute of Allergy and Infectious Diseases.
Study co-authors were M. Daniele Fallin, Brian A. Iglehart
and Andrea A. Zachary, all of Johns Hopkins; and Wil-liam
H. Hildebrand and Joshua W. Cavett, both of the University
of Oklahoma.