55º Congresso Brasileiro de Genética
Resumos do 55º Congresso Brasileiro de Genética • 30 de agosto a 02 de setembro de 2009
Centro de Convenções do Hotel Monte Real Resort • Águas de Lindóia • SP • Brasil
www.sbg.org.br - ISBN 978-85-89109-06-2
85
Allelic frequencies of HLA-A*, -B* and -DRB1* genes in a
sample of women with recurrent spontaneous abortion
Silva, FF2; Sadalla, LFCR2; Patricio, FJB2; Santos, A2; Santos, AM3; Brito, LMO4; Chein, MBC4, Freire, GIM6;
Martins, MG5; Leal-Mesquita, ER1
Departamento de Biologia da UFMA; Laboratório de Estudos Genômicos e de Histocompatibilidade (LEGH), HUUFMA; Centro de
Pesquisa Clinica (CEPC), HUUFMA. 2Laboratório de Estudos Genômicos e de Histocompatibilidade (LEGH), HUUFMA. 3Departamento
de Saúde Pública da UFMA; Centro de Pesquisa Clinica (CEPC), HUUFMA. 4Departamento de Medicina III da UFMA; Programa de
Pós-Graduação em Saúde Materno Infantil da UFMA. 5Departamento de Medicina III da UFMA; Serviço de Ginecologia e Obstetrícia do
Hospital Universitário – Unidade Materno Infantil (HU-UMI-UFMA). 6Serviço de Ginecologia da Unidade de Saúde José Carlos Macieira
[email protected]; [email protected]
1
Keywords: Abortion, RSA, HLA gene, allelic frequencies, Immunology
Recurrent spontaneous abortion (RSA) is defined as three or more consecutive spontaneous pregnancy losses
before the 20th week of gestation, a situation that that occurs in 1 to 2% of women of reproductive age. Genetic,
anatomical, endocrine, infectious and immunological factors, through mechanisms that relate to the Major
Histocompatibility Complex (MHC) and the presence of certain HLA (Human Leukocyte Antigens) are associated
to RSA. The HLA gene is located on the short arm of chromosome 6, is inherited as a haplotype and expressed in
co-dominance. The basic function of HLA molecules is to promote the recognition of antigens by T lymphocytes
and is also important in the modulation and induction of maternal tolerance during pregnancy. The aim of this
study was to compare the allelic frequencies of loci HLA-A*, HLA-B* and HLA-DRB1* in women that undergo or
not RSA. The research was approved by the Ethics Committee of HUUFMA. We examined 200 women (100 for
each group) between 18 and 35 years of age. All samples were typified by the PCR-SSO method (PCR-Sequence
Specific oligonucleotides). The most frequent alleles observed in the group of women with RSA were: HLA-A*02
(56%), *01 (18%), *30 and *31 (14%); HLA-B*: *15 (32%), *35 and *51 (16%), *40 (15%); HLA-DRB1*: *13 (31%), *04
(26%), *07 (24%). In the sample of women without RSA, the most frequent alleles were: HLA-A*: *02 (49%), *24
(25%), *01 (16%); HLA-B *: *35 (41%), *15 (30%), 51 (13%); HLA-DRB1*: *13 (39%), *11 (26%), *01 (23%). Studies
show that the HLA-A*02 may contribute to maternal immune responses both in normal pregnancies and in the
RSA. The significantly lower frequency of HLA-B35 in patients with unexplained recurrent abortion in some studies
suggests that the Th2-associated immune reactions may be lacking in such patients, as it has been reported that an
enhanced Th2 response in conjunction with a decreased Th1 response is a common immune reaction in HLA-B35positive individuals. In studies related to HLA-DRB1*, some authors found an association between RSA and alleles
* 01 and *03, other authors found this association only for the * 03 allele, which was not found in this study. Further
genetic epidemiology research, including studies that relate to other HLA genes like HLA-G, is indispensable to
clarify the role of HLA antigens and/or its connection to other genes as a risk factor for RSA.
Financial Support: FAPEMA