Absence of HLA-DQ2 and HLA-DQ8 does not exclude celiac disease in Brazilian patients
La ausencia de HLA-DQ2 y HLA-DQ8 no excluye la enfermedad celiaca en pacientes brasileños
Key words: Celiac disease. HLA. Brazilian population. HLA-DQ2 antigen. HLA DQ-8 antigen.
Dear Editor,
]]> The genetic predisposition is well known in celiac disease (CD). In a recent review, Vives et al. (1) related that about 90 % of CD patients expressed HLA-DQ2, and 5 % of them have the HLA-DQ8. The remaining 5 % of CD patients have one of the two genes that form the HLA-DQ2 heterodimer but do not present the full heterodimer. HLA-related genes are necessary but not sufficient to cause the disease. On the other hand, HLA class II DQ2 and DQ8 are responsible for approximately 40 % of genetic risk to CD. Also, their absence has a high negative predictive value and, in the clinical practice, could exclude a diagnosis of CD (1,2). However, is it really true for a population with a high admixture of races as Brazilian population?The present study investigated CD patients from Southern Brazilian population, which was researched HLA-DQ2 and HLA-DQ8 alleles. A total of 101 consecutive patients, composed of 83 female and 18 male subjects, with median age of 30 years (rank: 3 to 87 years), all auto-declared with European ascendance, were evaluated and were diagnosed using positive serological tests (IgA antiendomysium) and confirmed using histological findings in duodenal biopsies (Marsh classification). HLA-DQ2 and HLA-DQ8 presence was typed using DNA amplified by polymerase chain reaction. The presence of HLA-DQ2 was observed in 80 (79.2 %) of the 101 celiac patients and HLA-DQ8 in 26 (25.7 %). In 101 cases, HLA-DQ2 and HLA-DQ8 were concomitantly detected in 14 (13.9 %), HLA-DQ2 positive was found in 66 (65.3 %), and HLA-DQ8 positive was observed in 12 (11.9 %). Nine patients (8.9 %) did not present HLA-DQ2 and/or HLA-DQ8 positive. All these cases, in spite of HLA-DQ2 HLA-DQ8 being both negative, had clinical evidence, positive serology, and confirmed CD diagnosis after duodenal biopsies. Besides, recovery was documented after following a gluten-free diet-based treatment. Martins et al. (3) investigating 90 Brazilian celiac patients in Brasilia (Mild West Region) showed that with one exception (1.1 %), all the patients carried DQ2 and/or DQ8 alleles. Castro-Nunes et al. (4), studying 73 patients with CD from Northeastern Brazil, described 50 (68.5 %) with genotype DQ2, 13 (17.8 %) with DQ8, five (6.8 %) with DQ2 and DQ8 concomitantly, and five (6.8 %) without any of these genotypes. Similar observations have been reported from European (5) and American populations (6). Latin American celiac patients (Argentina, Chile and Uruguay) also showed 7 % of negative results for DQ2 and/or DQ8 in a multicenter report (7).
Concluding, in the present study, HLA-DQ2 and HLA-DQ8 were detected in most CD patients, corroborating the literature reports, although in minor percentage. However, the finding of 8.9 % of diagnosed CD patients negative for HLA-DQ2 and/or HLA-DQ8 alleles emphasizes that in a high admixture population, such as the Brazilian population, even in individuals with European ascendancy, the absence of these markers does not exclude CD.
Lorete Maria da Silva Kotze1, Renato Nisihara2, Shirley Ramos da Rosa Utiyama3 and Luiz Roberto Kotze1
1Service of Gastroenterology. Cajuru Hospital. Pontifical Catholic University of Paraná.
2Department of Medicine. Positivo University.
3Laboratory of Immunopathology. Clinical Hospital. Federal University of Paraná
Curitiba-Paraná, Brazil
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