Allelic frequencies of eight autosomal short-tandem repeat (STR) loci (TH01, TPOx, CSF1PO, vWA, FES/FPS, F13A1, F13B, and CD4) were determined in 400 individuals born in the State of São Paulo. No significant deviations from Hardy-Weinberg equilibrium were found in any loci analyzed. The Unweighted Pair-Group Method with Arithmetic Mean (UPGMA) tree constructed based on genetic distances revealed that the present population was grouped with Europeans, and separated from African and Amerindian populations. Estimates of admixture components based on the gene identity method revealed 79% European, 14% African, and 7% Amerindian contributions to this Brazilian population sample.

BackgroundNeuromyelitis optica (NMO) is considered relatively more common in non-Whites, whereas multiple sclerosis (MS) presents a high prevalence rate, particularly in Whites from Western countries populations. However, no study has used ancestry informative markers (AIMs) to estimate the genetic ancestry contribution to NMO patients.MethodsTwelve AIMs were selected based on the large allele frequency differences among European, African, and Amerindian populations, in order to investigate the genetic contribution of each ancestral group in 236 patients with MS and NMO, diagnosed using the McDonald and Wingerchuck criteria, respectively. All 128 MS patients were recruited at the Faculty of Medicine of Ribeirão Preto (MS-RP), Southeastern Brazil, as well as 108 healthy bone marrow donors considered as healthy controls. A total of 108 NMO patients were recruited from five Neurology centers from different Brazilian regions, including Ribeirão Preto (NMO-RP).Principal FindingsEuropean ancestry contribution was higher in MS-RP than in NMO-RP (78.5% vs. 68.7%) patients. In contrast, African ancestry estimates were higher in NMO-RP than in MS-RP (20.5% vs. 12.5%) patients. Moreover, principal component analyses showed that groups of NMO patients from different Brazilian regions were clustered close to the European ancestral population.ConclusionsOur findings demonstrate that European genetic contribution predominates in NMO and MS patients from Brazil.

Brazil is the result of interethnic crosses of European, African and Amerindian populations. Allelic frequencies for seven STR loci (TH01, TPOx, CSF1PO, vWA, FES/FPS, F13A1 and CD4), obtained from a sample of 70 individuals identified as Afro-Brazilian and 150 as mulatto, are presented here. Based on the frequencies of these genetic markers, estimates of interethnic admixture showed 62%, 26% and 12% of European, African and Amerindian contribution, respectively, for the mulatto sample and 37% and 63% of European and African contribution, respectively, for the Afro-Brazilian sample.