How many populations set foot through the Patagonian door? Genetic composition of the current population of Bahía Blanca (Argentina) based on data from 19 Alu polymorphisms

The city of Bahía Blanca occupies a strategic place in Argentina south of the Pampean region in the north-east corner of the Patagonia. Since 1828, this city has been the historical and political border between Amerindian lands in the south, and the lands of European colonists. Nowadays, Bahía Blanca is an urban population mainly composed by descendents of immigrants from Spain and other European countries with apparently low admixture with Amerindians. In view of the unexpectedly high Amerindian admixture levels (about 46.7%) suggested by mtDNA data, and protein markers (19.5%), we analyzed a set of 19 Alu polymorphisms (18 autosomal, 1 of Chromosome Y) in a well-documented genealogical sample from Bahía Blanca. The genotyped sample was made up of 119 unrelated healthy individuals whose birth place and grandparent origins were fully documented. According to available genealogical records, the total sample has been subdivided into two groups: Bahía Blanca Original (64 individuals with all 4 gandparents born in Argentina) and Bahía Blanca Mix (55 individuals with one to three grandparents born out of Argentina). Allele frequencies and gene diversity values in Bahía Blanca fit well into the European ranges. Population relationships have been tested for 8 Alu markers, whose variation has been described in several Amerindian and European samples. Reynolds genetic distances underline the significant genetic similarity of Bahía Blanca to Europeans (mean distance 0.044) and their differentiation from Amerindians (0.146). Interestingly enough, when the general sample is divided, Bahía Blanca Original appears slightly closer to Amerindians (0.127) in contrast to Bahía Blanca Mix (0.161). Furthermore, the genetic relationships depicted through a principal components analysis emphasize the relative similarity of Bahía Blanca Original to Amerindians. A thorough knowledge of the sample origins has allowed us to make a subtle distinction of the genetic composition of Bahía Blanca.

Subcutaneous alemtuzumab in patients with refractory/relapsed B-CLL after a fludarabine-based regimen

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Background: Alemtuzumab is the only immunotherapy that is effective as a single agent in patients with B-CLL who are refractory to, or who have relapsed after, fludarabine therapy. The optimized schedule for alemtuzumab that achieves maximal efficacy with manageable toxicity is still being explored. We report the first interim analysis of a new, less intensive schedule of alemtuzumab SC to patients with refractory/relapsed B-CLL. Methods: Alemtuzumab was dose escalated from 10 to 20 mg during the first week, 30 mg bid during the second and third weeks, and 30 mg once weekly during weeks 4, 6, 8, 10, 12, 16, 20, 24, 28, 34, and 40. Antiviral prophylaxis included TMP/SMX bid 3 times a week and acyclovir 200 mg tid. Results: Patients (N = 36) with refractory (19%) or relapsed (81%) B-CLL had a median age of 67 years (range, 43–86 years), 28 were male, 61%/39% had Binet stage B/C disease, and 2 had B-cell prolymphocytic transformation. The median number of prior therapies was 1 (range, 1–4). The median duration of treatment was 7 weeks (range, 2–24 weeks), with a median cumulative alemtuzumab dose of 412 mg (range, 150–1,080 mg). Thirty-two patients were evaluable for response. The overall response rate of 93%: complete response (CR), 34%; unconfirmed CR, 6%; partial response (PR), 53%. Two patients (7%) did not respond to therapy. Of the 7 refractory patients, 5 had a PR, 1 did not respond, and 1 was not yet evaluable. Median overall survival was 10 months, which correlated with response and pretreatment status. Minimal residual disease (MRD) was measured by flow cytometry in 5 patients who achieved a CR: 3 patients had <0.5% of CD5/CD19/CD23+ cells, 1 patient had <5% of CLL cells, and 1 patient had <10% CLL cells. According to WHO toxicity criteria, 5 patients experienced grade 3/4 infection; 2 patients had grade 3 granulocytopenia/thrombocytopenia; 1 patient had cytomegalovirus (CMV) reactivation without CMV disease; and 1 patient developed Epstein-Barr Virus with prolonged bone marrow hypoplasia. Conclusions: Results of this interim analysis suggest that a less intense regimen of alemtuzumab is feasible, effective, and safe for patients with refractory/relapse B-CLL after fludarabine therapy.

No significant financial relationships to disclose.