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HAM/TSP in relatives of HAM/TSP cases and in relatives of asymptomatic HTLV-1 carriers

To assess the hypothesis that HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) runs in families, we compared the frequency of HAM/TSP among HTLV-1-positive relatives of HAM/TSP patients with the frequency of HAM/TSP among HTLV-1-positive relatives of asymptomatic HTLV-1 carriers. We reviewed available information at the Instituto de Medicina Tropical Alexander von Humboldt in Lima (period 1990-2012). Index cases with HAM/TSP were defined as unrelated, HTLV-1-positive patients with a clinical diagnosis of HAM/TSP for whom HAM/TSP was the motive for HTLV-1 testing and who brought ≥1 relative (blood relatives and/or partners) for HTLV-1 testing. Asymptomatic index cases were defined as unrelated, asymptomatic HTLV-1 carriers who were tested for HTLV-1 as candidate blood donors and brought ≥1 relative for screening. In the family studies of 334 index cases with HAM/TSP, 1124 relatives were tested, 318/1124 (28%) were HTLV-1 positive, and 30/318 (9%) had HAM/TSP. In the family studies of 230 asymptomatic index cases, 544 relatives were tested, 204/544 (38%) were HTLV-1 positive, and 15/204 (7%) had HAM/TSP. We classified the relatives in groups based on sex and age. HAM/TSP frequency increased with age and was higher in women than in men. We found no significant differences in HAM/TSP frequency between relatives of HAM/TSP index cases and relatives of asymptomatic index cases. In total, there were 21 families with 2 HAM/TSP cases, 4 families with 3 HAM/TSP cases, and 1 family with 5 HAM/TSP cases. This analysis approach suggests that HAM/TSP usually affects isolated people, but that in some, particular families, HAM/TSP clusters can occur.

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Correspondence to Carolina Alvarez.

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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.

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Alvarez, C., Verdonck, K., Tipismana, M. et al. HAM/TSP in relatives of HAM/TSP cases and in relatives of asymptomatic HTLV-1 carriers. Retrovirology 11 (Suppl 1), P37 (2014).

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