DNA databases of an important tropical timber tree species Shorea leprosula (Dipterocarpaceae) for forensic timber identification.

International timber trade communities are increasingly demanding that timber in the wood supply chain be sourced from sustainably harvested forests and certified plantations. This is to combat illegal logging activities to prevent further depletion of our precious forests worldwide. Hence, timber tracking tools are important to support law enforcement officials in ensuring only sustainably harvested timbers are traded in the market. In this study, we developed chloroplast DNA (cpDNA) and simple sequence repeat (SSR) databases as tracking tools for an important tropical timber tree species, Shorea leprosula from Peninsular Malaysia. A total of 1410 individual trees were sampled from 44 natural populations throughout Peninsular Malaysia. Four cpDNA regions were used to generate a cpDNA haplotype database, resulting in a haplotype map comprising 22 unique haplotypes derived from 28 informative intraspecific variable sites. This cpDNA database can be used to trace the origin of an unknown log at the regional level. Ten SSR loci were used to develop the SSR allele frequency database. Bayesian cluster analysis divided the 44 populations into two genetic clusters corresponding to Region A and Region B. Based on conservativeness evaluation of the SSR databases for individual identification, the coancestry coefficients (θ) were adjusted to 0.1900 and 0.1500 for Region A and B, respectively. These databases are useful tools to complement existing timber tracking systems in ensuring only legally sourced timbers are allowed to enter the wood supply chain.

Multiple strain infection of Mycobacterium leprae in a family having 4 patients: A study employing short tandem repeats.

BACKGROUND: Leprosy is a slow, chronic disorder caused by Mycobacterium leprae. India has achieved elimination of leprosy in December 2005 but new cases are being detected and continue to occur in some endemic pockets. The possible ways of transmission of leprosy is not fully understood and is believed that leprosy is transmitted from person to person in long term contact. Studying the transmission dynamics is further complicated by inability to grow M. leprae in culture medium and lack of animal models. More than one family members were found to be affected by leprosy in some highly endemic pockets. This study reported the transmission pattern of leprosy in a family having 4 patients. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the transmission of leprosy in a single family having 4 patients using microsatellite typing. DNA was isolated from slit skin smear samples taken from the patients and the isolated DNA were amplified using microsatellite loci TA11CA3. The amplified products were sequenced using Sanger's sequencing methods and the copy number variation in the microsatellite loci between strains were elucidated by multiple sequence alignment. The result showed that all the 4 members of the family acquired infection from 3 different strains of M. leprae from 3 different sources. The elder and middle daughters were infected by same types of strains having the repeat unit TA13CA3 and could have acquired the infection from social contacts of leprosy cases while the father and younger daughter were infected by strains with the repeat unit TA12CA3 and TA11CA3 and could have acquired infection from social contacts. CONCLUSIONS/SIGNIFICANCE: The study suggested that three family members viz, elder daughter, father and younger daughter could be infected by M. leprae from 3 different sources and the history of the disease and genetic analysis showed that the middle daughter acquired infection from her elder sister in due course of contact. This study implies that the transmission of leprosy not only occurred amongst the house hold members but also has been transmitted from social and neighborhood contacts in long term association with the them.

Are patterns of fine-scale spatial genetic structure consistent between sites within tropical tree species?

Documenting the scale and intensity of fine-scale spatial genetic structure (FSGS), and the processes that shape it, is relevant to the sustainable management of genetic resources in timber tree species, particularly where logging or fragmentation might disrupt gene flow. In this study we assessed patterns of FSGS in three species of Dipterocarpaceae (Parashorea tomentella, Shorea leprosula and Shorea parvifolia) across four different tropical rain forests in Malaysia using nuclear microsatellite markers. Topographic heterogeneity varied across the sites. We hypothesised that forests with high topographic heterogeneity would display increased FSGS among the adult populations driven by habitat associations. This hypothesis was not supported for S. leprosula and S. parvifolia which displayed little variation in the intensity and scale of FSGS between sites despite substantial variation in topographic heterogeneity. Conversely, the intensity of FSGS for P. tomentella was greater at a more topographically heterogeneous than a homogeneous site, and a significant difference in the overall pattern of FSGS was detected between sites for this species. These results suggest that local patterns of FSGS may in some species be shaped by habitat heterogeneity in addition to limited gene flow by pollen and seed dispersal. Site factors can therefore contribute to the development of FSGS. Confirming consistency in species' FSGS amongst sites is an important step in managing timber tree genetic diversity as it provides confidence that species specific management recommendations based on species reproductive traits can be applied across a species' range. Forest managers should take into account the interaction between reproductive traits and site characteristics, its consequences for maintaining forest genetic resources and how this might influence natural regeneration across species if management is to be sustainable.

Association between STR -794 CATT5-8 and SNP -173 G/C polymorphisms in the MIF gene and Lepromatous Leprosy in Mestizo patients of western Mexico.

Lepromatous Leprosy (LL) is the most common presentation of leprosy in Mexico. LL patients are unable to activate an effective inflammatory response against Mycobacterium leprae probably due to the genetics of the host. Macrophage Migration Inhibitory Factor (MIF) is important to trigger inflammation processes. Two polymorphisms have been reported for human MIF: STR -794 CATT5-8 and SNP -173 G/C. 7-8 CATT repeats at -794 and the C allele at -173 increase the expression of MIF. We aim to determine the association between the polymorphisms in MIF gene and LL. We carried a case and controls study with 100 Mexican LL patients and 100 healthy subjects (HS). PCR was used for genotyping of STR -794 CATT5-8 polymorphism and PCR-RFLP for -173 G/C. We found that LL patients possess high -794 CATT repeats (47.1%) more often than HS (32.7%). In conclusion, a MIF polymorphism is associated with susceptibility to LL in Western Mexican population.

Genotyping of Mycobacterium leprae strains from a region of high endemic leprosy prevalence in India.

Leprosy is still a major health problem in India which has the highest number of cases. Multiple locus variable number of tandem repeat analysis (MLVA) and single nucleotide polymorphism (SNP) have been proposed as tools of strain typing for tracking the transmission of leprosy. However, empirical data for a defined population from scale and duration were lacking for studying the transmission chain of leprosy. Seventy slit skin scrapings were collected from Purulia (West Bengal), Miraj (Maharashtra), Shahdara (Delhi), and Naini (UP) hospitals of The Leprosy Mission (TLM). SNP subtyping and MLVA on 10 VNTR loci were applied for the strain typing of Mycobacterium leprae. Along with the strain typing conventional epidemiological investigation was also performed to trace the transmission chain. In addition, phylogenetic analysis was done on variable number of tandem repeat (VNTR) data sets using sequence type analysis and recombinational tests (START) software. START software performs analyses to aid in the investigation of bacterial population structure using multilocus sequence data. These analyses include data summary, lineage assignment, and tests for recombination and selection. Diversity was observed in the cross-sectional survey of isolates obtained from 70 patients. Similarity in fingerprinting profiles observed in specimens of cases from the same family or neighborhood locations indicated a possible common source of infection. The data suggest that these VNTRs including subtyping of SNPs can be used to study the sources and transmission chain in leprosy, which could be very important in monitoring of the disease dynamics in high endemic foci. The present study strongly indicates that multi-case families might constitute epidemic foci and the main source of M. leprae in villages, causing the predominant strain or cluster infection leading to the spread of leprosy in the community.

A historical overview of leprosy epidemiology and control activities in Amazonas, Brazil

Leprosy is an ancient infectious disease caused by Mycobacterium leprae. According to comparative genomics studies, this disease originated in Eastern Africa or the Near East and spread with successive human migrations. The Europeans and North Africans introduced leprosy into West Africa and the Americas within the past 500 years. In Brazil, this disease arrived with the colonizers who disembarked at the first colonies, Rio de Janeiro, Salvador and Recife, at the end of the sixteenth century, after which it was spread to the other states. In 1854, the first leprosy cases were identified in State of Amazonas in the north of Brazil. The increasing number of leprosy cases and the need for treatment and disease control led to the creation of places to isolate patients, known as leprosaria. One of them, Colonia Antônio Aleixo was built in Amazonas in 1956 according to the most advanced recommendations for isolation at that time and was deactivated in 1979. The history of the Alfredo da Matta Center (AMC), which was the first leprosy dispensary created in 1955, parallels the history of leprosy in the state. Over the years, the AMC has become one of the best training centers for leprosy, general dermatology and sexually transmitted diseases in Brazil. In addition to being responsible for leprosy control programs in the state, the AMC has carried out training programs on leprosy diagnosis and treatment for health professionals in Manaus and other municipalities of the state, aiming to increase the coverage of leprosy control activities. This paper provides a historical overview of leprosy in State of Amazonas, which is an endemic state in Brazil.

IFN-γ +875 microsatellite polymorphism as a potential protection marker for leprosy patients from Amazonas state, Brazil.

Polymorphisms present in the first intron of IFN-γ may have an important role in the regulation of the immune response, which could have functional consequences for gene transcription. Leprosy patients are characterized by different immune responses in different clinical forms. We investigated a possible association of the +874 polymorphism and CA repeats present in the first intron of IFN-γ with susceptibility to leprosy and with the manifestation of the different clinical forms. Nucleotide sequencing was performed with samples from 108 leprosy patients and 113 controls subjects, as well as immunophenotyping of CD(4)(+), CD(8)(+) and CD(69)(+) T cells by flow cytometry. The data showed that there were no significant differences between patients and control subjects, as well as according classification of Ridley-Jopling. However, the A/A genotype was significantly increased in paucibacillary patients (p=0.028) and the microsatellite encoding 16 CA repeats were significantly associated with paucibacillary compared to multibacillary patients (p=0.019). Individuals homozygous for the +874 A allele, the mean level of CD(4)(+) and CD(69)(+) T cells was higher. Our data suggest that polymorphisms present in the first intron of IFN-γ are not associated with susceptibility to leprosy, nevertheless, the +874 polymorphism and the CA repeats number encoded in IFN-γ gene may be related to a higher cellular immune response in patients and are consistently more frequently detected in PB patients.

Comparison between microsatellites and Ml MntH gene as targets to identify Mycobacterium leprae by PCR in leprosy.

BACKGROUND: The Polymerase Chain Reaction (PCR) technique has been frequently used in the molecular diagnosis of leprosy. OBJECTIVES: To compare the results of PCR with four pairs of Mycobacterium leprae specific primers as well as to compare these results to multibacillary (MB) and paucibacillary (PB) leprosy according to the WHO operational classification. METHOD: 28 DNA samples, collected from the frozen skin biopsies and biopsy imprints on filter paper of 23 patients (14 MB and PB 9), were examined for PCR using primers which amplify 131, 151 and 168bp of specific microsatellite regions and a 336 fragment of the Ml MntH (ML2098) gene. RESULTS: M.leprae bacillus could be detected in 22 (78.6%) of the 28 samples. 9 (45%) of the 20 biopsy samples and 6 (75%) of the 8 imprints were positive to TTC. 7 (35.5%) skin biopsy specimens and 5 (62.5%) imprints were positive to AGT, and 11 (55%) biopsies and 4 (50%) were positive to AGT. 11 (55%) skin biopsies and 4 (50%) imprints were positive to AT. 8(38%) skin biopsies and 5 (62.5%) imprints were positive to the Ml MntH gene. In the MB group, the microsatellites detected the bacillus in 78.5% of the samples, and the Ml MntH gene in 57.1% of the samples, independent of the clinical material. In the PB group 55.5% of samples were positive to the microsatellite primers, while 22.2% were positive to the Ml MntH gene. CONCLUSIONS: These results show that both the specific regions of microsatellites, as well as the Ml MntH gene fragment can be useful tools for detecting the M. leprae DNA by PCR in frozen skin biopsy samples and filter paper biopsy imprints.

Comparação entre microssatélites e o gene Ml MntH como alvos para a identificação do Mycobacterium leprae por PCR na hanseníase / Comparison between microsatellites and Ml MntH gene as targets to identify Mycobacterium leprae by PCR in leprosy

FUNDAMENTOS: PCR tem sido frequentemente utilizada no diagnóstico molecular da hanseníase. OBJETIVOS: comparar os resultados da PCR com 4 pares de primers específicos para Mycobacterium leprae, bem como os resultados da PCR à classificação operacional, segundo a OMS, de multibacilar (MB) e paucibacilar (PB) da hanseníase. MÉTODO: Vinte e oito amostras de DNA, extraído de biópsias congeladas de pele e de imprint de biópsias em papel de filtro de 23 pacientes (14 MB e 9 PB), foram utilizadas na PCR com primers que amplificam 131pb, 151pb e 168pb de regiões de microssatélites, e um fragmento de 336pb do gene Ml MntH (ML2098) do bacilo. RESULTADOS: O bacilo pôde ser detectado em 22 (78,6 por cento) das 28 amostras. Nove (45 por cento) das 20 amostras de biópsia e 6 (75 por cento) das 8 amostras de imprints foram positivas para TTC. Sete (35,5 por cento) amostras de biópsias e 5 (62,5 por cento) imprints foram positivos para AGT, e 11 (55 por cento) biópsias e 4 (50 por cento) imprints foram positivos para AT. Oito (38 por cento) amostras de biópsias e 5 (62,5 por cento) imprints foram positivos para o gene Ml MntH. Dentre o grupo MB, os microssatélites detectaram o bacilo em 78,5 por cento das amostras, e o gene Ml MntH, em 57,1 por cento das amostras, independentemente do material clínico. No grupo PB, 55,5 por cento das amostras foram positivas para os microssatélites, enquanto que 22,2 por cento o foram para o gene Ml MntH. CONCLUSÕES: Estes resultados mostram que, tanto as regiões específicas de microssatélites quanto o gene Ml MntH, podem representar ferramentas úteis na detecção do Ml MntH por PCR em amostras de biópsias e imprint de biópsias.

BACKGROUND: The Polymerase Chain Reaction (PCR) technique has been frequently used in the molecular diagnosis of leprosy. OBJECTIVES: To compare the results of PCR with four pairs of Mycobacterium leprae specific primers as well as to compare these results to multibacillary (MB) and paucibacillary (PB) leprosy according to the WHO operational classification. METHOD: 28 DNA samples, collected from the frozen skin biopsies and biopsy imprints on filter paper of 23 patients (14 MB and PB 9), were examined for PCR using primers which amplify 131, 151 and 168bp of specific microsatellite regions and a 336 fragment of the Ml MntH (ML2098) gene. RESULTS: M.leprae bacillus could be detected in 22 (78.6 percent) of the 28 samples. 9 (45 percent) of the 20 biopsy samples and 6 (75 percent) of the 8 imprints were positive to TTC. 7 (35.5 percent) skin biopsy specimens and 5 (62.5 percent) imprints were positive to AGT, and 11 (55 percent) biopsies and 4 (50 percent) were positive to AGT. 11 (55 percent) skin biopsies and 4 (50 percent) imprints were positive to AT. 8(38 percent) skin biopsies and 5 (62.5 percent) imprints were positive to the Ml MntH gene. In the MB group, the microsatellites detected the bacillus in 78.5 percent of the samples, and the Ml MntH gene in 57.1 percent of the samples, independent of the clinical material. In the PB group 55.5 percent of samples were positive to the microsatellite primers, while 22.2 percent were positive to the Ml MntH gene. CONCLUSIONS: These results show that both the specific regions of microsatellites, as well as the Ml MntH gene fragment can be useful tools for detecting the M. leprae DNA by PCR in frozen skin biopsy samples and filter paper biopsy imprints.

Use of short tandem repeat sequences to study Mycobacterium leprae in leprosy patients in Malawi and India.

BACKGROUND: Inadequate understanding of the transmission of Mycobacterium leprae makes it difficult to predict the impact of leprosy control interventions. Genotypic tests that allow tracking of individual bacterial strains would strengthen epidemiological studies and contribute to our understanding of the disease. METHODOLOGY/PRINCIPAL FINDINGS: Genotyping assays based on variation in the copy number of short tandem repeat sequences were applied to biopsies collected in population-based epidemiological studies of leprosy in northern Malawi, and from members of multi-case households in Hyderabad, India. In the Malawi series, considerable genotypic variability was observed between patients, and also within patients, when isolates were collected at different times or from different tissues. Less within-patient variability was observed when isolates were collected from similar tissues at the same time. Less genotypic variability was noted amongst the closely related Indian patients than in the Malawi series. CONCLUSIONS/SIGNIFICANCE: Lineages of M. leprae undergo changes in their pattern of short tandem repeat sequences over time. Genetic divergence is particularly likely between bacilli inhabiting different (e.g., skin and nerve) tissues. Such variability makes short tandem repeat sequences unsuitable as a general tool for population-based strain typing of M. leprae, or for distinguishing relapse from reinfection. Careful use of these markers may provide insights into the development of disease within individuals and for tracking of short transmission chains.

Genome-wide scan for loci influencing quantitative immune response traits in the Belém family study: comparison of methods and summary of results.

Here we report the results from a genome-wide linkage scan to identify genes and chromosomal regions that influence quantitative immune response traits, using multi-case leprosy and tuberculosis families from north-eastern Brazil. Total plasma IgE, antigen-specific IgG to Mycobacterium leprae soluble antigen (MLSA), M. tuberculosis soluble antigen (MTSA) and M. tuberculosis purified protein derivative (PPD), and antigen-specific lymphocyte proliferation (stimulation index or SI) and interferon-gamma (IFN-gamma) release to MLSA and PPD, were measured in 16 tuberculosis (184 individuals) and 21 leprosy (177 individuals) families. The individuals were genotyped at 382 autosomal microsatellite markers across the genome. The adjusted immune-response phenotypes were analysed using a variety of variance components and regression-based methods. These analyses highlighted a number of practical issues and problems with regard to implementation of the methods and, interestingly, differences were observed between several standard statistical and genetic analysis packages used. From this we determined that, for this set of traits in these pedigrees, significant p values for linkage using variance components analysis, supported by significance using the Visscher-Hopper modification of the Haseman-Elston method, provided the most compelling evidence for linkage. Using these criteria, linkage (5.8 x 10(-5) < p < 0.008) was seen for: total plasma IgE on chromosome 2; IgG to MLSA on chromosomes 8, 17 and 21; IgG to PPD on chromosome 12; SI to PPD on chromosome 1; IFN-gamma to MLSA on chromosomes 6, 7, 10, 12 and 14; and IFN-gamma to PPD on chromosomes 1, 16 and 19.

[Geographical races of certain species of ascomycetous yeasts in the Moscow and Novosibirsk regions].

Strains of three species of the ascomycetous yeasts Hanseniaspora guilliermondii, Torulaspora delbrueckii, and Debaryomyces hansenii, isolated from the above-ground parts of plants in similar biocenoses of distant geographic regions (Moscow and Novosibirsk regions), have been investigated. The strains in each species were indistinguishable with respect to phenotypic features and general DNA characteristics as determined by restriction analysis. However, comparison of the strains using PCR analysis with nonspecific primers revealed considerable intraspecific variability. From their electrophoretic patterns, the strains of the three species studied were found to cluster in accordance with the region of isolation. This phenomenon is interpreted as an example of the existence of geographical races in the major eurytopic species of yeasts.

Diversity of potential short tandem repeats in Mycobacterium leprae and application for molecular typing.

A recent advance in molecular typing for tracing the transmission of leprosy is the discovery of short tandem repeats (STRs) in Mycobacterium leprae. To substantiate polymorphic loci from STR as promising candidates for molecular typing tools in leprosy epidemiology, 44 STR loci including 33 microsatellites and 11 minisatellites were investigated among 27 laboratory strains by sequencing PCR products. Not all STRs were necessarily polymorphic. Thirty-two out of the 44 loci were polymorphic. Nine polymorphic loci were suitable for identifying genotypes according to the discriminatory capacity, stability, and reproducibility. All the strains were classified into independent genotypes by the selected nine loci. Three multi-case households were subjected to molecular typing. M. leprae obtained from household cases showed identical copy numbers by TTC triplet alone, but the isolates from one family contact case were divided into different genotypes by adding eight other polymorphic loci. The combination of information from multiple loci allows increasing levels of discrimination and it is likely that the generation and documentation of data will result in the choice of a potential molecular typing tool for leprosy epidemiology.

Microsatellite mapping of Mycobacterium leprae populations in infected humans.

To investigate genetic diversity in a bacterial population, we measured the copy numbers of simple sequence repeats, or microsatellites, in Mycobacterium leprae from patients living in and around Hyderabad, India. Three microsatellite loci containing trinucleotide or dinucleotide repeats were amplified from infected tissues, and the copy numbers were established by sequence analysis. Extensive diversity was observed in a cross-sectional survey of 33 patients, but closely related profiles were found for members of a multicase family likely to share a common transmission source. Sampling of multiple tissues from single individuals demonstrated identical microsatellite profiles in the skin, nasal cavity, and bloodstream but revealed differences at one or more loci for M. leprae present in nerves. Microsatellite mapping of M. leprae represents a useful tool for tracking short transmission chains. Comparison of skin and nerve lesions suggests that the evolution of disease within an individual involves the expansion of multiple distinct subpopulations of M. leprae.

Spatial structure and genetic diversity of two tropical tree species with contrasting breeding systems and different ploidy levels.

Analyses of the spatial distribution pattern, spatial genetic structure and of genetic diversity were carried out in two tropical tree species with contrasting breeding systems and different ploidy levels using a 50-ha demographic plot in a lowland dipterocarp forest in Peninsular Malaysia. Shorea leprosula is a diploid and predominantly outcrossed species, whereas S. ovalis ssp. sericea is an autotetraploid species with apomictic mode of reproduction. Genetic diversity parameters estimated for S. leprosula using microsatellite were consistently higher than using allozyme. In comparisons with S. leprosula and other tropical tree species, S. ovalis ssp. sericea also displayed relatively high levels of genetic diversity. This might be explained by the lower pressure of genetic drift due to tetrasomic inheritance, and for autotetraploids each locus can accommodate up to four different alleles and this allows maintenance of more alleles at individual loci. The observed high levels of genetic diversity in S. ovalis ssp. sericea can also be due to a random retention of more heterogeneous individuals in the past, and the apomictic mode of reproduction might be an evolutionary strategy, which allows the species to maintain high levels of genetic diversity. The spatial distribution pattern analyses of both species showed significant levels of aggregation at small and medium but random distribution at the big diameter-class. The decrease in magnitude of spatial aggregation from small- to large-diameter classes might be due to compensatory mortality during recruitment and survival under competitive thinning process. Spatial genetic structure analyses for both species revealed significant spatial genetic structure for short distances in all the three diameter-classes. The magnitude of spatial genetic structure in both species was observed to be decreasing from smaller- to larger-diameter classes. The high spatial genetic structuring observed in S. ovalis ssp. sericea at the small-diameter class is due primarily to limited seed dispersal and apomictic mode of reproduction. The similar observation in S. leprosula, however, can be explained by limited seed and pollen dispersal, which supports further the fact that the species is pollinated by weak fliers, mainly of Thrips and Megalurothrips in the lowland dipterocarp forest.

Assessment of yeast diversity in a marine environment in the south of Portugal by microsatellite-primed PCR.

The occurrence and diversity of yeasts in seawater was investigated in a study site located 20 Km off Faro, Portugal, above the Alvares Cabral Trench. A total of 43 water samples from different layers (above the permanent thermocline, under the thermocline and near the bottom) and directly from the surface, originated 234 isolates. All the isolates were identified using a molecular approach that included, in a first stage, MSP-PCR fingerprinting. A total of 31 MSP-PCR classes were formed, 8 for the pigmented yeasts and 23 for the non-pigmented yeasts. The pink coloured isolates were identified by direct comparison of the new fingerprints with those obtained for representative strains of the various species. For identification of the non-pigmented yeasts, a representative isolate of each MSP-PCR class was selected for sequence analysis and compared with reference sequences. The five most abundant yeast species were Sakaguchia dacryoidea, Pseudozyma aphidis, Rhodosporidium babjevae, R. diobovatum and Debaryomyces hansenii. The distribution of isolates and species in the major taxonomic groups indicated that the number of basidiomycetous yeasts and their diversity are prevalent in relation to their ascomycetous counterpart. Diversity indices were determined and superficial water and water near the bottom had the highest diversity. The sampling effort effectiveness was estimated, and found to correspond to approximately 60% of the species present. MSP-PCR identification proved suitable for pigmented basidiomycetous yeasts and, when used in conjunction with sequence analysis, was effective for the characterization of non-pigmented populations. Our results indicate that the MSP-PCR fingerprinting method is appropriate for the characterization of large groups of isolates due to its simplicity and good reproducibility.

A region of chromosome 20 is linked to leprosy susceptibility in a South Indian population.

A major susceptibility locus for leprosy has recently been mapped on chromosome 10 (10p13) by genome-wide linkage analysis. Microsatellite markers from this genome screen that showed suggestive evidence of linkage to leprosy were evaluated in an additional 140 families with affected sib pairs. A second region of linkage has thus been identified on chromosome 20 (20p12). The peak of linkage lies at marker D20S115, which has a significant single-point maximum logarithm of odds score of 3.48 (P=.00003). Transmission disequilibrium testing of the microsatellite markers in 20p12 showed that the marker D20S835 is associated with protection against leprosy (P=.021), which suggests that a locus controlling susceptibility lies close to this marker.

A region of chromosome 20 is linked to leprosy susceptibility in a South Indian population

A major susceptibility locus for leprosy has recently been mapped on chromosome 10 (10p13) by genome-wide linkage analysis. Microsatellite markers from this genome screen that showed suggestive evidence of linkage to leprosy were evaluated in an additional 140 families with affected sib pairs. A second region of linkage has thus been identified on chromosome 20 (20p12). The peak of linkage lies at marker D20S115, which has a significant single-point maximum logarithm of odds score of 3.48 (P=.00003). Transmission disequilibrium testing of the microsatellite markers in 20p12 showed that the marker D20S835 is associated with protection against leprosy (P=.021), which suggests that a locus controlling susceptibility lies close to this marker.