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Distribution of seven killer cell immunoglobulin-like receptors in a southeast brazilian population
Abstracts
S119
99-P
DISTRIBUTION OF SEVEN KILLER CELL IMMUNOGLOBULIN-LIKE RECEPTORS IN A SOUTHEAST BRAZILIAN POPULATION Rafael G. Vargas, Maria da Grac¸a Bicalho. Genetics Department, Laboratory of Immunogenetics and Histocompatibility – LIGH, Federal University of Parana – UFPR, Curitiba, Parana, Brazil Aim: The aim of the present study is to characterize the frequencies of seven KIR genes in a Southeast Brazilian Caucasoid population, and to analyze similarities and differences with KIR gene frequencies in other Caucasoid populations. Methods: In the present study we have determined the frequencies of seven KIR genes in a panel of 90 unrelated healthy Brazilian Caucasians. We have typed genomic DNA for the presence of the putative KIR loci KIR2DL1, KIR2DL2, KIR2DL3, KIR2DL4, KIR2DS1, KIR2DS2 and KIR2DS4 using polymerase chain reaction sequence-specific primers (PCR-SSP). The frequencies of KIR loci and profiles of Brazilian Caucasians were compared with other Caucasoid populations studies performed in Caucasoid populations from Greece, USA, Australia, Ireland and UK. The non-random association between the presence of particular KIR genes in different populations was tested by Fisher’s exact test using 2⫻2 contingency tables, the level of significance was set at 0.05 and p-values were subjected to correction for the number of loci investigated. Scope: The interaction between killer cell immunoglobulin-like receptors (KIR) expressed on natural killer (NK) cells, and human leukocyte antigen (HLA) class I molecules expressed on target cells is known to regulate the cytolytic activity of NK cells. A wide range of KIR repertoires is observed in the population because the number of KIR loci can vary between individuals, resulting in a heterogeneous KIR profile. Discrepancies in KIR genes frequencies between different Caucasoid populations could be an indicative of the critical role of the geographical distribution of an ethnical group in the frequencies of several KIR loci and profiles Overall, the gene frequency of most KIRs in this study was similar to that reported for others populations, except for the inhibitory KIR2DL1 locus that presented a significant lower frequency in the Brazilian Caucasoid population when compared with a Greek Caucasoid population (p⫽0,0257) and with a grouping of Caucasoid populations (from USA, Australia, Ireland and UK) (p⬍0,0001). For the noninhibitory KIR2DS1 locus we observed a higher frequency in the Brazilian population when compared with the Greek Caucasoid population (p⫽0,0158). Conclusions: The results of the KIR genes frequencies comparisons show that several similarities exist between different Caucasoid populations, but Brazilian population still distinguishes itself by the decreased frequencies of KIR2DL1 and increased of KIR2DS1 genes This variability could provide the basis for embattled and diversified NK cell responses to infection across the geographical distribution of different Caucasoid groups.
100-P
A RARE STR HOMOZYGOUS NULL PHENOTYPE Monica Jensen, David Baumgarten, Zahra MehdizadehKashi. HLA Laboratory, American Red Cross, Portland, OR, USA Aim: The short tandem repeat (STR) loci are PCR-based genetic used in human identity testing. Commercial kits for multiplex typing of STR loci are available, however, kits from different manufacturers use different primer sets. Null alleles are typically the result of a mutation in one of the PCR primer binding sites. Consequently, a sample may demonstrate allele dropout when typed by a primer set from one manufacturer’s kit and not when typed by another manufacturer’s kit. Null alleles can lead to significant challenges in paternity establishment, as parent and child can appear to be homozygous for different alleles. In other words, the allele dropout may cause a heterozygous specimen appear falsely as a homozygote. We report the presence of a null allele at the D13S317 locus in an African American Alleged Father, his daughter, and the two children resulting from the rape/incest of the daughter. One of the children had an extremely rare homozygous null phenotype, resulting in no visible bands. The other three individuals appeared phenotypically homozygous. The presence of a mutant site was confirmed when the samples, originally amplified using Promega Corporation primers, revealed an additional band when reamplified with different primers manufactured by Applied Biosystems. Methods: Highly polymorphic regions that have short repeated sequences of DNA known as STR loci were targeted with sequence-specific primers and were amplified using PCR. The resulted DNA fragments were then separated and detected using gel electrophoresis. We used a polyacrylamide gel to separate the DNA fragments. Following electropheresis, we silver stained the gel prior to scanning the entire gel into a computer. The produced image showed all of the bands corresponding to different repeat sizes and the allelic ladder included on the gel. Results were analyzed and interpreted. Scope: The frequency of null alleles is difficult to determine, as their presence is suspected only in cases where parent-child data is available. The most recent AABB data shows that 3 null alleles were suspected in the black population in D13S317. However, the total number of independent samples run in all reporting laboratories is unclear. Conclusions: In general, the current primer sets from commercial manufacturers do not produce considerable number of null allele. This may in part be due to the fact that the laboratories routinely submit the variant alleles to the AABB for the Annual Survey. In order to reduce such challenges, the respective manufacturers should be notified to modify the primers such that the amplification of the recognized mutants is achieved.
S119
99-P
DISTRIBUTION OF SEVEN KILLER CELL IMMUNOGLOBULIN-LIKE RECEPTORS IN A SOUTHEAST BRAZILIAN POPULATION Rafael G. Vargas, Maria da Grac¸a Bicalho. Genetics Department, Laboratory of Immunogenetics and Histocompatibility – LIGH, Federal University of Parana – UFPR, Curitiba, Parana, Brazil Aim: The aim of the present study is to characterize the frequencies of seven KIR genes in a Southeast Brazilian Caucasoid population, and to analyze similarities and differences with KIR gene frequencies in other Caucasoid populations. Methods: In the present study we have determined the frequencies of seven KIR genes in a panel of 90 unrelated healthy Brazilian Caucasians. We have typed genomic DNA for the presence of the putative KIR loci KIR2DL1, KIR2DL2, KIR2DL3, KIR2DL4, KIR2DS1, KIR2DS2 and KIR2DS4 using polymerase chain reaction sequence-specific primers (PCR-SSP). The frequencies of KIR loci and profiles of Brazilian Caucasians were compared with other Caucasoid populations studies performed in Caucasoid populations from Greece, USA, Australia, Ireland and UK. The non-random association between the presence of particular KIR genes in different populations was tested by Fisher’s exact test using 2⫻2 contingency tables, the level of significance was set at 0.05 and p-values were subjected to correction for the number of loci investigated. Scope: The interaction between killer cell immunoglobulin-like receptors (KIR) expressed on natural killer (NK) cells, and human leukocyte antigen (HLA) class I molecules expressed on target cells is known to regulate the cytolytic activity of NK cells. A wide range of KIR repertoires is observed in the population because the number of KIR loci can vary between individuals, resulting in a heterogeneous KIR profile. Discrepancies in KIR genes frequencies between different Caucasoid populations could be an indicative of the critical role of the geographical distribution of an ethnical group in the frequencies of several KIR loci and profiles Overall, the gene frequency of most KIRs in this study was similar to that reported for others populations, except for the inhibitory KIR2DL1 locus that presented a significant lower frequency in the Brazilian Caucasoid population when compared with a Greek Caucasoid population (p⫽0,0257) and with a grouping of Caucasoid populations (from USA, Australia, Ireland and UK) (p⬍0,0001). For the noninhibitory KIR2DS1 locus we observed a higher frequency in the Brazilian population when compared with the Greek Caucasoid population (p⫽0,0158). Conclusions: The results of the KIR genes frequencies comparisons show that several similarities exist between different Caucasoid populations, but Brazilian population still distinguishes itself by the decreased frequencies of KIR2DL1 and increased of KIR2DS1 genes This variability could provide the basis for embattled and diversified NK cell responses to infection across the geographical distribution of different Caucasoid groups.
100-P
A RARE STR HOMOZYGOUS NULL PHENOTYPE Monica Jensen, David Baumgarten, Zahra MehdizadehKashi. HLA Laboratory, American Red Cross, Portland, OR, USA Aim: The short tandem repeat (STR) loci are PCR-based genetic used in human identity testing. Commercial kits for multiplex typing of STR loci are available, however, kits from different manufacturers use different primer sets. Null alleles are typically the result of a mutation in one of the PCR primer binding sites. Consequently, a sample may demonstrate allele dropout when typed by a primer set from one manufacturer’s kit and not when typed by another manufacturer’s kit. Null alleles can lead to significant challenges in paternity establishment, as parent and child can appear to be homozygous for different alleles. In other words, the allele dropout may cause a heterozygous specimen appear falsely as a homozygote. We report the presence of a null allele at the D13S317 locus in an African American Alleged Father, his daughter, and the two children resulting from the rape/incest of the daughter. One of the children had an extremely rare homozygous null phenotype, resulting in no visible bands. The other three individuals appeared phenotypically homozygous. The presence of a mutant site was confirmed when the samples, originally amplified using Promega Corporation primers, revealed an additional band when reamplified with different primers manufactured by Applied Biosystems. Methods: Highly polymorphic regions that have short repeated sequences of DNA known as STR loci were targeted with sequence-specific primers and were amplified using PCR. The resulted DNA fragments were then separated and detected using gel electrophoresis. We used a polyacrylamide gel to separate the DNA fragments. Following electropheresis, we silver stained the gel prior to scanning the entire gel into a computer. The produced image showed all of the bands corresponding to different repeat sizes and the allelic ladder included on the gel. Results were analyzed and interpreted. Scope: The frequency of null alleles is difficult to determine, as their presence is suspected only in cases where parent-child data is available. The most recent AABB data shows that 3 null alleles were suspected in the black population in D13S317. However, the total number of independent samples run in all reporting laboratories is unclear. Conclusions: In general, the current primer sets from commercial manufacturers do not produce considerable number of null allele. This may in part be due to the fact that the laboratories routinely submit the variant alleles to the AABB for the Annual Survey. In order to reduce such challenges, the respective manufacturers should be notified to modify the primers such that the amplification of the recognized mutants is achieved.