Characterisation of the novel HLA-G null allele, HLA-G*01:21N, in Finnish individuals.

We identified the novel HLA-G*01:21N null allele in Finnish Caucasian individuals.

Identification of a new HLA-G allele, HLA-G*01:18, in a Canadian Caucasian individual.

We identified a novel HLA-G allele with a protein-modifying mutation in a Canadian Caucasian Individual.

Identification of two new HLA-G alleles, G*01:01:03:03 and G*01:01:21, in Brazilian individuals.

Here we report two new non-classical class I HLA-G alleles found in the Brazilian population.

Non-classical HLA-E gene variability in Brazilians: a nearly invariable locus surrounded by the most variable genes in the human genome.

The non-classical human leukocyte antigen (HLA) class I genes present a very low rate of variation. So far, only 10 HLA-E alleles encoding three proteins have been described, but only two are frequently found in worldwide populations. Because of its historical background, Brazilians are very suitable for population genetic studies. Therefore, 104 bone marrow donors from Brazil were evaluated for HLA-E exons 1-4. Seven variation sites were found, including two known single nucleotide polymorphisms (SNPs) at positions +424 and +756 and five new SNPs at positions +170 (intron 1), +1294 (intron 3), +1625, +1645 and +1857 (exon 4). Haplotyping analysis did show eight haplotypes, three of them known as E*01:01:01, E*01:03:01 and E*01:03:02:01 and five HLA-E new alleles that carry the new variation sites. The HLA-E*01:01:01 allele was the predominant haplotype (62.50%), followed by E*01:03:02:01 (24.52%). Selective neutrality tests have disclosed an interesting pattern of selective pressures in which balancing selection is probably shaping allele frequency distributions at an SNP at exon 3 (codon 107), sequence diversity at exon 4 and the non-coding regions is facing significant purifying pressure. Even in an admixed population such as the Brazilian one, the HLA-E locus is very conserved, presenting few polymorphic SNPs in the coding region.

Identification of six new HLA-G alleles with non-coding DNA base changes.

We identified six novel human leukocyte antigen-G alleles with synonymous mutations in Caucasian and/or African populations.

Characterisation of five novel HLA-G alleles with coding DNA base changes.

We identified five novel human leukocyte antigen-G alleles with protein-modifying mutations in Caucasian and/or African populations.

Evaluation of a vanA-specific PCR assay for detection of vancomycin-resistant Enterococcus faecium during a hospital outbreak.

We investigated the use of PCR as an alternative to culture of fecal samples for detection of vanA-containing Enterococcus faecium during a recent hospital outbreak. Rectal swabs collected consecutively from 223 patients were analyzed by culture with and without enrichment broth and by vanA-specific PCR of enrichment broth samples. Fifty-five specimens were positive for vanA-containing E. faecium by at least one method. The sensitivities of the vanA-specific PCR assay and agar culture with and without enrichment broth were 94.5, 98, and 89%, respectively. All three methods were 100% specific. Final results were obtained much more rapidly by PCR (within 24 to 30 h of specimen submission) than by the culture methods (4 to 5 days). Thus, PCR is an accurate and rapid alternative to culture for detection of vancomycin-resistant enterococci during hospital outbreaks.

Mutation analysis of the BRCA2 gene in 49 site-specific breast cancer families.

The hereditary breast cancer gene BRCA2 was recently cloned and is believed to account for almost half of site-specific breast cancer families and the majority of male breast cancer families. We screened 49 site-specific breast cancer families for mutations in the BRCA2 gene using single strand conformation analysis (SSCA) followed by direct sequencing. We found mutations in eight families, including all four families with male breast cancer. The eight mutations were small deletions with the exception of a single nonsense mutation, an all were predicted to interrupt the BRCA2 coding sequence and to lead to a truncated protein product. Other factors which predicted the presence of a BRCA2 mutation included a case of breast cancer diagnosed at age 35 or below (P = 0.01) and a family history of pancreatic cancer (P = 0.03). Two mutations were seen twice, including a 8535delAG, which was detected in two French Canadian families. Our results suggest the possibility that the proportion of site-specific breast cancer families attributable to BRCA2 may be overestimated.

Presymptomatic diagnosis for neurofibromatosis 2 with chromosome 22 markers.

Neurofibromatosis 2 (NF2) is a dominantly inherited disorder characterized by multiple tumors of the central nervous system, predominantly bilateral vestibular schwannomas. The gene for NF2 is located in the chromosomal region 22q12 between the loci D22S1 and D22S28. We have performed genetic linkage analysis on 13 NF2 families with a total of nine polymorphic DNA markers, including five which we have recently mapped to this region. Two loci, D22S32 and NEFH, are linked to the NF2 locus at 0% recombination (lod scores of 6.03 and 4.28, respectively). By multipoint linkage analysis, we assign the NF2 gene to an interval of 7 cM, between the loci D22S212 and D22S28. We have used this set of nine markers to construct chromosome 22 haplotypes for the 82 at-risk individuals in this pedigree set. It has been possible to determine, with a high degree of certainty, the carrier status of 70 (85%) of these at-risk individuals. Risk prediction was possible in every case where DNA was available from both parents. Fifty-three of the 70 (76%) informative individuals were assigned decreased risks of being carriers. The use of chromosome 22 probes for risk assessment should result in a greatly reduced number of individuals who require periodic screening for NF2.