The distribution of KIR-HLA functional blocks is different from north to south of Italy.

The killer cell immunoglobulin-like receptor (KIR)-human leukocyte antigen (HLA) interaction represents an example of genetic epistasis, where the concomitant presence of specific genes or alleles encoding receptor-ligand units is necessary for the activity of natural killer (NK) cells. Although KIR and HLA genes segregate independently, they co-evolved under environmental pressures to maintain particular KIR-HLA functional blocks for species survival. We investigated, in 270 Italian healthy individuals, the distribution of KIR and HLA polymorphisms in three climatic areas (from cold north to warm south), to verify their possible geographical stratification. We analyzed the presence of 13 KIR genes and genotyped KIR ligands belonging to HLA class I: HLA-C, HLA-B and HLA-A. We did not observe any genetic stratification for KIR genes and HLA-C ligands in Italy. By contrast, in a north-to-south direction, we found a decreasing trend for the HLA-A3 and HLA-A11 ligands (P = 0.012) and an increasing trend for the HLA-B ligands carrying the Bw4 epitope (P = 0.0003) and the Bw4 Ile80 epitope (P = 0.0005). The HLA-A and HLA-B KIR ligands were in negative linkage disequilibrium (correlation coefficient -0.1211), possibly as a consequence of their similar function in inhibiting NK cells. The distribution of the KIR-HLA functional blocks was different along Italy, as we observed a north-to-south ascending trend for KIR3DL1, when coupled with HLA-B Bw4 ligands (P = 0.0067) and with HLA-B Bw4 Ile80 (P = 0.0027), and a descending trend for KIR3DL2 when coupled with HLA-A3 and HLA-A11 ligands (P = 0.0044). Overall, people from South Italy preferentially use the KIR3DL1-HLA-B Bw4 functional unit, while those from the North Italy equally use both the KIR3DL2-HLA-A3/A11 and the KIR3DL1-HLA-B Bw4 functional units to fight infections. Thus, only KIR3DL receptors, which exert the unique role of microbial sensors through the specific D0 domain, and their cognate HLA-A and HLA-B ligands are selectively pressured in Italy according to geographical north-to-south distribution.

A novel HLA-B*18:80 allele identified by SBT typing in an Italian bone marrow volunteer donor.

A novel allele, officially named B*18:80, was detected in a Caucasoid individual by polymerase chain reaction-sequence-specific primers and SBT. The new allele differs from B*18:01:01 at two nucleotidic positions in codon 24 at exon 2.

Detection of a novel HLA-B allele, HLA-B*08:111, in an Italian bone marrow donor.

The newly detected HLA-B*08:111 allele shows two nucleotide differences from B*08:01:01 in codons 113 and 114.

Identification of a new allele, HLA-DRB1*1366*.

High-resolution polymerase chain reaction sequence-specific primer typing of the human leucocyte antigen (HLA)-DRB1 gene of an Italian patient candidate for bone marrow transplantation revealed a new allelic variant of HLA-DRB1*13. The sequence was named DRB1*1366, and comparison with previously described DRB1 alleles demonstrated the two closely related sequences were HLA-DRB1*1330 and HLA-DRB1*130302.

A repository of 14 PCR-loci Italian gene frequencies in the World Wide Web.

A collection of 6830 typing results produced by the Immunohematology Laboratory at the UCSC, pertaining to 11 STRs (FES/FPS, vWA31, HUMTH01, F13A1, MBP, D21S11, D7S460, D18S51, CD4, TPOX, CSF1PO) and 3 AmpFLPs (D1S80, APO-B, COL2A1), is publicly available as an electronic archive at a website.

Fluorescence-based classification of microsatellites using a single-wavelength semiautomatic sequencer: genotype assignment and identity tests by analysis of comigrating peak profiles.

Microsatellite analysis, based on fluorescein labeling and reading through a semiautomatic single wavelength sequencer, is described. Pairs of labeled polymerase chain reaction (PCR) samples, mixed in equimolar proportion, were electrophoresed and the specific peaks read in a single gel lane. Identity was asserted when peaks overlapped in a unique fluorescent signal which, compared with individual sample profiles, had a twofold intensity. Classification was achieved by blending individual PCR products to 'locus specific allelic ladders' (composite samples containing a repertory of fragments allelic to a given locus) and by noticing the specific peak enhancement. The resulting protocol of analysis assigned no size and classified allelic forms by tandem repeat number. Applied to a large repertory of PCR products and compared with manual electrophoresis, this protocol proved to be reliable and reduced times and costs of genotype analysis. Analysis of comigrating peak profiles is highly objective and provides convincing evidence for diagnostics and identity tests.

Distribution of alleles and genotypes from three hypervariable DNA loci in individuals from central and southern Italy.

Three hypervariable locus-specific DNA probes (D2S44, alpha globin 3'HVR, D12S11) used in the routine typing activities of our laboratory have been studied using a representative sample of individuals from central and southern Italy. We report allele and genotype distribution of these systems, and discuss several problems met when typing quasi-continuous arrays of restriction fragments.

Molecular and cytogenetic characterization of a Chinese hamster/human hybrid cell line containing a der (21)t(Ypter-->cenY::cen21-->21qter) chromosome.

Human/rodent somatic cell hybrids have been exceedingly useful in assigning human genes and DNA sequences to specific human chromosomes. As new technologies for analyzing the human chromosome complement of such human/rodent hybrid cells become available, it is of critical importance that these be applied to enhance characterization of existing hybrids. This is particularly important since human chromosomes in such hybrids have been observed to rearrange with time. We report here the use of fluorescence in situ hybridization of DNA probes to metaphase chromosomes to analyze one hybrid designated 72532X6. This analysis shows that the chromosome suspected to be a normal human chromosome 21 in this hybrid is actually a translocation chromosome containing Yp and 21q. In addition, the hybrid contains a fragment of human chromosome 9 translocated to a Chinese hamster chromosome. Analysis of the chromosomes from the human donor indicates that his chromosomes are normal. Thus, this translocation chromosome appears to have arisen after formation of the hybrid.

Errors in sizing bands of hypervariable DNA profiles on autoradiograms: are they Gaussian?

The accuracy of procedures for sizing hypervariable restriction fragments by Southern blot analysis (SBA) has been tested under three different experimental conditions: (i) intrablot serial analyses: three heterozygous DNA profiles were tested 14 times each in the same gel electrophoresis; (ii) intralaboratory analyses: we replicated three profiles (six autoradiographic bands) in over 100 SBA experiments; (iii) interlaboratory analyses: 15 serial measurements produced in a recent collaborative study (Forensic Sci. Int. 1991, 49, 1-15) were taken into account. In these three cases, a typical U-shaped correlation curve between molecular size and coefficient of variation was found. We explain decrease of accuracy at both extremities of the gels in terms of: (i) enlarged shapes of bands and mean electrophoretic resolution at the cathode; (ii) diffusion and blurring of bands at the anodal edge. The three populations of data were subjected to a chi 2 test and to the Kolmogorov-Smirnov test in order to verify their compliance with normal distribution. Twenty-three out of 27 tests indicated no significant deviation from the assumption of Gaussian distribution. We recommend the adoption of tests for normality to validate the use of symmetric confidence intervals for calculating gene frequencies and asserting a match between adjacent bands.

Molecular study of parental origin of extra chromosome 21 in regular and de novo translocation trisomies.

The parental origin of the extra chromosome 21 (or extra 21q) was determined in seven informative families with a Down syndrome (DS) child by using molecular polymorphisms. Five DS patients had regular trisomy, one a de novo 14/21 translocation and another a de novo 21/21 translocation or isochromosome 21q. In four families with regular trisomy, the extra chromosome was of maternal origin, and in one family it was paternally derived. In the two families with a de novo aberration, both the 14/21 translocation and 21/21 rearrangement originated during maternal meiosis. For a better evaluation of the stage of meiotic error and the occurrence of crossovers between nondisjoined chromosomes, the regional map position of four of the nine informative DNA markers, used in this study, was refined, leading to useful localizations in both centromeric and distal regions. Recombination events were found in two families with regular trisomy, one occurring between chromosomes 21 that failed to disjoin at maternal meiosis I, the other prior to a paternal meiosis II nondisjunction.