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Deletion of the long arm of chromosome 20 is a common abnormality associated with myeloid malignancies. We characterized abnormalities of chromosome 20 as defined by metaphase cytogenetics (MC) in patients with myeloid neoplasms to define commonly deleted regions (CDR) and commonly retained regions (CRR) using genome-wide, high resolution single nucleotide polymorphism array (SNP-A) analysis. We reviewed the MC results of a cohort of 1,162 patients with myeloid malignancies, including myelodysplastic syndromes (MDS), MDS/myeloproliferative neoplasia (MDS/MPN), and acute myeloid leukemia (AML). We further analyzed a subcohort of 532 patients by SNP-A using the Affymetrix Genome-Wide Human SNP Array 6.0 and GeneChip Human Mapping 250K Nsp arrays. By MC, 5% (54/1,162) harbored a deletion of 20q; in 30% (16/54), del(20q) was the sole cytogenetic abnormality. By SNP-A analysis, we identified del(20q) in 23 patients, 3 not detected by MC. In four cases, monosomy 20 with a marker chromosome by MC was proven to be an interstitial deletion of 20q by SNP-A. We defined 2 CDR and 2 CRR on chromosome arm 20q: CDR1 spanned 2.5 Mb between bands 20q11.23 and 20q12, while CDR2 encompassed 1.8 Mb within 20q13.12. CRR1 spanned 1.9 Mb within 20q11.21 and CRR2 encompassed 2.5 Mb within 20q13.33. In contrast to other chromosomes frequently affected by deletions, no somatic copy neutral loss of heterozygosity (CN-LOH) was detected. Our data suggest that SNP-A is useful for the detection of cryptic aberrations of chromosome 20q and allows for a more precise characterization of complex karyotypes. Furthermore, SNP-A allowed definition of a CDR on 20q.

We investigated whether killer cell immunoglobulin-like receptor (KIR) genes are risk factor(s) for rheumatoid arthritis (RA) and its clinical manifestations. One hundred and seventy-seven RA patients and 243 healthy individuals were tested for the presence of 11 KIR genes using PCR-SSP method. The frequencies of KIRs in patients with RA were similar to the frequencies in controls. However, RA patients positive for KIR2DL3 and negative for KIR2DS3 had earlier disease diagnosis. Additionally, KIR2DL2 and KIR2DS2 were significantly more frequent among RA patients with extra-articular manifestations and in its subgroup with vasculitis than in controls and in patients without these complications. Furthermore, the frequencies of KIR2DS1 and KIR3DS1 were lower in patients without bone erosions compared with healthy individuals. Relationships between the presence or absence of autoantibodies (rheumatoid factor and anti-cyclic citrullinated peptide) and KIR frequencies were also evaluated, but no significant differences were observed. These results suggest that particular clinical manifestations of RA may have different genetic backgrounds with respect to KIR genotype.