Genotypic evaluation of killer immunoglobulin-like receptors in NK-type lymphoproliferative disease of granular lymphocytes

Using polymerase chain reaction (PCR)-based sequence-specific primers, the killer immunoglobulin-like receptor (KIR) genotypes of 35 patients with natural killer (NK)-type lymphoproliferative disease of granular lymphocytes and of 50 normal subjects were investigated to evaluate whether genes coding for activating KIRs were more frequently detected in patients with NK-lymphoproliferative disease of granular lymphocytes (LDGL). Genotype frequency indicated that the most frequently found gene content was eight genes in controls and 14 in patients (P<0.05). The KIR genotype analysis revealed that patient and, surprisingly, control KIR genotypes preferentially consisted of type B haplotypes characterized by the presence of multiple-activating KIRs. Evidence was also provided that the same KIR genotype was shared by a variable number of patients. Interestingly, the recurrent genotypes observed in the patient group were not found in controls. Concerning inhibitory genes, KIR2DL5a and 2DL5b were more frequently detected in patients than in controls (P<0.01), likely representing a discrete feature of the genetic repertoire of the patients. KIR gene repertoire analysis in patients suggests that the susceptibility to NK-LDGL might be related to the presence of activating KIR genes and supports the concept that these receptors may be involved in the priming of granular lymphocytes (GL) proliferation. Population analysis might disclose a genetic background predisposing to this disease

Audiological phenotypes of connexin gene mutation patterns: A glance on different GJB2/GJB6 gene mutation profiles

GJB2 mutations are the most common cause of autosomal-recessive non-syndromic sensorineural hearing loss (SNHL). The available evidence shows large phenotypic variability across different genotypes and allelic variants. The aim of this study was to investigate the clinical and audiological features of a cohort of subjects with different GJB2/GJB6 gene mutation profiles from a tertiary referral center in Northeastern Italy. We considered 57 patients with GJB2/GJB6 mutations presenting with congenital, non-syndromic SNHL, mainly coming from the Veneto region (Italy). The samples were screened for mutations in exons 1 and 2 of the GJB2 gene and for the GJB6 gene deletion del (GJB6-D13S1830). Free-field and air-conduction frequency-specific thresholds and the pure-tone average (PTA) were considered in the statistical analysis. Five patients (8.87%) had connexin gene mutations in simple heterozygosis, 15 (26.31%) in compound heterozygosis, 34 (59.64%) in homozygosis, and 3 (5.26%) with digenic patterns. The frequency-specific airconduction thresholds showed significantly different mean values across the different genotypes (Roy’s largest-root test, p = 0.0473). Despite the evidence already available on genetic SNHL, many new insights are to be expected. Further large-scale prospective studies including different populations are necessary to confirm these preliminary findings about the clinical and audiological features of patients with different GJB2/GJB6 gene mutation patterns

Audiological Phenotypes of Connexin Gene Mutation Patterns: A Glance at Different GJB2/GJB6 Gene Mutation Profiles

GJB2 mutations are the most common cause of autosomal-recessive non-syndromic sensorineural hearing loss (SNHL). The available evidence shows large phenotypic variability across different genotypes and allelic variants. The aim of this study was to investigate the clinical and audiological features of a cohort of subjects with different GJB2/GJB6 gene mutation profiles from a tertiary referral center in Northeastern Italy. We considered 57 patients with GJB2/GJB6 mutations presenting with congenital, non-syndromic SNHL, mainly coming from the Veneto region (Italy). The samples were screened for mutations in exons 1 and 2 of the GJB2 gene and for the GJB6 gene deletion del (GJB6-D13S1830). Free-field and air-conduction frequency-specific thresholds and the pure-tone average (PTA) were considered in the statistical analysis. Five patients (8.87%) had connexin gene mutations in simple heterozygosis, 15 (26.31%) in compound heterozygosis, 34 (59.64%) in homozygosis, and 3 (5.26%) with digenic patterns. The frequency-specific air-conduction thresholds showed significantly different mean values across the different genotypes (Roy’s largest-root test, p = 0.0473). Despite the evidence already available on genetic SNHL, many new insights are to be expected. Further large-scale prospective studies including different populations are necessary to confirm these preliminary findings about the clinical and audiological features of patients with different GJB2/GJB6 gene mutation patterns

Lack of expression of inhibitory KIR3DL1 receptor in patients with natural killer cell-type lymphoproliferative disease of granular lymphocytes

BACKGROUND:Natural killer cell-type lymphoproliferative disease of granular lymphocytes is a disorder characterized by chronic proliferation of CD3(-)CD16(+) granular lymphocytes. By flow cytometry analysis, we previously demonstrated a dysregulation in killer immunoglobulin-like receptor (KIR) expression in natural killer cells from patients with this lymphoproliferative disease, the activating KIR receptors being mostly expressed. We also found that patients with natural killer cell-type lymphoproliferative disease of granular lymphocytes usually had KIR genotypes characterized by multiple activating KIR genes.DESIGN AND METHODS:We investigated the mRNA levels of the KIR3DL1 inhibitory and the related KIR3DS1 activating receptors in 15 patients with natural killer cell-type lymphoproliferative disease of granular lymphocytes and in ten controls. These genes are usually expressed when present in the genome of the Caucasian population.RESULTS: We demonstrated the complete lack of KIR3DL1 expression in most of the patients analyzed, with the receptor being expressed in 13% of patients compared to in 90% of controls (P<0.01). Interestingly, studies of the methylation patterns of KIR3DL1 promoter showed a significantly higher methylation status (0.76 \ub1 0.12 SD) in patients than in healthy subjects (0.49\ub10.10 SD, P<0.01). The levels of expression of DNA methyl transferases, which are the enzymes responsible for DNA methylation, did not differ between patients and controls.CONCLUSIONS:In this study we showed, for the first time, a consistent down-regulation of the inhibitory KIR3DL1 signal due to marked methylation of its promoter, thus suggesting that together with the increased expression of activating receptors, the lack of the inhibitory signal could also play a role in the pathogenesis of natural killer cell-type lymphoproliferative disease of granular lymphocytes