Biomedical subjects

Jacques Chiaroni

Publications and source records attributed to Jacques Chiaroni.

7 recordsLinked to original sources

PubMed2006

HLA-DRB1 polymorphism is associated with Kell immunisation.

K immunisation is observed in some polytransfused patients and pregnant women but does not occur in all cases of K incompatibility. This study analysed the role of genetic background in this selective response to K antigen by investigating HLA-DRB1 alleles associated with K immunisation in a southern European population. HLA-DRB1 genotyping was performed by polymerase chain reaction sequence-specific oligonucleotide/sequence-specific primer procedures in 54 K immunised patients and 200 healthy controls. The frequency of HLA-DRB1*11 was significantly higher in K immunised patients than healthy controls: 31 of 54 (57%) vs. 56 of 200 (28%) (P(c) < 0.001). In the remaining K immunised HLA-DRB1*11-negative patients, the frequency of HLA-DRB1*13 was increased: 14 of 23 (61%) vs. 49 of 144 in healthy controls (34%) (P < 0.02). The combined frequency of the two HLA-DRB1 alleles (HLA-DRB1*11 and HLA-DRB1*13) was 83% in K immunised patients when compared with 52% in healthy controls (P(c) < 0.001). K and k differ by a single amino acid T193 (M). The DRB1*11 and DRB1*13 alleles share a HLA-DRB1 gene sequence containing S in position 13, D in 70 and A in 74, and coding for the P4 pocket within the HLA-DR binding groove. This feature of the HLA-DRB1 gene could be involved in the K peptide presentation through a polymorphism ligand specific for the T193 (M) of K. In conclusion, this study demonstrated a high frequency of HLA-DRB1*11 or HLA-DRB1*13 alleles in K immunised patients, which could be due to specific K peptide presentation by HLA-DR molecules.

Alleles↗

PubMed2005

HLA-DRB1 alleles and Jk(a) immunization.

BACKGROUND: In transfusion medicine, anti-Jk(a) has been implicated in hemolytic transfusion reactions. Development of anti-Jk(a) after transfusion does not always occur after Jk(a-) patients receive at least 1 unit of Jk(a+) blood unit. This study was designed to identify HLA-DRB1 alleles associated with predisposition to Jk(a) immunization after blood transfusion or pregnancy. STUDY DESIGN AND METHODS: Genotyping by polymerase chain reaction and sequence-specific oligonucleotide probe nonradioactive hybridization/sequence-specific primers was performed in 20 Jk(a)-immunized patients and 200 controls from the same southern European population. RESULTS: Genotyping showed that HLA-DRB1*01 was significantly more frequent in Jk(a)-immunized patients than controls: 55 percent versus 17 percent (odds ratio [OR], 5.9; confidence interval [CI], 2.3-15.5; corrected p value<0.05). Because HLA-DRB1*0101, DRB1*0102, and DRB1*1001 share a common sequence in their B1 chain, that is, F in 13, R in 71, and A in 74, HLA genetic predisposition was analyzed by comparing patients and controls with respect to the distribution of F13/R71/A74-positive and -negative alleles. Results demonstrated greater positivity of the F13/R71/A74 sequence (DRB1*0101, *0102, or *1001) in patients than in controls: 65 percent versus 19.5 percent (OR, 7.7; CI, 2.9-20.5; p<0.001). CONCLUSION: In conclusion, HLA-DRB1*0101, DRB1*0102, and DRB1*1001, which share a common DRB1 sequence, appeared to be overrepresented in Jk(a)-immunized patients.

Alleles↗

PubMed2004

Distribution of rhesus blood group system in the French basques: a reappraisal using the allele-specific primers PCR method.

OBJECTIVES: To determine for the first time using PCR the distribution of Rhesus (Rh) blood group in French Basques and compare these results with those obtained by serology in the same sample and in the historical series from various Basque subgroups. METHODS: Rh polymorphism was determined in a sample of 127 autochthonous French Basques using allele-specific primers (ASP) PCR and traditional serological technique. Statistical comparisons were performed between both techniques and with the data published from various Basque subpopulations. RESULTS: No intra-sample discrepancies were detected between ASP-PCR and serology. A high frequency of RH Ddel exceeding 0.50, as typically described from several decades, was found here (0.511), as the peculiar frequency of cde (0.456) and cDE (0.073) haplotypes. This profile, obtained by molecular analysis, was within the range of previous historical studies in various Basque subpopulations using serological approach. The Rh polymorphism among the reviewed autochthonous Basque samples indicates a heterogeneous pattern of distribution, with individuals from the Alava province demonstrating the most atypical profile. CONCLUSIONS: Molecular biology approach using PCR confirms the peculiar pattern of Rh polymorphism which was previously defined by serology among Basques. Nevertheless, this distribution profile is not homogeneous within the Basque area.

Female↗

PubMed2004

Genetic characterization of the population of Grande Comore Island (Njazidja) according to major blood groups.

The Comorian population is historically considered a blend of influences from African Bantus, Arabs, and possibly Austronesians. In this study we present the first genetic data on the current Comorian population. Serologic analysis of the six major blood group systems (ABO, RH, KEL, FY, JK, and MNS) was performed on 164 individuals from Grande Comore Island (Njazidja). In addition, Duffy genotypes were determined by polymerase chain reaction using allele-specific primers. Our findings establish a high frequency of the Fy(a- b-) phenotype (86%), presenting the same genetic background as in sub-Saharan Africa. Analysis of genetic frequencies, distances, and admixture with other populations indicates that African Bantus made the main contribution to the gene pool (73.2%+/-15.5%). The Arab contribution from the Arabian peninsula was smaller (24.2%+/-7%) and the Indonesian contribution was minor (2.6%+/-9%). The major Bantu contribution was commensurate with the Bantu cultural influence. The contribution from the Arabian peninsula seemed in relation to its permeating religious and linguistic influence. As with the language, the Indonesian contribution to the Comorian gene pool was small. These results are in agreement with historical, sociological, and linguistic data.

Alleles↗

PubMed2003

Adsorption of autoantibodies in the presence of LISS to detect alloantibodies underlying warm autoantibodies.

BACKGROUND: The safe transfusion of patients with warm autoimmune hemolytic anemia requires an efficient and time-saving assay to detect alloantibodies underlying autoantibodies. Methods used include RBCs treated with ZZAP reagent, proteolytic enzyme, or untreated RBCs in the presence of PEG. We propose a method using LISS, which presents some advantages over previous methods. STUDY DESIGN AND METHODS: We evaluated the effectiveness of autoantibody adsorption with papain-treated and untreated RBCs in the presence of LISS for removal of autoantibodies, without affecting alloantibodies. RESULTS: One-hundred twenty sera containing autoantibodies were adsorbed with our routine method, which uses papain-treated allogeneic RBCs. Seven-hundred twenty adsorptions (mean, 6 per sample) and 21,600 minutes (mean, 180 min per sample) were required to remove autoantibodies. Fifty sera were adsorbed with our routine method that uses papain-treated allogeneic RBCs in the presence of LISS. The number of adsorptions and the completion time were, respectively, 144 (mean, 2.9 per sample) and 2,880 minutes (mean, 57.6 min per sample). Twenty sera were evaluated with untreated autologous RBCs, in the presence of LISS; 58 adsorptions (mean, 2.9) and 1,160 minutes (mean, 58 min per sample) were required. Three adsorptions with antigen-negative allogeneic RBCs were performed on 8 sera containing alloantibodies with weak reactivity (anti-K [1], anti-D [1], anti-Fya[2], anti-S [2], anti-E [1], and anti-Jka[1]). Alloantibodies were detected with the LISS procedure with papain-treated and untreated RBCs and the routine papain method. Alloantibodies with weak reactivity, tested against the same antibody-detection RBCs, remained unchanged following adsorption of 5 sera. An anti-S, with very weak reactivity, was no longer detected, and an anti-Jka became weaker (1+), regardless of the procedure used. One anti-D became weaker only with the LISS adsorption method. CONCLUSION: Autoantibodies can be adsorbed more efficiently in the presence of LISS.

Autoantibodies↗

PubMed2002

Partial deletion in the JK locus causing a Jk(null) phenotype.

A new alteration of the blood group JK*A allele was identified in a Jk(null) patient from Tunisia with an allo-anti-Jk3 in her serum. Southern blot and exon mapping analyses revealed an internal deletion within the Kidd (JK) locus encompassing exons 4 and 5. Sequence analysis of the Jk transcript showed that exons 4 and 5 were missing but were replaced by a 136-base-pair (bp) intron 3 sequence located 315 bp and 179 bp upstream from exon 4. This sequence is flanked by typical donor-acceptor cryptic splice sites used in the mutant but not in the normal JK gene. Because the translation initiation codon is located in exon 4, the Jk protein is not produced.

Base Sequence↗

PubMedDate not supplied

Duffy blood group genotyping in French Basques using polymerase chain reaction with allele-specific primers (PCR-ASP).

Blood group antigens such as Duffy represent interesting models for population genetics studies. The distribution of the Duffy blood group was determined using PCR in a sample of Basque (n = 126) and non-Basque (n = 110) patients from the general hospital of the French Basque Country. The frequency of FY*A allele was significantly lower among autochthonous French Basques (P < 0.001). This result, obtained for the first time by PCR analysis in this population, was within the range of previous historical studies in various Basque subpopulations using traditional hemagglutination methods. When compared with European data, our Basque sample demonstrated the lowest FY*A/FY*B ratio, this fact confirming hemotypology data published before the molecular biology era. Our results with FY*X were quite similar to those reported in European populations.

Alleles↗