Biomedical subjects

Ghazala Hashmi

Publications and source records attributed to Ghazala Hashmi.

3 recordsLinked to original sources

PubMed2005

A flexible array format for large-scale, rapid blood group DNA typing.

BACKGROUND: Typing for blood group antigens is currently performed by hemagglutination. The necessary reagents are becoming costly and limited in availability, and the methods are labor-intensive. The purpose of this study was to determine the feasibility of the use of large-scale DNA analysis in a microarray as a substitute for blood group typing. STUDY DESIGN AND METHODS: DNA, extracted from blood samples that had been phenotyped for some of the red blood cell antigens, was analyzed for selected blood group alleles by bead array (BeadChip, (BioArray Solutions Ltd., Warren, NJ) Illumina) [corrected] and by manual polymerase chain reaction (PCR)-based assays. Selected alleles were identified by enzyme-mediated elongation of probes, which were on color-encoded beads assembled into arrays on silicon chips. The performance of a prototype BeadChip (BioArray Solutions Ltd., Warren, NJ) [corrected] (BLOOD-1) containing single-nucleotide polymorphisms (SNPs) for FYA/B, FY-GATA, DOA/B, COA/B, LWA/B, DIA/B, and SC1/SC2 was verified with DNA from serologically characterized donors. It was then used to analyze more than 400 samples of partially defined phenotype. Samples from Chinese, Ashkenazi, and Thai donors (total n = 227) were tested with BLOOD-1. An expanded BeadChip (BioArray Solutions Ltd., Warren, NJ) [corrected] with a total of 18 SNPs (36 alleles; SNPs in BLOOD-1 and M/N, S/s, Lu(a)/Lu(b), K/k, FY265[for the Fy(X) polymorphism], Jk(a)/Jk(b), DO323[for Hy], DO350[for Jo(a)], and HgbS) was then evaluated with a subset of previously tested samples from Chinese, Ashkenazi, and New York blood donors (127) and an additional set of samples from Israeli donors (total n = 188). RESULTS: Results obtained by BeadChip (BioArray Solutions Ltd., Warren, NJ) [corrected] analysis were concordant with those obtained with the manual PCR-restriction fragment length polymorphism, allele-specific PCR, and hemagglutination assays. The frequencies of the alleles in the samples from different ethnic panels were within the expected ranges; however, two new DO alleles were discovered. CONCLUSION: It has been shown that microarray technology can be used to type DNA and detect new alleles in donor cohorts.

Alleles↗

PubMed2003

Elevated thrombopoietin levels in patients with myelofibrosis may not be due to enhanced production of thrombopoietin by bone marrow.

Thrombopoietin (TPO) is recognized as the primary regulator of megakaryocyte and platelet production. Two alternative hypotheses for the mechanism of regulation have been proposed: (1) platelet and/or megakaryocyte mass regulate circulating TPO levels by binding to TPO through TPO receptors (c-MPL), with subsequent internalization and degradation of the protein; (2) TPO mRNA produced by bone marrow (BM) stromal cells or BM cells modulates blood TPO levels or platelet counts. In myeloproliferative disorders (MPD), including primary myelofibrosis (MF) and essential thrombocythemia (ET), elevated blood TPO levels occur despite increased platelet and megakaryocyte mass. Therefore, in these diseases, elevated blood TPO levels cannot be explained by the first mechanism. The present study, was designed to measure TPO mRNA production by BM mononuclear cells and BM stromal cells using a relative RT-PCR technique, to verify the second mechanism. We found no increase of TPO mRNA production in either BM cells or in BM stromal cells in patients with MF and ET. Furthermore, in those patients with MF who had elevated plasma TPO levels, TPO mRNA levels in bone marrow fibroblasts (BMFs) or BM cells were not elevated as compared with controls. Therefore, we concluded that in patients with MF, the elevated plasma TPO levels are not due to enhanced production of TPO mRNA either by BMF, or BM cells. The TPO receptor (c-MPL) abnormalities including reduced MPL protein levels or defective TPO induced signal transduction pathways are the likely mechanisms.

Anemia, Hypochromic↗

PubMedDate not supplied

Cystic fibrosis carrier screening: validation of a novel method using BeadChip technology.

PURPOSE: To validate a novel BeadChip assay system for cystic fibrosis (CF) mutation testing using the panel of 25 ACMG recommended mutations and D1152H. METHODS: DNA from 519 individuals originally tested for CF mutation status by allele specific oligonucleotide hybridization (ASOH) were blindly analyzed by the BeadChip assay and the results were compared. The elongation mediated multiplexed analysis of polymorphisms (eMAP) protocol, which combines multiplex amplification of genomic DNA and multiplex detection of mutations on color-coded bead arrays, was used to analyze 26 CF mutations in two separate groups. RESULTS: The system accurately distinguished the 26 CF genotypes and had 100% concordance with the ASOH technique with an assay failure rate of 1.7%. Benign variants of exon 10 codons 506, 507, and 508 did not interfere with mutation identification and reflex testing for the 5/7/9T IVS8 polymorphism was performed on a separate array. CONCLUSIONS: The BeadChip assay system provided accurate and rapid identification of the ACMG recommended CF mutations.

Cystic Fibrosis↗