Molecular Pathology in Transfusion Medicine: New Concepts and Applications.

Virtually all the red blood cell and platelet antigen systems have been characterized at the molecular level. Highly reliable methods for red blood cell and platelet antigen genotyping are now available. Genotyping is a useful adjunct to traditional serology and can help resolve complex serologic problems. Although red blood cell and platelet phenotypes can be inferred from genotype, knowledge of the molecular basis is essential for accurate assignment. Genotyping of blood donors is an effective method of identifying antigen-negative and/or particularly rare donors. Cell-free DNA analysis provides a promising noninvasive method of assessing fetal genotypes of blood group alloantigens.

Molecular pathology in transfusion medicine.

This article provides an overview of the application of molecular diagnostic methods to red cell and platelet compatibility testing. The advantages and limitations of molecular methods are evaluated compared with traditional serologic methods. The molecular bases of clinically significant red cell and platelet antigens are presented. Current recommendations for reporting molecular assay results and distinctions between genotype and phenotype are discussed.

Isolation and characterization of a novel gene, xMADML, involved in Xenopus laevis eye development.

We have identified Xenopus MADM-like (xMADML), a Xenopus laevis gene related to the murine MADM and the human NRBP genes. xMADML is expressed throughout early development and is expressed most strongly in the developing lens and more weakly in the retina and other anterior tissues. We demonstrate that disruption of xMADML translation by means of morpholino injection results in impaired retina and lens development. Reciprocal transplantation of the presumptive lens ectoderm between morpholino-injected embryos and those injected solely with a dextran lineage tracer demonstrates that xMADML is necessary in both the lens and the retina for correct development of these eye tissues. Analysis of gene expression after knockdown of xMADML revealed significant alterations in the expression of some genes, including Pax6, xSix3, Sox2, and Sox3, suggesting that xMADML plays a role in regulating gene expression during development of the eye. This investigation is the first in vivo study examining the developmental role of this novel gene and reveals an important role of xMADML in eye tissue development and differentiation.

Molecular profiling: gene expression reveals discrete phases of lens induction and development in Xenopus laevis.

PURPOSE: Experimental tissue transplant studies reveal that lens development is directed by a series of early and late inductive interactions. These interactions impart a growing lens-forming bias within competent presumptive lens ectoderm that leads to specification and the commitment to lens fate. Relatively few genes are known which control these events. Identification of additional genes expressed during lens development may reveal key players in these processes and help to characterize these tissue properties. METHODS: A large suite of genes has been isolated that are expressed during the process of cornea-lens transdifferentiation (lens regeneration) in Xenopus laevis. Many of these genes are also expressed during embryonic lens development. Genes were selected for expression analysis via in situ hybridization. This group consisted of clones with possible roles in cell determination and differentiation as well as novel clones without previous identities. The spatiotemporal expression of these genes in conjunction with previously described genes were correlated with key events during embryonic lens formation. RESULTS: Eighteen of the thirty clones analyzed via in situ hybridization demonstrated observable expression in the developing lens. These genes were initially expressed in the presumptive lens ectoderm at a variety of timepoints throughout development. Expression is restricted to discrete time intervals during lens development. However, in most cases, expression was maintained throughout lens development after being initially upregulated. CONCLUSIONS: The expression of these genes suggests that a genetic hierarchy exists in which an increasing number of genes are upregulated and their expression is maintained throughout lens development. Suites of genes appear to be upregulated at specific timepoints during development, correlating with stages of lens induction, specification, commitment, lens placode formation, and lens differentiation, while suites at additional timepoints suggest that other, previously unreported stages exist as well. This analysis provides a genetic framework for characterizing these processes of lens development.