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Wayne W Grody

Publications and source records attributed to Wayne W Grody.

30 records · Page 2Linked to original sources
PubMed2002

Expression of the liver form of arginase in erythrocytes.

Arginase I (AI) has a critical function in mammalian liver as the final enzyme in the urea cycle responsible for the disposal of ammonia from protein catabolism. AI is also expressed in various extrahepatic tissues and may play a role in regulating arginine levels and in providing ornithine for biosynthetic reactions that generate various critical intermediary metabolites such as glutamate, glutamine, GABA, agmatine, polyamines, creatine, proline, and nitric oxide. AI is expressed in red blood cells (RBCs) only in humans and certain higher primates. Macaca fascicularis has been identified as an evolutionary transition species in which RBC-AI expression is co-dominantly regulated. The M. fascicularis AI gene was analyzed to understand AI expression in erythrocytes. Erythroid progenitor cells [nucleated red blood cells (nRBCs)] isolated from cord blood were utilized to demonstrate AI expression by immunocytochemical staining using anti-AI antibody. Introduction of EGFP reporter vectors into nRBC showed that the proximal 1.2 kbp upstream of the AI gene is sufficient for AI expression. Expression of a second arginase isoform, AII, in nRBCs was discovered by cDNA profiling. This contrasts with mature fetal or adult RBCs which contain only the AI protein. In addition, an alternatively spliced AI (AI(')) variant was observed from erythroid mRNA analysis with an alternative splice acceptor site located within intron 2, causing the insertion of eight additional amino acids yet retaining significant enzymatic activity.

Alternative Splicing↗
PubMed2002

Mouse model for human arginase deficiency.

Deficiency of liver arginase (AI) causes hyperargininemia (OMIM 207800), a disorder characterized by progressive mental impairment, growth retardation, and spasticity and punctuated by sometimes fatal episodes of hyperammonemia. We constructed a knockout mouse strain carrying a nonfunctional AI gene by homologous recombination. Arginase AI knockout mice completely lacked liver arginase (AI) activity, exhibited severe symptoms of hyperammonemia, and died between postnatal days 10 and 14. During hyperammonemic crisis, plasma ammonia levels of these mice increased >10-fold compared to those for normal animals. Livers of AI-deficient animals showed hepatocyte abnormalities, including cell swelling and inclusions. Plasma amino acid analysis showed the mean arginine level in knockouts to be approximately fourfold greater than that for the wild type and threefold greater than that for heterozygotes; the mean proline level was approximately one-third and the ornithine level was one-half of the proline and ornithine levels, respectively, for wild-type or heterozygote mice--understandable biochemical consequences of arginase deficiency. Glutamic acid, citrulline, and histidine levels were about 1.5-fold higher than those seen in the phenotypically normal animals. Concentrations of the branched-chain amino acids valine, isoleucine, and leucine were 0.4 to 0.5 times the concentrations seen in phenotypically normal animals. In summary, the AI-deficient mouse duplicates several pathobiological aspects of the human condition and should prove to be a useful model for further study of the disease mechanism(s) and to explore treatment options, such as pharmaceutical administration of sodium phenylbutyrate and/or ornithine and development of gene therapy protocols.

Animals↗
PubMed2001

Molecular genetic risk screening.

Under the impetus of the Human Genome Project, new disease-associated genes are being discovered at a rapid pace. Mutations in many of these genes are present in a high enough proportion of the general population, or of particular ethnic groups, that global or targeted population screening can be contemplated. If performed early enough, identification of these mutations by molecular genetic testing can be used not merely to diagnose disease but to predict risk of future disease, either in the individual being tested or in his or her offspring. In some cases this knowledge can be the rationale for heightened surveillance and/or preventive or therapeutic interventions. Mass screening has already commenced for cystic fibrosis mutations and has been discussed for such diverse diseases as hereditary hemochromatosis, thrombophilias, familial cancer predispositions, and pharmacogenetic risk factors. However, implementation of such programs is often impeded by the complexity of the gene mutations, by incomplete penetrance, and by thorny ethical and social issues. This chapter reviews the basic criteria to be considered before embarking on population genetic risk screening, and examines multiple disease-screening examples representing a variety of modes of inheritance and technical challenges.

Cystic Fibrosis↗
PubMedDate not supplied

Standards and guidelines for CFTR mutation testing.

One mission of the ACMG Laboratory Quality Assurance (QA) Committee is to develop standards and guidelines for clinical genetics laboratories, including cytogenetics, biochemical, and molecular genetics specialties. This document was developed under the auspices of the Molecular Subcommittee of the Laboratory QA Committee by the Cystic Fibrosis (CF) Working Group. It was placed on the "fast track" to address the preanalytical, analytical, and postanalytical quality assurance practices of laboratories currently providing testing for CF. Due to the anticipated impact of the ACMG recommendation statement endorsing carrier testing of reproductive couples, it was viewed that CF testing would increase in volume and that the number of laboratories offering CF testing would also likely increase. Therefore, this document was drafted with the premise of providing useful information gained by experienced laboratory directors who have provided such testing for many years. In many instances, "tips" are given. However, these guidelines are not to be interpreted as restrictive or the only approach but to provide a helpful guide. Certainly, appropriately trained and credentialed laboratory directors have flexibility to utilize various testing platforms and design testing strategies with considerable latitude. We felt that it was essential to include technique-specific guidelines of several current technologies commonly used in laboratories providing CF testing, since three of the four technologies discussed are available commercially and are widely utilized. We take the view that these technologies will change, and thus this document will change with future review.

Cystic Fibrosis↗
PubMedDate not supplied

Estimated analytic validity of HFE C282Y mutation testing in population screening: the potential value of confirmatory testing.

PURPOSE: The purpose of this study was to estimate analytic sensitivity and specificity of HFE testing for C282Y homozygosity in the hypothetical setting of population screening for hemochromatosis. METHODS: We analyzed published results of the Molecular Genetics Survey performed by the American College of Medical Genetics/College of American Pathologists between 1998 and 2002, taking into account its educational nature. RESULTS: Analytic sensitivity for C282Y homozygosity is 98.4% (95% CI 95.9%-99.5%). The analytic specificity is 99.8% (99.4%-99.9%). At a frequency of 40 per 10,000 for the homozygous genotype, the analytic positive predictive value is 66%. CONCLUSION: HFE testing for C282Y homozygosity is highly reliable. Homozygosity is uncommon in population screening, however, and confirmatory testing should be considered.

Genetic Testing↗
PubMedDate not supplied

Bayesian analysis for cystic fibrosis risks in prenatal and carrier screening.

PURPOSE: Risk assessment is an essential component of genetic counseling and testing, and Bayesian analysis plays a central role in complex risk calculations. We previously developed generalizable Bayesian methods to calculate the autosomal recessive disease risk of a fetus when one or no mutation is detected, and another, independent risk factor is present. Our methods are particularly useful for calculating the CF disease risk for a fetus with echogenic bowel. In genetics practice, however, there are other scenarios for which our previous methods are inadequate. METHODS AND RESULTS: We provide herein methods for calculating genetic risks in a variety of common clinical scenarios. These scenarios include the following: (1) different mutation panels that have been used for the parents and for a fetus; (2) genetic testing results available on the proband or other relatives, in addition to the consultand; (3) fetal ultrasound negative for echogenic bowel with a positive family history; and (4) a consultand with a mixed ethnic background. CONCLUSION: Our Bayesian methods have proven their versatility through application to many different common genetic counseling scenarios. These methods permit autosomal recessive disease and carrier probabilities to be calculated accurately, taking into account all relevant information. Our methods allow accurate genetic risk estimates for patients and their family members for CF or other autosomal recessive disorders.

Bayes Theorem↗
PubMedDate not supplied

Risk calculations for cystic fibrosis in neonatal screening by immunoreactive trypsinogen and CFTR mutation tests.

PURPOSE: Although neonatal screening (or newborn screening) for cystic fibrosis (CF) is commonly practiced, systematic methods for accurate risk calculations are currently lacking. METHODS AND RESULTS: We evaluated characteristics of the immunoreactive trypsinogen (IRT) test using the published data. The probability that a neonate has a positive IRT test, if the neonate is affected, a carrier, or a noncarrier, is approximately 1, 0.041, or 0.011, respectively. We provide methods to calculate genetic risks for a variety of commonly encountered scenarios in which neonates are positive by the IRT test. CONCLUSION: Our Bayesian methods permit CF disease probabilities to be calculated accurately, taking into account all relevant information.

Bayes Theorem↗
PubMedDate not supplied

Technical standards and guidelines: venous thromboembolism (Factor V Leiden and prothrombin 20210G >A testing): a disease-specific supplement to the standards and guidelines for clinical genetics laboratories.

These standards and guidelines are designed primarily as an educational resource for clinical laboratory geneticists to help them provide quality clinical laboratory genetic services. Adherence to this statement does not necessarily ensure a successful medical outcome. These standards and guidelines should not be considered inclusive of all proper procedures and tests or exclusive of other procedures and tests that are reasonably directed to obtaining the same results. In determining the propriety of any specific procedure or test, the clinical molecular geneticist should apply his or her own professional judgment to the specific clinical circumstances presented by the individual patient or specimen. It may be prudent, however, to document in the laboratory record the rationale for any significant deviation from these standards and guidelines.

Factor V↗