We apply functional genomics and related technologies to the study of regulatory mechanisms in both normal development and disease processes. To understand the network of genes and the various biological processes underlying germ cell development, we mapped the transcriptome of mouse germ cells at different stages of spermatogenesis. Biochemical, genetic, and computational analyses of germ cell transcriptomes identified novel genes and biological processes that are stage-specific regulatory mechanisms or either specific for or prominent in germ cells. Mapping the transcriptome of the embryonic gonad at different stages of development should provide information about genetic regulation during early gonad development. Parallel studies include investigations into the molecular etiology of testicular tumors and prostate cancers. Collateral to investigation of the behavioral effect of an inactivating luteinizing hormone receptor (LHR), we identified a novel role of the receptor in neuronal development. We also study patients with a variety of genetic and metabolic disorders, thereby providing clinical genetics training opportunities. In one such protocol, we identified the role of susceptibility to thrombosis in the etiology of the pseudotumor cerebri of nephropathic cystinosis. Our work has led to a unique approach to screen for combinations of polymorphisms in a number of venous thrombosis–related molecules.
Computational analyses and functional genomic studies of mouse germ cells
Lee, Alba, Rennert, Chan
One of our goals is to understand the intricate regulatory mechanism of cellular proliferation and differentiation as well as the development-specific mechanisms of gene expression and to identify genes that play critical roles in meiosis and differentiation. To that end, we have mapped the transcriptome of mouse germ cells at three critical stages of spermatogenesis, namely, type A spermatogonia at mitosis, pachytene spermatocytes at meiosis, and round spermatids at post-meiotic differentiation. During the past year, we applied various computational and biochemical analyses to annotate functional elements and to identify the interacting molecules of expressed gene products. By applying unsupervised hierarchical clustering, we identified genes represented by SAGE (sequential analysis of gene expression) tags preferentially expressed at different stages of germ cell development and analyzed the promoter elements of the clustered genes and the biological processes represented in each cluster. Based on the ontology of clustered genes, including ribosome biogenesis and assembly, the integrin signaling pathway, carbohydrate metabolism, protein biosynthesis, and RNA processing, we found 36 biological processes that are overrepresented in spermatogonia; 21 gene-ontology categories overrepresented in pachytene spermatocytes; and 26 enriched gene-ontology categories mainly related to cellular physiological process and metabolic process associated with the ubiquitin cycle, proteolysis, and peptidolysis. Besides the known transcription regulators such as NF-kappaB, SP1, AP-1, and EGR, we observed novel promoter elements such as E-box in spermatogonia genes, GATA in spermatocyte genes, and Gut-enriched Krueppel-like binding factor site in spermatid genes. To visualize the relationship among the clustered genes, we constructed potential biological networks linking the gene candidates with neighboring genes, proteins, transcription factors, and small molecules. The exercise allowed the identification of in silico targets for regulating spermatogenesis and the generation of representative “signature networks” essential for specific stages of spermatogenesis. The results will provide a foundation for further in vitro and in vivo studies of germ cell development.
Wu SM, Baxendale V, Chen Y, Li X, Pang ALY, Stitely T, Munson PJ, Leung MYK, Ravindranath N, Dym M, Rennert OM, Chan WY. Analysis of mouse germ cell transcriptome at different stages of spermatogenesis: biological significance. Genomics 2004;84:971-981.
Liu Y, Yao ZX, Bendavid C, Borgmeyer C, Han Z, Cavalli LR, Chan WY, Folmer J, Zirkin BR, Haddad BR, Gallicano I, Papadopoulos V. Haploinsufficiency of cytochrome P450 17alpha-hydroxylase/17,20 lyase (CYP17) causes infertility in male mice. Mol Endocrinol 2005;19:2380-2389.
Chan WY, Lee TL, Wu SM, Alba D, Baxendale V, Rennert OM. Transcriptome analyses of male germ cells with SAGE. Mol Cell Endocrinol 2005 (in press).
Characterization of stage-specific alternative 3´ end usage in male germ cells
Lee, Pang, Alba, Rennert, Chan
Although alternative splicing plays an important role in modulating gene function, little is known about its regulatory mechanisms, particularly with respect to stage specificity and how it is achieved. Recognizing that the generation of germ cell SAGE libraries offered a unique opportunity to study stage-specific alternative splicing, we performed a systematic search for transcript variants with alternative 3´ end usage. To retrieve the unigene clusters, we mapped unique SAGE tags at each stage to SAGEmap and compared any tags sharing the same unigene cluster within or among the stages with different alternative splicing resources; we validated the tags by RT-PCR. In spermatogonia, 74 genes had 3´-end alternative splicing variants (3´ ASV). Similarly, 58 and 62 genes had 3´ ASV in spermatocytes and spermatids, respectively. We also found genes with different 3´ ASV in two cell stages: 207 genes with 3´ ASV expressed in spermatogonia and spermatocytes, 249 genes with 3´ ASV in spermatogonia and spermatids, and 158 genes with 3´ ASV in spermatocytes and spermatids. We found 73 genes that produced different 3´ ASV specific to each cell stage, including novel variants of genes involved in developmental and transcriptional controls, such as those encoding heat shock protein 4 (Hsp4), H3 histone family 3B (H3f3b), and ubiquitin protein ligase E3A (Ube3a). Studies are under way to identify the mechanism that regulates stage-specific splicing and the function of the different 3´ alternative slicing of selected genes.
Antisense transcription in differentiating germ cells
Wu, Ruszczyk, Law,1 Horvath, Rennert, Chan
Although it has been known for many years that antisense transcription occurs in prokaryotes, the literature has only recently documented the widespread occurrence of antisense transcripts in humans and mice. Several processes in spermatogenesis such as genomic imprinting, translation repression, stage-specific alternative splicing, and so forth are frequently associated with antisense transcripts. However, a systematic search for antisense transcripts in spermatogenic cells has not been reported. Mapping of the transcriptome of mouse germ cells by SAGE offers a unique opportunity to examine the occurrence of antisense transcription during spermatogenesis. Using orientation-specific RT-PCR and nucleotide sequencing, we showed that 19 of 64 differentially expressed genes have antisense transcripts. They arose through a variety of mechanisms, including transcription of the sense mRNA in the cytoplasm, transcription of the opposite strand of the sense gene locus, transcription of a pseudogene, or transcription of neighboring genes and the intergenic sequence. Expression studies of the sense and antisense transcript of nine genes (Uba52, Calm2, Ppp1cc, Ppic, Tsg1, Tcte3, Pdcl2, Prm 1, and Prm2) showed that the testicular levels of the sense transcripts were higher than those of the antisense transcripts while the relative distribution of the transcripts in nontesticular tissues varied. The study showed that antisense transcription was prominent among germ cell genes.
To investigate the interaction between the sense and antisense transcripts, we examined the expression of the sense and antisense transcripts of 17 genes in nine mouse cell lines derived from spermatogonia, Sertoli cells, Leydig cells, kidney, spleen, and liver; we confirmed expression of antisense transcripts of 10 genes in the cell lines, which we will use as in vitro models for studying the functional activities of the cloned antisense transcripts of the 10 genes.
Regulation of expression and functional role of mLin28 in male germ cell development
Pang, Bear, Rennert, Chan
Lin28 is known to be a heterochronic gene that regulates developmental timing in C. elegans. A defective Lin28 results in precocious larval stage progression while overexpression leads to retarded development resulting from reiteration of the earlier larval stage. We hypothesized that the mouse Lin28 homologue (mLin28) would have a similar role in regulating the decision between germ cell proliferation and differentiation. To this end, we are delineating the mode of regulation of mLin28 expression at both transcriptional and post-transcriptional levels. By performing RACE experiments, we observed a differential use of transcription start sites of mLin28 transcripts as germ cells differentiate. Using promoter element prediction algorithms, we identified specific promoter elements and modules known to activate transcription. We are now assaying promoter activity to verify the computational data and to identify any unknown or potentially germ cell–specific protein factors that would be involved in the gene transcription event. In similar experiments, we analyzed the 3´ end of mLin28 transcripts and found that they were heterogeneous: alternative 3´ ends of the transcripts displayed stage-specific expression patterns. We also observed both canonical and unconventional polyadenylation signals. We hypothesize that specific fragments of the mLin28 3´untranslated region (UTR) are involved in modulating the translation of the encoded protein. Specifically, we predicted the presence of potential binding sites for a subset of microRNAs and other regulatory factors on the 3´ UTR. We are now testing the relationship between the elongation/shortening of the 3´ ends and the gain/loss of modulation. We expect that the elucidation of these regulatory pathways will explain the testis-specific and spermatogenic stage-specific expression pattern of mLin28 at the genetic level.
Regulation of expression and study of the functional role of mArd2 during spermatogenesis
Pang, Peacock, Bear, Rennert, Chan
We cloned a novel mArd1 homologue, which we named mArd2, that demonstrated testis specificity and elevated expression in pachytene spermatocytes. The mArd1 protein is known to interact with an auxiliary protein subunit mNAT1 to constitute a functional N-acetyltransferase. Earlier studies in yeasts identified a diverse role for ARD1 from cell cycle regulation to DNA repair and recombination. We observed a delay in the expression of mArd2 protein with respect to the transcript expression pattern. Interestingly, both mLin28 and mArd2 transcripts carried very long 3´ UTRs. We hypothesize that the repression of mArd2 protein expression is related to the presence of regulatory elements on the 3´ UTR of the transcripts. Accordingly, we identified several regulatory elements known to mediate a translational repression effect on the 3´ UTR of mArd2. We also identified potential microRNA-binding sites present on the mArd2 3´ UTR. We will use methods similar to those used for mLin28 to determine the mechanism of regulation of mArd2 expression. To correlate the spatial/temporal requirements of the enzymatic activity in the context of germ cell development, we are also testing the potential interaction between all known mouse Ard1 and NAT1 homologues as well as their expression patterns. Further experiments are planned to elucidate the functional role of mArd2.
Pang ALY, Johnson W, Dym M, Rennert OM, Chan WY. Expression profiling of purified male germ cells: stage specific expression patterns related to meiosis and post-meiotic development. Physiol Genomics 2005 [Epub ahead of print].
Functional genomic studies of gonad development and sexual dimorphism of the brain
Baxendale, Alba, Lee, Vong,2 Bear, Rennert, Chan; in collaboration with Lau
To understand the mechanisms that regulate the transition of primordial germ cells to gonocytes and the initiation of sexual dimorphism, we used SAGE to profile the genes expressed in male and female embryonic gonads at E10.5 (embryonic day 10.5), E11.5, E12.5, E13.5, E15.5, and E17.5 and in the mesonephros at E13.5, E15.5, and E17.5. We completed the analysis of about 152,000 SAGE tags for each of the male E10.5, E11.5, E12.5, and E17.5 gonads. The 10 most abundant tags are Cypb cytochrome b-245, beta polypeptide, Cyp2e1 cytochrome P450, COX5b, Tctp1 (translationally controlled tumor protein), Hbb-y (hemoglobin Y), beta-like embryonic chain, Tuba2 tubulin, alpha 2, 4 ribosomal proteins (X-linked S4, L26, 29, and L10A), and one uncharacterized cDNA. Among the 10 most abundant tags present in embryonic gonads and absent from germ cells are four genes encoding hemoglobin chains, namely, Hba-X, Hbb-b1, Hbb-Y, and Hba-a1. The role of hemoglobin genes in early embryonic gonad development is not yet understood, although a recent paper examining gene expression in embryonic lens demonstrated the expression of hemoglobin isoforms (Hba-a1, Hba-X, Hbb-b1, Hbb-b2, and Hbb-Y). These preliminary observations have important implications for understanding the regulation of gonad development and germ cell differentiation. We are continuing to analyze expressed genes in male gonads at later embryonic ages and in female gonads and mesonephros.
Sexual dimorphism is known to occur in the brain, but the time of divergence is poorly understood. A better understanding of the relationship between brain and gonad development may yield insights into the cause of gender differences in development. Using Affymetrix oligonucleotide gene chips, we profiled expressed genes in paired gonad and brain samples at different embryonic days (E10.5, E11.5, E12.5, E13.5, E15.5, and E17.5). We also generated human cDNA sex-linked gene microarrays of 724 X-linked and 28 Y-linked human genes on glass slides and will use the microarrays to profile expressed genes in the brain and gonad of male and female mice (at E10.5, E13.5, E15.5, and E17.5; in newborn mice; and in adult mice), comparing the expression profile of male and female brains and gonads at different time points.
Epigenetics of testicular germ cell tumors
Lee, Alba, Rennert, Chan; in collaboration with Huang, Lau, Mosca
We set out to examine the global epigenetic alteration in human tumors, particularly testicular germ cell tumors (TGCT). Even though seminoma and non-seminoma testicular germ cell tumors (TGCT) share similar regional genomic disruptions, recent studies of the two tumor types suggested different epigenotypes. CpG island methylation is virtually absent in seminomas while the methylation level in non-seminomas is similar to that of other solid tumors. Despite the literature’s reports of aberrant methylation of genes, including CDKN2A, RUNX3, and MGMT, the global picture of epigenetic alteration remains unclear with respect to gene function category, expression pattern, and prevalence in the TGCT genome. To study the global epigenetic alteration in TGCT, we examined the methylation profile of several testicular cancer cell lines by using oligonucleotide-based methylation microarrays. We have collected a number of testicular tumor tissue samples, including archived frozen or paraffin samples of nonseminomas, seminomas, carcinoma in situ, as well as normal testis tissue samples. To improve the molecular classification of TGCT and facilitate the discovery of specific biomarkers for early detection, we plan to perform epigenetic and global expression profiling on tumor cells by using Laser Capture Microdissection. For the epigenetic profiling, we will perform DNA hybridization with oligonucleotide-based methylation microarray and use RNA for expression profiling on an Affymetrix platform, followed by bisulfite sequencing/methylation-specific PCR and real-time RT-PCR to validate methylation and expression data from the arrays.
Role of the TSPY-1oncogene in prostatic and testicular cancers
Lee, Pang; in collaboration with Lau
Y-encoded gene (TSPY), which encodes testis-specific Y protein, has been mapped to the vicinity of the gonadoblastoma (GBY) locus on the Y chromosome and is considered a candidate gene for GBY. TSPY is expressed in normal spermatogonia and carcinoma in situ of the testis. Recently TSPY has been shown to express aberrantly in tumor epithelial cells in prostate cancers of low and high Gleason grades. We aim to understand the genetic role of TSPY. We examined HeLa cells harboring either a stably integrated TIG-TSPY or TIG vector and, using the Significant Analysis of Microarrays, analyzed differential gene expression between the transfectant and the control. We identified the biological processes represented by the differentially expressed genes and used Gene Ontology Tree Machine (GOTM) to analyze the ontology of the genes. The results showed alterations in three specific processes, i.e., cell cycle regulation, phosphate transport, and neuromuscular development. Among the genes upregulated by the expression of TSPY were several oncogenes (epidermal growth factor receptor [ERBB] and members of the WNT and RAS oncogenes), growth factors (PDGFC, EGF-related, ANKRD15, RGC32, and NANOS1), cyclin D2 (CCND2), a co-factor for the hypoxia-inducible factor 1A (p300), an apoptosis inhibitor (GSPT1), and an antigen (CD24) highly expressed in small cell lung carcinoma. The downregulated genes included CDK4/CDK6, transforming growth factor b3 (TGFb3), a pro-apoptotic factor (IGFB3), and an inhibitor of MAP kinases. Notably, the CCND2 gene resides on chromosome 12p, which is frequently amplified and expressed at high levels in TGCTs. CCND2 complexes with CDK4 or CDK6 to mediate G1/S transition and promote cell proliferation. The preliminary data suggest that TSPY could be an oncogene in male-specific tissues.
Ifon ET, Pang ALY, Johnson W, Cashman K, Zimmerman S, Muralidhar S, Chan WY, Casey J, Rosenthal LJ. U94 alters FN1 and ANGPTL4 gene expression and inhibits tumorigenesis of prostate cancer cell line PC3. Cancer Cell Internat 2005;5:19.
Nalbandian A, Pang ALY, Rennert OM, Chan WY, Ravindranath N, Djakiew D. A novel role of differentiation revealed by cDNA microarray profiling of p75NTR-regulated gene expression. Differentiation 2005;73:385-396.
Ohta S, Lai EW, Pang ALY, Brouwers FM, Chan WY, Eisenhofer G, de Krijger R, Ksinantova L, Blazicek P, Breza J, Kvetnansky R, Wesley RA, Pacak K. Down-regulation of metastasis suppressor gene in malignant pheochromocytoma. Internat J Cancer 2005;114:139-143.
Horvath A, Mathyakina L, Vong Q, Baxendale V, Pang ALY, Chan WY, Stratakis C. Serial analysis of gene expression (SAGE) of the human adrenal gland: normal tissue and adrencortical hyperplasia caused by a germline PRKAR1A mutation. J Clin Endocriol Metab 2005 (in press).
Biochemical effect of an inactivating mutation of the luteinizing hormone receptor
Leung,3 Bear, Wu, Rennert, Chan; in collaboration with Fechner, Steinbach
Luteinizing hormone/chorionic gonadotropin receptor (LHR) plays a key role in the development of the gonad and in reproductive physiology. In the testis, inactivation of the LHR results in reduced production of testosterone and causes hypergonadotrophic hypogonadism in Leydig cell hypoplasia (LCH), a form of male pseudohermaphroditism. A novel missense mutation A340T identified in a patient with LCH resulted in the substitution of Phe for Ile-114. Phe affects one of the leucine-rich repeats (LRR) in the extracellular domain of the hLHR. In transient expression studies, the mutant receptor fails to trigger cAMP production upon hCG stimulation. As revealed by fluorescent microscopic study of the fusion protein of the receptor with green fluorescent protein, the mutation apparently does not affect trafficking of the mutated receptor but rather binding of the hormone to the receptor. Computer modeling of LRR confirmed the conformational effect of the mutation and may explain the impact of mutations on the biological activity of other proteins with LRRs.
Chan WY. Disorders of sexual development caused by luteinizing hormone receptors. Beijing Da Xue Xue Bao (Hlth Sci) 2005;37:32-38.
Leung MY, Al-Muslim O, Wu SM, Azizs A, Inam S, Awadh M, Rennert OM, Chan WY. A novel missense homozygous inactivating mutation in the fourth transmembrane helix of the luteinizing hormone receptor in Leydig cell hypoplasia. Amer J Med Genet2004;130A:146-153.
Salameh W, Shoucair M, Guo TB, Zahed L, Wu SM, Rennert OM, Chan WY. Leydig cell hypoplasia due to inactivation of luteinizing hormone receptor by a novel homozygous nonsense truncation mutation in the seventh transmembrane domain. Mol Cell Endocrinol2004;229:57-64.
Novel function of luteinizing hormone/chorionic gonadotropin receptor (LHR) in the nervous system
Meng, Rennert, Chan
Individuals whose LHRs carry activating mutations develop familial male-limited precocious puberty (FMPP) and often exhibit behavioral problems, which we believe may be the consequence of an activated luteinizing hormone (LH) signaling pathway. Recently, LHR expression was demonstrated in several non-gonadal tissues, including the nervous system. In the brain, the LHR expression level is developmentally regulated, and others have detected LHR expression in some neurons of specific brain regions of the adult rat, namely, the ependymal cells of all four ventricles and the choroid plexus. In our effort to investigate the functional activity of LHR in the brain, we transfected the mouse neuronal cell line PC12 with an expression construct containing the human LHR cDNA (hLHR) carrying the activating mutation Asp578His (H mutation) for insertion into pIRES2EGFP under the control of CMV promoter. Transfection with the mutated hLHR led to three times as much neurite outgrowth as in cells transfected with the vector alone or with wild-type hLHR. Among the neurite-bearing cells, in about twice as many of those transfected with the mutated LHR, the neurites became twice as long as the cell body compared with cells transfected with vector or wild-type hLHR, suggesting neurotrophic effects of hLHR in the brain. Further experiments are under way to elucidate the mechanism of LHR-induced neuronal differentiation.
Role of susceptibility to thrombosis in the pseudotumor cerebri of nephropathic cystinosis
Dogulu, Raygada, Chan, Rennert; in collaboration with Gahl, Kaiser
Given our findings regarding genetic susceptibility to thrombosis in pseudotumor cerebri (PTC), we are studying the role of thrombosis in the development of PTC in nephropathic cystinosis. We are screening nephropathic cystinosis patients who develop PTC and control nephropathic cystinosis patients without PTC by using a thrombosis susceptibility panel, including prothrombin time (PT), activated partial thromboplastin time (aPTT), thrombin time (TT), activated protein C resistance (APCR), serum levels of protein C and S, antithrombin III, fibrinogen, total homocysteine, and antiphospholipid antibodies (anticardiolipin [ACA] panel and Lupus AC). In patients with severe homocysteinemia (>100 micro mol/l), we are also screening for FV Leiden mutation, FV G1628A polymorphism, FV R2 allele, Prothrombin 20210 mutation, and 5,10-methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism. To date, we have recruited five patients with pseudotumor cerebri with pre-existing nephropathic cystinosis. The thrombosis screening panel revealed shortened thrombin time (TT) in two patients, high-titer ACA IgM antibodies in one patient, and APCR in another patient. TT measures the rate of fibrin monomer polymerization and is the most sensitive screening test for decreases or abnormalities in fibrinogen. The shortened TT demonstrates an acceleration of fibrin monomer polymerization leading to a thrombotic tendency. APCR resistance is a condition that leads to a hypercoagulable state with an increased risk for venous thrombosis, and we have shown that an IgM isotype of ACA is associated with venous thrombosis.
Dogulu C, Tsilou E, Rubin B, Fitzgibbon E, Kaiser-Kupper M, Rennert O, Gahl W. Idiopathic intracranial hypertension in cystinosis. J Pediat 2004;145:673-678.
Assessment of hereditary thrombophilia
Dogulu, Chan, Rennert; in collaboration with Su
Venous thrombosis affects one in 1,000 individuals annually and is one of the leading causes of mortality and morbidity, resulting in approximately 300,000 hospitalizations and 50,000 fatalities per year in the United States alone. It is, however, an avoidable disease if currently available prophylactic treatment is instituted. To develop stratification protocols for risk-adapted prophylaxis, we have devised an approach termed a method evolved for recognition of thrombophilia (MERT) (patent pending) that will allow prediction and accurate assessment of hereditary thrombophilia in several ethnic populations by rapid, concurrent screening of an array of all known 143 venous thrombosis–associated recurrent mutations and polymorphisms in eight genes.
Clinical protocol in studies of pediatric patients with genetic and metabolic disorders
Raygada, Dogulu, Rennert; in collaboration with Kaler, Stratakis
The aim of our clinical protocol is to provide care for patients with a variety of rare genetic disorders and to supplement and offer an additional opportunity for training in clinical genetics, dysmorphology, and metabolic genetics in NICHD and other institutes of the NIH. We evaluate patients with a broad spectrum of metabolic and genetic conditions; at present, 386 patients are under the protocol. We also offer genetic counseling services to patients and their families to assess risk and provide information on preventive measures and testing options. We study chromosomal and Mendelian disorders of childhood and/or adult onset, congenital anomalies and/or birth defects, dysmorphic syndromes, familial cancer syndromes, multifactorial disorders, and metabolic abnormalities. If not eligible for another NICHD research protocol (specific for a disease or a treatment), patients with genetic/metabolic-related conditions may be evaluated under the auspices of this protocol to provide stimuli for clinical research initiatives. Standard, medically indicated laboratory or radiological studies may be performed to confirm a diagnosis or to aid in the management of the patient. In some cases, patients receive medical or surgical treatment for their disorder, according to current clinical practice. Patients and/or family members with genetic disorders may offer their DNA for storage and/or testing.
Corrigan EC, Raygada MJ, Vanderhoof VH, Nelson LM. A woman with spontaneous premature ovarian failure gives birth to a child with fragile X syndrome. Fertil Steril 2005;84:1508.
Raygada M, Rennert OM. Congenital generalized lipodystrophy: profile of the disease and gender differences in two siblings. Clin Genet 2005;67:98-101.
Stratakis C, Rennert OM. Turner syndrome: an update. The Endocrinologist 2005;15:27-36.
1Evelyn Law, BS, former Summer Medical Student
2Queen P. Vong, PhD, former Postdoctoral Fellow
3Michael Y.K. Leung, PhD, former Postdoctoral Fellow
COLLABORATORS
Patricia Fechner, MD, Stanford University, Palo Alto, CA
William Gahl, MD, PhD, Clinical Director, NHGRI, Bethesda, MD
Tim H.M. Huang, PhD, University of Missouri, Columbia, MO
Muriel I. Kaiser, MD, Ophthalmic Genetics and Visual Function Branch, NEI, Bethesda, MD
Steven G. Kaler, MD, MPH, Laboratory of Clinical Genomics, NICHD, Bethesda, MD
Chris Y.F. Lau, PhD, University of California San Francisco, San Francisco, CA
Phil Mosca, MD, PhD, Southwest Medical Center, Oklahoma City, OK
Peter Steinbach, PhD, Center for Information Technology, NIH, Bethesda, MD
Timothy Stitely, MS, Unit on Computer Support Services, NICHD, Bethesda, MD
Constantine Stratakis, MD, DSc, Heritable Disorders Branch, NICHD, Bethesda, MD
Yan Su, MD, PhD, Loyola University, Chicago, IL
For further information, contact rennerto@mail.nih.gov.