CGS Research Project Descriptions
I. SEGREGATION ANALYSES, GENETIC LINKAGE STUDIES AND POSTIONAL CLONING OF GENES ASSOCIATED WITH INHERITED HUMAN DISEASES AND SUSCEPTABILITIES
1) The Genetics of Hereditary Craniofacial Dysmorphologies and Related Syndromes
This program began in 1992 as a collaborative project between the future founders and directors of the Cellular for Genomic Sciences (CGS), Drs. J. Christopher Post and Garth Ehrlich, and has been awarded NIH funding for 17 years to date. Published works from this project include manuscripts in Gene, Nature Genetics and Human Molecular Genetics as well as invited talks at national and international meetings. This project began with the mapping by Dr. Robert Preston and cloning of the gene (FGFR2) for Crouzon syndrome and Jackson-Weiss Syndrome (Gorry, et al). These observations turned out to be a watershed event in the field of craniofacial dysmorphologies and within months, five other craniofacial syndromes had been mapped to FGFR2 or other FGFR genes. Based on this synergy, CGS hosted a world-wide symposium in Pittsburgh to bring together the research community in craniosynostoses.
CGS research led to the elucidation of the entire genomic structure of the FGFR2 gene with DNA sequence available for all intron-exon boundaries and a comparison with other FGFRs in human and mice. This was accomplished using a combination of genomic library screening, long-PCR, and automated DNA sequencing. Ongoing studies are designed to further characterize the promoter and enhancer elements of the FGFR2 gene. Preliminary data indicates control elements as far as 7 kb 5′ of the transcription start site as well as tissue-specific positive and negative cis-acting regulatory elements.
Together with our collaborator, Dr. Michael Cunningham (University of Washington, Seattle), we have developed a chimeric xenotransplant small animal model (nude rat) that faithfully recapitulates the cardinal features of craniosynostosis. We are currently exploiting this model to study the downstream effects of the dominant gain of function mutations associated with the point mutations in FGFR2 by screening sutural expressomes from normal and induced synostotic coronal sutures.
We are also investigating whether FGFR2 mutant osteoblasts can be used therapeutically to promote bony growth in cases of nonunion. (ENT, Plastic Surgery, Orthopedics, Pathology, Human Genetics)
2) The Genetics and Biochemistry of Hereditary Pancreatitis (HP)
This program was begun by Dr. Ehrlich in 1995 with the concept of identifying the genetic cause of HP. We successfully assembled the kindreds, mapped the gene to chromosome 7q, cloned the cationic trypsinogen gene as the cause of the disease, and constructed a theoretical model to explain the disease symptoms in less than one year. This work was highly editorialized, and the NIDDK held press releases about the importance of these discoveries and reported it to the United States Congress in their annual review. This work has resulted in over a dozen publications (including three rapid publications in Nature Genetics and Gastroenterology) and presentations around the world. Based upon the discoveries resulting from this work, CGS hosted an international meeting on the genetics of pancreatitis which was attended by scientists across the North American Continent and from Asia and Europe. The President of West China University of the Medical Sciences visited CGS to learn more about our HP work. (Gastroenterology, Surgery)
3) The Genetics of Vesicoureteral Reflux (VUR)
This project was begun as a collaboration between the CGS directors and Dr. Francis Schneck (University of Pittsburgh) in 1995 and was directed by Dr. Robert Preston. In addition, CGS has collaborated with a group headed by Dr. Mike Eccles in New Zealand with whom Dr. Ehrlich had previously worked on the construction of physical maps of human chromosome 10. This project is designed to physically map major genes for VUR. At this juncture in spite of having assembled several large families and some 40 sib pairs, no single locus has been unambiguously identified after performing multiple gene scans suggesting that the genetics may be quite complex and heterogeneous. (Pediatric Urology, Human Genetics)
4) The Genetics of Diffuse Abnormal Insertional Activity
This project was initiated in 1994 by Dr. Ehrlich in collaboration with Drs. Giuliani and Hurtt at the University of Pittsburgh. Dr. Giuliani had realized that several members of a family had the same abnormal EMG results. Dr. Hurtt prepared a pedigree which revealed an AD pattern of inheritance in a three generation family. IRB approval was obtained and bloods were collected from all affected and unaffected family members for DNA preparations. A genome-wide scan using microsatellite markers was performed and genetic linkage analyses revealed a single locus which demonstrated co-segregation with the phenotype through the family. This project is ready for a major NIH grant application. (Neurology, Neuropathology)
5) The Genetics of Hereditary Severe Infantile Gastroesophageal Reflux (GER)
This is a major project undertaken by CGS beginning in 1998. Dr. Post initially realized through his clinical ENT practice (Allegheny Pediatric ENT Associates) that severe pediatric GER was familial. His observations were in concordance with those of the GER patient support group (Pediatric/Adolescent Gastroesophageal Reflux Association) and this synthesis of ideas resulted in the establishment of a collaborative project between CGS and PAGER Directors, Beth Anderson and Caroline McGraw. In addition, we have established collaborations with pediatric gastroenterologist, Dr. Thomas Self and Dr. Ramamurti Chandra. This disorder is quite possibly the most common autosomal dominant disease of mankind, affecting >2% of all children. The laboratory aspects of this project, directed by Dr. Robert Preston and Dr. Fen Hu, included the performance of a genome-wide scan on a large family which resulted in the establishment of linkage to chromosome 13q14. These results were subsequently confirmed with several additional GER families and we obtained a multipoint, multifamily LOD of greater than 7. This work has been published in JAMA and Human Molecular Genetics. We are currently in the midst of a large-scale positional cloning effort and have to date identified over novel 150 SNPs within the linkage region which are being further analyzed. An NIH R01 supporting this work was funded as of July 1, 2000. (Pediatric GI, Pediatric ENT)
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6) Genes that make Humans Human
Drs. Ehrlich and Post have had a longstanding interest in genes associated with language development and cognition as it is this aspect of our behavior as a species which is uniquely human. To this end CGS scientists have been working for the past several years with Dr. Thomas Campbell of Children’s Hospital of Pittsburgh (CHP) to identify suitable study populations for genetic mapping projects. Recently, we have also added Dr. Larry Schrieber to our collaborative group and the three groups plan to apply for joint NIH funding in the future. Drs. Campbell and Schrieber are recognized as two of the premier phenotypers for language and speech disorders in the world today and Dr. Campbell, as Director of the Audiology and Speech Communications Department at CHP, has thousands of children in his clinical practice, many of whom who are already in study protocols. Drs. Ehrlich, Post and Schreiber were all invitees of the NIH’s NIDCD in 1997 to be part of a blue-ribbon panel that was charged with assessing whether or not the technology and phenotyping had progressed to the point where it was realistic to begin using genetic mapping methodologies to identify candidate loci for behavioral traits associated with communication. We have chosen apraxia of speech as our first target in this area and are working with the national patient support group to obtain individuals for phenotyping and genetic testing. (Audiology and Speech Communications)