On The Spot e-News
Volume 4, Issue 5 | May 2009
In this issue:
- Signature Scientific Microarray Conference Keynote Speakers
- Detection of Mosaic Partial Tetrasomy 12p Associated with Pallister-Killian Syndrome by aCGH
- Detection of Microdeletion/Microduplication Syndromes Associated with Cancer Susceptibility
Signature Scientific Microarray Conference Keynote Speakers Announced
The keynote speakers for the 2009 Signature Scientific Microarray Conference have been announced.
Keynote speaker R. J. McKinlay "Mac" Gardner, M.D., is co-author of the seminal cytogenetics text Chromosome Abnormalities and Genetic Counseling. For the past 14 years, Dr. Gardner has also been a consultant geneticist to Genetic Health Services Victoria, Royal Children's Hospital, Melbourne, Australia. Dr. Gardner received his M.D. from the University of Otago, Dunedin, New Zealand in 1968 and completed his training in clinical genetics in New Zealand, the U.K., France and Canada.
David Chitayat, M.D., is a Professor in the Departments of Pediatrics, Obstetrics and Gynecology, Molecular and Medical Genetics and Laboratory Medicine and Pathobiology. He is the head of the Prenatal Diagnosis and Medical Genetics Program at Mount Sinai Hospital, a clinical geneticist at the Division of Clinical Genetics and Metabolism, The Hospital for Sick Children and the Medical Director of The MSc Program in Genetic Counseling at the University of Toronto. Dr. Chitayat has contributed to over 200 publications in the fields of prenatal and pediatric pathology.
Kurt Benirschke, M.D., is a renowned expert in mammalian placental and reproductive pathology. Following a tenure as chairman of the Department of Pathology at Dartmouth Medical School, Dr. Benirschke helped establish the medical school of the University of California, San Diego (UCSD) in 1970. He has co-authored over five-hundred scientific publications and thirty books, including the Atlas of Mammalian Chromosomes and Human Placental Pathology. Dr. Benirschke is a member of numerous professional societies, including the American Academy of Arts and Sciences. Dr. Benirschke received his M.D. from the University of Hamburg, Germany.
Space at the conference is still available. If you are interested in participating in this unique opportunity to discuss the clinical applications of microarray technology with other geneticists in an intimate setting, please visit our conference webpage for more information.
Signature Genomic Laboratories Detects Chromosome Abnormalities in Individuals with Pallister-Killian Syndrome without Invasive Skin Biopsy
Geneticists at Signature have demonstrated that microarray-based genetic testing can identify a rare genetic disorder using DNA from blood rather than the more-invasive skin biopsy routinely used for testing.
Pallister-Killian syndrome (PKS) is a rare genetic disorder characterized by mental retardation, seizures, streaks of hypo- or hyperpigmentation and coarse facial features. PKS results from the presence of four, rather than the normal two, copies of the short arm of chromosome 12 in some of the body’s cells. The extra fragments of DNA usually cannot be identified in the cultured cells derived from blood used for conventional chromosome analysis, necessitating a painful skin biopsy for diagnosis. In their study, published in the May issue of the American Journal of Medical Genetics, geneticists at Signature reported eight individuals referred for testing for unexplained mental retardation or developmental delay in whom microarray analysis of uncultured DNA from peripheral blood identified a two-copy gain of the short arm of chromosome 12. In all but one individual, traditional cytogenetic analysis using cultured cells could not identify the abnormality, a discrepancy the authors attribute to the inability of abnormal cells to compete with normal cells during the culturing process required for conventional chromosome analysis. The authors suggest that, because it does not require cultured cells for analysis, microarray analysis can better detect chromosome abnormalities that are not present in every cell.
"These results show that microarray analysis can circumvent some of the inherent technical limitations of traditional chromosome analysis in the identification of abnormalities that are not present in every cell," said Dr. Lisa G. Shaffer, Ph.D., President and CEO of Signature and senior author of the study. "Furthermore, although Pallister-Killian syndrome is rare, individuals suspected to have the disorder can be tested using DNA derived from a simple blood draw rather than submit to a painful and invasive skin biopsy."
For more information about the detection of mosaicism by array CGH, please see our article "Detection of Low-Level Mosaicism by Array CGH in Routine Diagnostic Specimens" (request a reprint) in the American Journal of Medical Genetics.
Signature Genomic Laboratories Detects Chromosome Abnormalities in Individuals with Genetic Disorders Associated with Susceptibility to Cancer
Geneticists at Signature also recently demonstrated that microarray-based genetic testing can identify chromosome abnormalities that cause genetic disorders associated with susceptibility to cancer prior to the onset of symptoms.
In their study, to be published in the May issue of Genetics in Medicine , geneticists from Signature reviewed data from 18,437 individuals who were tested by microarray analysis for unexplained mental retardation and congenital anomalies. DNA copy number gains or losses that encompassed gene regions associated with recognized genetic conditions with an increased risk for cancer were identified in 34 individuals. Almost three-quarters of those individuals had indications for study that were not specific to the diagnosed syndrome and therefore presumably did not have signs of cancer. The authors describe multiple instances in which early diagnosis improved medical management of the patient and allowed for early surveillance of cancer onset.
"It is well known that microarray analysis allows for diagnosis of genetic syndromes at an early age that otherwise may not be diagnosed until onset of symptoms later in life," said Dr. Bassem A. Bejjani, M.D., Chief Medical Officer of Signature and senior author of the study. "However, this study shows the impact of early diagnosis is even more profound when a syndrome is associated with childhood-onset cancer, in which the threat of cancer is added to the child’s other medical issues."