Signs and Symptoms of Genetic Conditions A Handbook PDF
4.63 MB PDF
Preface
The goal of this book is to provide a clear and concise approach to the various clinical features encountered in an individual for whom a genetic diagnosis is being considered. Our hope is that this approach will be helpful to any care provider. We have successfully used this approach in the education and training of the many residents in medical genetics and other specialties, medical students, and graduate students with whom we have had the privilege to work.
Even though this book is being published in 2014, the reader will note that we do not recommend whole-exome (WES) or whole-genome sequencing (WGS) for every patient. First of all, this new technology is not indicated for all patients with a suspected genetic disorder. As described in the chapter on testing, WES/WGS does not identify chromosome abnormalities including microdeletions or duplications; trinucleotide repeat disorders; conditions that are caused by abnormal imprinting or epigenetic modification; and mosaicism for single gene mutations. These limitations probably contribute to a current detection rate of ~25–40% for WES/WGS. Secondly, WES/ WGS does not identify all single gene mutations, because of the current limitations of the technology and interpretation of the data. Thirdly, some genetic conditions are truly multifactorial—that is, caused by both mutations in more than one gene (polygenic) and environmental influences. Finally, and very importantly, WES/WGS is not currently available for all patients and providers, most often due to its cost and limitations in insurance coverage.
We have asked valued and trusted colleagues to contribute each chapter. The authors describe their approach to the evaluation of a particular finding, often in a stepwise fashion in order to limit the number of procedures and tests performed. Each chapter includes at least one flow chart illustrating this approach.
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