The Publisher. Library of Congress Cataloging-in-Publication Data. Nussbaum, Robert L, —. Thompson & Thompson Genetics in Medicine. — 7th ed. Request PDF on ResearchGate | On Jan 1, , G. H. Sperber and others published Thompson and Thompson Genetics in Medicine. 7th edition. Through six editions, Thompson & Thompson's Genetics in Medicine has been a well-established favorite textbook on this fascinating and rapidly evolving field.
|Language:||English, Spanish, Portuguese|
|Genre:||Science & Research|
|Distribution:||Free* [*Registration Required]|
Thompson & Thompson Genetics in Medicine (Thompson and Thompson Genetics in Medicine) 8th Edition. by Robert L. Nussbaum MD FACP FACMG ( Author). Thompson & Thompson Genetics in Medicine: With STUDENT CONSULT Online Access (Thompson and Thompson Genetics in Medicine) 7th Edition. Thompson Genetics In Medicine 7th Edition nrmp program results main residency match - nrmp program results main residency match® .
Via either approach, chorionic villi are collected for genetic evaluation under ultrasound guidance without entering the amniotic sac. CVS allows for earlier prenatal diagnosis, subsequently decreasing time of uncertainty and allowing for earlier and, therefore, safer pregnancy termination if desired. Confined placental mosaicism may increase the risk of having a small-for-gestational-age infant.
It remains the only diagnostic test available in the second or third trimesters of pregnancy and may be performed at any gestational age after 15 weeks. Using this technique, a sterile needle is introduced into the amniotic sac under ultrasound guidance, and amniotic fluid is obtained and sent for testing.
In addition to evaluation for genetic disorders, amniocentesis may also be used to evaluate for presence of intra-amniotic or fetal infection via culture or polymerase chain reaction or for neural tube defects by measuring amniotic fluid alpha-fetoprotein and acetylcholinesterase.
Complications are more common at earlier gestational ages. Pregnancy loss attributed to amniocentesis is approximately 1 in on most recent estimates. However, some issues with cytogenetic testing have been identified that may limit the clinical utility of these methods. Mosaicism refers to tissue that contains 2 or more distinct cell lines. It is thought to reflect true mosaicism when multiple colonies from multiple cultures reveal the same results.
Pseudomosaicism refers to a single cell with a different genetic makeup than the others and is usually not clinically significant. Mosaicism may also arise in primary cell culture; when this occurs, it reflects pseudomosaicism rather than true mosaicism. As confined placental mosaicism also causes false-positive cell-free DNA results, amniocentesis is preferred over CVS for diagnostic testing in cases of positive cell-free DNA.
With some trisomies, particularly trisomy 15, a diploid fetus often arises secondary to trisomy rescue, which does increase the risk of uniparental disomy and subsequently increases risk of Prader-Willi and Angelman syndrome.
Cell culture failure also rarely occurs and is more common with sampling via CVS than with amniocentesis. Multiple testing methodologies are available, designed to detect different types of genetic abnormalities. Large deletions and duplications may be identified with karyotype in more than 5 million base pairs, whereas small deletions and duplications may be identified with microarray technology at as small as a 50, base pair level.
Single-gene disorders often require more targeted molecular approach to identify whether or not a particular mutation in a particular panel of genes is present or absent. As detection of aneuploidy is the most common indication for invasive testing, FISH is often the first test that is sent.
This technology does not require cell culture; thus, results are often available within 48 hours.
Despite that these results are obtained from a diagnostic procedure, these results should still be considered a screen and should be confirmed via karyotype given rare reports of both false-positive and false-negative results. Results can also be obtained from nonviable cells with this technique and, thus, may be more likely to result in cases of stillbirth. Given that microarray is able to detect both aneuploidy and smaller deletions and duplications with rapid turnaround, it is now recommended for evaluation of structural abnormalities as the initial testing strategy along with FISH, rather than conventional karyotype.
In these cases, parental studies are often considered to determine whether the variant is present in either parent. If so, it is more likely to be of little to no clinical significance. Given that 1. This procedure is performed after in vitro fertilization IVF by manipulation of the embryo to either remove a polar body or to remove a single cell from the blastocyst.
This procedure allows for detection of the abnormality before embryo transfer so that only unaffected embryos are transferred back.
Just as importantly, available options should be explained to patients and families in depth, most notably including the risks and benefits of each option, and how results might be reported. Patients who choose cell-free fetal DNA technology should be counseled that the test remains a screening test for aneuploidy at this time and that microdeletion testing continues to have poor positive predictive values due to the low prevalence of these disorders. It is not recommended that patients undergo more than one screening modality but rather that women who have positive screens and wish to pursue further testing be counseled on diagnostic testing with amniocentesis and CVS so as not to delay diagnosis.
Amniocentesis and CVS are increasingly safe with low rates of pregnancy loss and should continue to be available to all women who desire diagnostic testing regardless of risk factors or presence or absence of anomalies. Cell-free fetal DNA screening is currently recommended for high-risk populations only and should be considered a screening test rather than a diagnostic test. Chorionic villus sampling and amniocentesis carry a small but potential risk of pregnancy loss but remain the only diagnostic methodologies available presently.
Women should receive thorough pretest counseling regarding the risks and benefits of available options and should receive thorough posttest counseling with individualized interpretation of results. Footnotes Disclosure: The authors have no conflicts of interest to report. References 1. Annual summary of vital statistics: Practice bulletin No.
Obstet Gynecol. A randomized trial of prenatal versus postnatal repair of myelomeningocele.
N Engl J Med. Fetology: diagnosis and management of the fetal patient.
The diagnosis of sex before birth using cells from the amniotic fluid a preliminary report Bull Res Counc Isr. ACOG practice bulletin No. Fetal nuchal translucency: ultrasound screening for chromosomal defects in first trimester of pregnancy. Risk of selected structural abnormalities in infants after increased nuchal translucency measurement.
Am J Obstet Gynecol. Cardiac defects in chromosomally normal fetuses with increased nuchal translucency at 10—14 weeks of gestation. J Matern Fetal Neonatal Med. Increased nuchal translucency at 10—14 weeks of gestation as a marker for major cardiac defects. Ultrasound Obstet Gynecol. Lethal congenital arthrogryposis presents with increased nuchal translucency at 10—14 weeks of gestation.
Department of Health and Human Services. Chromosomal Basis of Heredity 2.
The Human Genome: Structure and Function of Genes and Chromosomes 3. Tools of Human Molecular Genetics 4. Principles of Clinical Cytogenetics 5. Clinical Cytogenetics: Disorders of the Autosomes and the Sex Chromosomes 6.
Mechanisms of Inheritance part I: Mendelian or Single-Gene Patterns 7. Mechanisms of Inheritance part II: Mitochondrial, Imprinted, and Multifactorial Patterns 8. Genetic Variation in Individuals and Populations 9. The Genetic Contribution to Disease: Locating and identifying Disease Genes Principles of Molecular Disease: Lessons from the Hemoglobinopathies The Treatment of Genetic Disease Genetics of Cancer Genetic Counseling and Risk Assessment Molecular Diagnostics