CME : Your SA Journal of CPD - Volume 23, Issue 1, 2005
Volume 23, Issue 1, 2005
Author Raj RamesarSource: CME : Your SA Journal of CPD 23, pp 8 –11 (2005)More Less
Arrival of humankind on earth has been marked by adventurous explorations in many different directions; many of these journeys have been against incredible odds. <br>Collectively, the advances have placed humankind on the pile of technological society, which continues to rise at a remarkable rate. <br>The macroscopic discoveries and inventions have been matched by remarkable and innovative means of microscopic resolution and imaging. <br>The Human Genome Project, which started off as a fairly limited journey to identify disease-causing genes, has turned into one of the most exciting adventures of humankind that aims to plumb the depths of who and what we are as biological beings.
Source: CME : Your SA Journal of CPD 23, pp 14 –17 (2005)More Less
Since all cellular development and function is controlled by our genetic make-up, it follows that our genome (all our DNA) has a fundamental influence on almost all human disease. <br>The Human Genome Project (HGP) aimed to produce the complete sequence of all the bases in all of human DNA, knowledge which should prove invaluable to the understanding of the pathogenesis and treatment of disease. <br>However, its output must be placed in context of current and future clinical practice. <br>Many recent genetic advances have come in spite of, or preceded, the publication of the human genome sequence in 2001. <br>The exact aetiology of some common genetic disorders has remained frustratingly elusive, despite knowledge of the full sequence of all human DNA. <br>Merely demonstrating an alteration of the sequence produced by the HGP is insufficient to explain human disease; complex genetic, protein and environmental interactions need to be elucidated to fully grasp the genetic underpinnings of disease. <br>By elucidating the basic genetic aetiology of disorders, targeted therapies may be designed, based on precise knowledge of abnormal physiology. <br>The HGP will have an ever-increasing impact on the understanding of common multifactorial disorders, in the rapid detection of disease-causing mutations and in determination of individual drug therapy.
Author Jacquie GreenbergSource: CME : Your SA Journal of CPD 23, pp 18 –21 (2005)More Less
Genetic testing using DNA is quick, cheap and easy. <br>Clinical assessment of the affected individual, and documentation of the pedigree (family history), should be the starting point for all diagnostic genetic testing as this will define which gene/s the laboratory should study. <br>Owing to the complexity of this type of testing, laboratories might have to screen many genes for mutations, or might only test a small number of known common mutations rather than offer a single test for each disorder. <br>It is therefore important to be aware that different laboratories use different methods and do different tests. Often different laboratories have to be used for different tests. <br>The National Health Laboratory Service (NHLS) is a good starting point for referrals, although they do not test for every genetic condition, but would have a good national and international referral network. <br>Genetic testing is by no means ready for prime time yet, so it is suggested that only testing known to have clinical benefit should be offered to the general public right now.
Author Bongani M. MayosiSource: CME : Your SA Journal of CPD 23, pp 22 –25 (2005)More Less
A complete and detailed family history is the cornerstone to the management of patients with cardiomyopathy. <br>Idiopathic DCM is a diagnosis of exclusion that should only be made after exhaustive non-invasive and invasive investigation to rule out potentially reversible causes of heart failure. <br>Clinical screening should be offered to all first-degree relatives (i.e. parents, siblings and children) of cases of HCM and idiopathic DCM. <br>A much lower diagnostic threshold is appropriate when interpreting diagnostic tests in first-degree relatives of patients affected with HCM and familial DCM. In particular, there should be careful examination of the ECG and the echocardiogram for subtle abnormalities in these cases. <br>A molecular genetic diagnosis can be useful in HCM in settings in which the clinical diagnosis is equivocal (e.g. borderline hypertrophy) or impossible (e.g. in the presence of hypertension) in association with a high incidence of sudden death, but this remains technically demanding. <br>Molecular genetic diagnosis in isolated individuals is generally not practical. <br>Laboratories that offer molecular genetic testing are limited to research institutions with an interest in inherited cardiovascular disorders. (Information about South African laboratories is supplied in the text.)
Source: CME : Your SA Journal of CPD 23, pp 26 –28 (2005)More Less
The LQTS syndrome, a genetic disorder characterised by cardiac arrhythmias which may be lethal, has been epidemiologically linked to cot death. <br>Previously it was classified as a disorder with only two forms, autosomal dominant and autosomal recessive, by a possible family history and the association with deafness. <br>It has now been mapped to at least 7 chromosomal loci (LQT 1-7); of these, 6 genes are known, of which all but one (LQT 3) are genes for transmembrane myocardial potassium channels. <br>The commoner forms (LQT 1-3) can be differentiated from one another by specific genotype-phenotype correlations, based on triggers for cardiac events. <br>Genetic studies of infants have confirmed molecular (DNA) links to the LQTS, and have defined effective drug treatment based on genotype. <br>Genetic testing now can establish the diagnosis, test individuals at familial risk and assist with accurate drug or other therapeutic options.
Author M.T. (George) RebelloSource: CME : Your SA Journal of CPD 23, pp 30 –31 (2005)More Less