It is usually easier to argue for biology than for other sciences that studying it as children will be useful to us later in life. It is a more obvious and less abstract connection with Nature and living beings. Still, when I started graduate school in "molecular biology" it became abstract, and trying to explain what exactly I spent more than 5 years of my life studying and working on in one single laboratory was tricky at times. Nowadays though, we read about "genes", "DNA" and "mutations" in newspapers and websites written for lay audiences. The important applications in some fields, especially medicine, that molecular biology and genetics offer are now more widely appreciated.
We all know that there is genetics in our lives, even intuitively when we see resemblances with our parents and grandparents, mostly physical in nature but also in character and personality sometimes. We have also been aware for centuries that if there is a disease in our family tree, chances are we will get it too. In simple terms, there is a "defective" gene running in the family which is being inherited with a certain probability. In fact, the "defect" is an alteration of the "normal" copy of the gene - a mutation or group of mutations in a gene that encodes a protein product with a specific role (for more information on these topics see “genetics and mutations” on my homepage, and the blog entry on PCR and its applications). These mutations result in an abnormal form (or absence, or decreased amount) of the protein product that this gene encodes, which, in the right context (the cells or tissue where this protein is relevant or "expressed") can lead to diseases such as cancer. What molecular biology has provided us with are tools, which become more efficient every year, to determine which specific mutations are linked to certain diseases. Once this is determined, the test becomes generally available (although this may be restricted to those who can afford it when insurance does not cover it) to people at risk. This risk, once again, is usually defined based on family history. Below is a table showing some diseases for which the mutations in the gene(s) affected are well or partially known.
We all know that there is genetics in our lives, even intuitively when we see resemblances with our parents and grandparents, mostly physical in nature but also in character and personality sometimes. We have also been aware for centuries that if there is a disease in our family tree, chances are we will get it too. In simple terms, there is a "defective" gene running in the family which is being inherited with a certain probability. In fact, the "defect" is an alteration of the "normal" copy of the gene - a mutation or group of mutations in a gene that encodes a protein product with a specific role (for more information on these topics see “genetics and mutations” on my homepage, and the blog entry on PCR and its applications). These mutations result in an abnormal form (or absence, or decreased amount) of the protein product that this gene encodes, which, in the right context (the cells or tissue where this protein is relevant or "expressed") can lead to diseases such as cancer. What molecular biology has provided us with are tools, which become more efficient every year, to determine which specific mutations are linked to certain diseases. Once this is determined, the test becomes generally available (although this may be restricted to those who can afford it when insurance does not cover it) to people at risk. This risk, once again, is usually defined based on family history. Below is a table showing some diseases for which the mutations in the gene(s) affected are well or partially known.
There is a genetic risk associated with certain diseases. For diseases like cancer, additional elements such as environmental factors, stress, smoking and life style also influence the risk of developing disease. Long-term research conducted on patients (and sometimes their families) suffering specific diseases has led to genetic testing being now available for people either suffering symptoms or at potential risk of developing symptoms later in life, as well as those who may be just “carriers” for the (in this case, recessive) mutations conferring the risk and who can transmit the risk to their progeny by passing the “defective” gene on. These tests are performed on a sample from the patient (usually blood) and use PCR-based DNA sequencing or related techniques to detect a specific gene that is known to be associated with the disease. The results will indicate whether the patient’s gene contains mutations that are associated with the disease, and genetic counseling may be recommended to discuss exact risk. In some cases, when the patient presents symptoms, genetic testing is done to confirm the diagnosis. For "dominant" mutations such as the ones that result in Huntington's disease (a severe neurodegenerative illness that becomes apparent most often in mid-life) inheriting one copy of the mutated gene is enough to predict an almost 100% of developing Huntington's at some point in life.
For people who suspect genetic risk in their families, they may want to be tested with their partners before trying to get pregnant. There is also a risk associated with certain ethnic backgrounds. For example, as I am about 75% Ashkenazi Jew, I got tested for a panel of possible mutations which are associated with pretty severe disorders that usually result in progressive degeneration and early death. Most of these mutations are of very high frequency in this population (about 1:100 in some cases or higher) compared to almost absent in other backgrounds. Both parents must be carriers of the “defective” (or mutated) gene for the disease for a child to get it though, so a positive test for an adult means only that he/she is a carrier. If both parents are carriers, there is a 25% chance of having a sick child (who would inherit one defective gene from each parent). This child also has a 50% chance of being a carrier (inheriting one defective copy from either parent) and a 25% chance of not inheriting any of the mutated genes, as shown in the top panel of the figure below. Another scenario (lower figure) shows the risk of passing a carrier gene to your child when only one of the parents is a carrier (50%).
For people who suspect genetic risk in their families, they may want to be tested with their partners before trying to get pregnant. There is also a risk associated with certain ethnic backgrounds. For example, as I am about 75% Ashkenazi Jew, I got tested for a panel of possible mutations which are associated with pretty severe disorders that usually result in progressive degeneration and early death. Most of these mutations are of very high frequency in this population (about 1:100 in some cases or higher) compared to almost absent in other backgrounds. Both parents must be carriers of the “defective” (or mutated) gene for the disease for a child to get it though, so a positive test for an adult means only that he/she is a carrier. If both parents are carriers, there is a 25% chance of having a sick child (who would inherit one defective gene from each parent). This child also has a 50% chance of being a carrier (inheriting one defective copy from either parent) and a 25% chance of not inheriting any of the mutated genes, as shown in the top panel of the figure below. Another scenario (lower figure) shows the risk of passing a carrier gene to your child when only one of the parents is a carrier (50%).
Different life ‘happenings’ can restrict the access to information we have from our ancestors- generations moving abroad because of war or persecution (and subsequently losing touch with older generations and relatives), being adopted, or having parents dying at a young age. When you are a female and you lose your mother early in life, as you grow older you wonder about female-specific life processes and how these were (or would have been) for her. Especially when going through events such as having your first period (menarche), getting pregnant and having children, and later on, menopause. These events can also be genetically determined to a certain extent in terms of (for example) how old we are when they happen and which ‘symptoms’ are associated with them. The risk of developing thyroid disease may also have a strong genetic component.
RSS Feed