Information on the Causes of Congenital Disorders
Someone dear to me was born with a number of physical (not mental) birth defects known together as VACTERL Association. This person spent a great deal of time in the hospital as a baby, and had a number of surgeries at a young age. Now this person is perfectly healthy, but this person is still, albeit to a relatively small degree, visibly “different.” Ever since I was quite young, I have struggled with the reason why. It has always seemed frustratingly unjust to me that most people are born with “regular” bodies, while some, seemingly randomly, are not. Here, I will explore the causes of disorders like VACTERL, and also look into the differences, if any, between “genetic” and “developmental” birth defects.
VACTERL Association is a group of physical defects, not unrelated, that are found together in infants. VACTERL is an acronym for the various anomalies – V for vertebral anomalies, A for anal atresia (in some cases there no anal opening), C for cardiovascular problems, T for tracheoesophagal fistula (in some cases the trachea and the esophagus are not properly connected), E for esophageal atresia (in some cases part of the esophagus is missing), R for renal, or kidney, anomalies, and L for limb (especially hands, legs, and feet) anomalies. An infant with three or more of these, all of which may vary in severity, is diagnosed as having VACTERL Association. Therefore, each child with VACTERL Association is unique in the number of anomalies he or she has and in the varying degree of severity of each.
From what I have been told from a young age about VACTERL, I gathered that it was “not genetic,” and was “developmental.” After some research, I realize that I have been using these terms incorrectly. I realize that when I said that VACTERL was “not genetic,” I meant that it was not inherited. I say that it is not inherited because VACTERL does not seem to occur multiple times in one family; as far as we know, it is “random.” When I said that it was “developmental,” I meant that the problems arose during development in the womb. Now I understand that birth defects that are caused by genetic mutation are not always inherited. I also understand that what I was calling a “developmental” defect is actually known as a congenital disorder or congenital anomaly.
Congenital disorders or anomalies are caused by problems that arise during the development of the fetus. Many of these problems are in fact caused by genetic factors; they are either inherited or caused by unprompted mutations. Some of these problems, however, are not caused by genetic factors, but are caused by the environment during pregnancy (i.e. fetal alcohol syndrome). These problems during development cause one to be born with defects, or anomalies. The severity of the congenital anomaly(ies) depends on the stage of development at which the problems arise. The earlier in the pregnancy that problems occur, the more severe the anomaly(ies), and vice versa. A congenital anomaly may vary in severity, from something so minor that it does not affect the person’s health or is even very noticeable, to anomalies that have a more major impact on the person’s health or are quite noticeable.
VACTERL Association is clearly a set of related congenital anomalies. However, the cause is unknown. It is called an “association” rather than a syndrome because a gene has not yet been identified as causing VACTERL. It is clearly not inherited, as it does not seem to occur more that once in families, however, the cause may still be found in genetics in the form of some kind of unprompted genetic mutation. It seems that diabetic mothers are more likely to have a child with VACTERL, however, mothers that are not diabetic may also have children with VACTERL. It is quite rare, happening in about 16 out of 100,000 live births. Although the specific cause of VACTERL has not yet been found, we can look to similar disorders to see what the answer might be.
Klippel-Feil syndrome is a congenital disorder that involves the fusion of 2 cervical vertebrae, as well as an assortment of associated anomalies that may or may not also be present, such as scoliosis, spina bifida, rib anomalies, kidney anomalies, cleft palate, heart problems, respiratory problems, facial anomalies, genital anomalies, skeletal anomalies, and muscle anomalies. Like VACTERL, it is a rare, physical disorder. Unlike VACTERL, however, there have been reports of it occurring multiple times in a family, in addition to “sporadic” cases. Some genes have been identified as potentially being the cause of the syndrome (for more information on specific genes, see websites below). Although Klippel-Feil syndrome is different from VACTERL Association in that in some cases it does appear to be inherited, I think that the fact that there are sporadic cases (like VACTERL), and that some genes were still able to be identified as potentially causing the syndrome, may indicate that the cause of VACTERL could also be found in genetics.
When I set out, I wanted to learn more about “birth defects,” and the difference between what I called genetic and developmental causation. What I have found is that these categories are quite often blurred. Congenital anomalies are often caused by some genetic factor, be it inherited or not, and this genetic factor often effects the development of the fetus. I then decided to take a closer look at the causes of congenital disorders and anomalies to gain a greater insight into the causes of VACTERL, something that is important to me personally. Although the specific cause of VACTERL is unknown, through my research I was able to gain a greater understanding of the general causes of congenital anomalies and am able to more readily speculate about the causes of VACTERL.
I hope that the study of the causes of congenital disorders will eventually lead to the discovery of better treatment for these disorders, and perhaps even ways these disorders can be prevented. Disorders like VACTERL, which are composed of a number of anomalies, have an enormous affect the lives of those born with them. Surgeries are traumatic experiences for babies and young children, despite doctors’ best efforts (not to say that surgeries aren’t important, they save lives. I'm just saying that it is a tough thing to have to go through, especially at a young age). Not to mention, being visibly “different,” even if one is completely healthy and fully functional, is extremely difficult for people, especially as they grow up. Though I now have a greater understanding of the causes of congenital anomalies, it still seems upsettingly unfair to me.
Something that I find surprising is that things like this don’t happen more often than they do. With so many things that could go wrong during the development of our bodies, it amazes me most of us seem to turn out with few problems. This is true of life in general as well; it is astounding that things go "right" as often as they do when considering the number of things that could go "wrong" or, rather, "different."
- National Organization for Rare Disorders: http://www.rarediseases.org/
- Stanford Health Library (information on genetics and birth defects): http://healthlibrary.stanford.edu/resources/bodysystems/genetic_mca_sw.html#MCA-V
- The VACTERL Network: http://www.vacterlnetwork.org/default.asp
- More information: http://www.thefetus.net/page.php?id=446
- More Information: http://www.cincinnatichildrens.org/health/heart-encyclopedia/disease/syndrome/vacterl.htm
- Some information on VACTERL and genetics: http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=192350
- Information on syndrome and genetics: http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=118100
- Information on syndrome: http://www.madisonsfoundation.org/index.php/component/option,com_mpower/Itemid,49/diseaseID,455/
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