Teratogen
Teratogens are described as mutagenic compounds that can be responsible for various congenital disabilities. The agents are either, in the environment that the mother may be exposed to during pregnancy or in drugs taken during the period. These compounds are usually identified during a prevalence of congenital disabilities within a particular populace. Different teratogens have varying effects depending on their dose and duration of exposure. The first half of the pregnancy comprises of the most vulnerable period. Therefore a variety of compounds exists that pose the threat of congenital disabilities for developing fetus although we focus mainly on an antiepileptic drug.
Common Teratogens
Compounds that affect fetal development are commonly found in homes and work places. As earlier mentioned, they include drugs, cleaning detergents, ionizing agents, and mercury and lead pipes. Furthermore, various teratogenicity compounds include conventional infectious agents such as rubella cytomegalovirus, herpes simplex, toxoplasma, and syphilis. Among the named compounds, antiepileptic drugs have been proved to be teratogenicity (Genetic Alliance, 2010). Thus, these chemicals are widely distributed in the environment.
Phenytoin
Phenytoin is one of the commonly used anti-epileptic drugs. The drug is a hydration derivative that has a minimal sedative effect. The drug is linked to the fetal hydration syndrome. Affected children are born with hypoplasia and irregular ossification of distal phalanges as the primary characteristic feature of the disorder (Hill et al., 2010). If the mother takes phenytoin during the first trimester, there is a 10% chance that the child will be born with the syndrome (CHW, 2017). Moreover, there is a 33% chance that they will also have a combination of growth deficiency, developmental delay, cleft palates, certain facial characteristics, heart defects, genitourinary abnormalities and malformed fingers and nails. Thus, the drug is proved to have adverse effects on the fetus.
Effects of Phenytoin
The drug can have adverse effects as a result of how it reaches the child. It can lead to dilation (Phenytoin), in a way that more dosage of the medication gets to the fetus than the mother (Battino & Tomson, 2007). This phenomenon is increasingly prevalent in the first trimester of pregnancy compared to other stages. Dilation is also metabolized slower in by the fetus and, thus, lasts longer in the child than the mother. However, a combination of other causes could also play a role in the development of the syndrome. The mother’s genetic influence towards metabolism of phenytoin may affect the overall action of the drug though it is still unclear. Women with mutations in the methylenetetrahydrofolate reductase (MTHFR) are at a higher risk of having a child with hydantoin syndrome (Battino & Tomson, 2007). Epileptic women should do a thorough consultation with a neurologist and an obstetrician before planning a pregnancy. This move will help control seizures without necessarily harming the child (Battino & Tomson, 2007). Therefore, the mode of action of the drug affects the child more than it does the mother.
Symptoms and Possible Intervention
There is no formal test for diagnosing the syndrome. Although, as earlier mentioned, the drug has many defining characteristics. Other symptoms include poor prenatal development resulting in small babies. Growth deficiency will vary depending on the intensity of the drug use. Aforementioned distinctive facial features may also be present; they include, a broad flat bridge of the nose, shortened eye lids, eyes that are more distantly located than usual, droopy eye lids, large wide mouths, and missing tissue on the roof of the mouth (NORD, 2015). Most of these facial features can be easily corrected by surgery. The cost varies with the intensity of the damage to the child, although some are irreversible, such as those that affect the eye and skull structure. Progressively in life, children have delays attaining developmental milestones, such as learning to sit up or crawl.
With time, the kids seem to improve, but studies indicate that they lag behind when compared to unexposed siblings. Intellectual disabilities are also visible in children (NORD, 2015). These kids will need special education where they are intensely affected. Therefore, the children exhibit a variety of symptoms some of which persist to later on in life.
Prevention
Prevention measures are available. The standard recommendation is that epileptic women should be treated with a single anticonvulsant prior and throughout pregnancy as multiple antiepileptic drugs seem to have a greater chance resulting in congenital disabilities (NORD, 2015). Where phenytoin is the administered drug, the women are recommended to take folic acid supplements both prior and during the pregnancy. The supplements reduce the risk of malformations.
Conclusion
A variety of compounds that can cause birth deformities are present in the immediate environment. These chemicals are known as teratogens. Drugs used to treat epilepsy are linked to several congenital disabilities. Phenytoin, in particular, causes hydantoin syndrome, which has a severe consequence on the prenatal development of the child and their intellectual development throughout life. Nonetheless, intervention techniques that either helps prevent or treat the symptoms of the syndrome are available.
References
- Battino D., & Tomson, T. (2007). Management of epilepsy during pregnancy. Title of Journal, 67(18), 2727-46. doi: https://www.ncbi.nlm.nih.gov/pubmed/18062721
- CHW (2017).Phenytoin (Dilantin). Retrieved from http://www.chw.org/medical-care/genetics-and-genomics-program/medical-genetics/teratogens/phenytoin-dilantin/
- Genetic Alliance (2010 Feb 17). Appendix A, Teratogens/Prenatal Substance Abuse. Available from: https://www.ncbi.nlm.nih.gov/books/NBK132176/
- Hill, D. S., Wlodarczyk, B. J., Palacios, A. M., & Finnell, R. H. (2010). Teratogenic effects of antiepileptic drugs. Expert Review of Neurotherapeutics, 10(6), 943–959. http://doi.org/10.1586/ern.10.57
- NORD (2015). Fetal Hydantoin Syndrome. Retrieved from https://rarediseases.org/rare-diseases/fetal-hydantoin-syndrome/
