Hydrocephalus

Hydrocephalus
Hydrocephalus is an anomaly which origins have been linked to both genetic and environmental factors. Saladin, (2007) has defined hydrocephalus as an abnormal accumulation of central spinal fluid (CSF) in the brain usually as a result of a blockage in the CSF flow and the subsequent reabsorption. The rate of occurrence of hydrocephalus varies by whom is asked; there are not any national registries therefore there is not a data base that can accurately depict a real number of people afflicted with this anomaly. Instances of hydrocephalus are not all associated with genetics, some other factors that have been documented are: congenital malformations, intercerebral hemorrhage, infection and maternal alcohol abuse. Two article will be discussed in the paper; one article is dedicated to genetics while the second article discusses environmental factors that have been associated with hydrocephalus.
Article 1 Genetics of human hydrocephalus
The article discusses that evidence is mounting that genetic factors play a role in the “pathogenesis of hydrocephalus”. Hydrocephalus has two forms; acquired and inherited. There are several documented instanced of genetic involved in hydrocephalus in animals, but the documentation that has been gathered to date is not as substantial in human hydrocephalus. “Hydrocephalus is considered complex and has multifactorial neurological defects.” It is believed that one of the possible causes is related to protein and signal disruption during the early development of the fetal brain. The article covers the documentation obtained on animals and believes that this is an initial phase in human research, but at this time human research has not developed into a significant number of studies. To better understand hydrocephalus and to develop better research tools, a large and diverse research study group will have to be assembled. This may allow for a better opportunity to determine if there are more of hydrocephalus exist. If more forms are identified then the genes associated with each form can be isolated and the characteristics and functions of the identified genes can be studied and thus can result in better patient care. John Hopkins Institute has been approved to begin a study on hydrocephalus. The authors of this article discussed that there is a possibility the not all of the instanced of hydrocephalus are related to the flow and absorption of CSF, because the article suggests that this is identified by the fact that an effective shunt placement does not always prevent progressive deterioration of the disease. The study will have an objective to determine the gene which is responsible for hydrocephalus and the functions of the associated genes. The hope of the research will be multifold; to determine the causes of hydrocephalus and more effective treatment (Zhang, Williams, Rigamonti, 2006).
Article 2 Hydrocephalus following prenatal exposure to ethanol
This article is based on research on pregnant laboratory mice that were introduced to various quantities and frequencies to ethanol alcohol. The author defines fetal alcohol syndrome (FAS) as “a disorder that can occur to the embryo when a pregnant woman ingests alcohol during pregnancy”. The article discusses that there has been studies that link FAS to the disruption of the L1 protein and thus a subsequent disruption to the neural formation of the proteins in the cells and thus an increase the likelihood of hydrocephalus. The article has a table that demonstrates as the amount of alcohol increased in the laboratory mice so did both the frequency and severity of hydrocephalus with exception of the mice that received the greatest alcohol. The study did show enlarged ventricles and separated septum throughout all specimens that were introduced the alcohol. There has been documented instances of FAS children having hydrocephalus, but as mentioned in the previous article, the frequency of this occurrence in unknown because of the lack of a database. The article does provide a disclaimer that the incident of human hydrocephalus secondary to prenatal alcohol exposure is unknown. The research finally showed that the majority of the test mice had enlarged ventricles but only a few demonstrated obstructions. It is also suspected that other factors also have a role in the increased incident of hydrocephalus secondary to exposure of prenatal alcohol.
Genetics vs Environmental Hydrocephalus can be classified in both categories as there are instances that it is linked to both genetics and environmental factors. “It is estimated that about 40% of hydrocephalus cases have a possible genetic etiology”. There has been only one instance of the hydrocephalus X gene identified in humans (Haverkamp, Wolfle, Aretz, 1999). In most instances of hydrocephalus it is believed to be associated with environmental factors such as trauma and infections. However, congenital hydrocephalus seems most often as classified as a genetic disorder. The traits associated with the genetics are recessive. Hydrocephalus has a XLD inheritance pattern meaning that it is single gene mutation of the X chromosome and just one copy of the mutant will be present.

References
Haverkamp F, Wolfle J, Aretz M, et al. (1999) Congenital hydrocephalus internus and aqueduct stenosis: aetiology and implications for genetic counselling. Eur J Pediatr 158:474–478.
Sakata-Haga, H., Sawada, K., Ohnishi, T., & Fukui, Y. (2004). Hydrocephalus following prenatal exposure to ethanol. Acta Neuropathologica, 108(5), 393-8. doi: http://dx.doi.org/10.1007/s00401-004-0901-8 Zhang, J., Williams, M., Rigamonti, D. (2006). Genetics of human hydrocephalus. Journal of Neurology, 253(10), 1255-66. doi: http://dx.doi.org/10.1007/s00415-006-0245-5