The Neurobiology of Mental Retardation: Fragile X Syndrome Essay

The Neurobiology of Mental Retardation: Fragile X Syndrome In my previous paper, I wrote on the topic of the nature-nurture debate and the ways it related to the brain-equals-behavior dilemma. In this paper, I will continue this investigation into the link between genes and neurobiology, but I will focus in on a particular aspect of the relationship: neurological disease caused by genetic aberration. There are many well studied and well documented (thought not necessarily well understood) disorders associated with the X chromosome, and a large number of these have neurobiological roots and behavioral manifestations. One such disease is fragile X syndrome. Fragile X syndrome is the most common inherited form of learning disabilities and mental retardation known (1). The disease shows an x-linked inheritance pattern and is characterized by a host of symptoms ranging from impaired learning abilities to severe retardation and autistic behaviors (1). An understanding of the disease is vital on several levels. Fragile X syndrome (FXS) not only bea rs scientific significance for the fields of molecular genetics, transmission genetics, neurophysiology, and abnormal psychology. It also provides one with a vantage point from which to view the particular set of behaviors known as mental retardation as well as those afflicted by retardation who are too often stigmatized and marginalized in our society. Before analyzing the neurobiological basis of FXS, it is pertinent to examine the genetics underlying the disease. As stated before, FXS is known to be x-linked which means that the disease will appear roughly in twice as many male cases as female. This is because males, who have only a single copy of x-linked genes which they inherit on... ... syndrome and Downs Syndrome are also forms of mental retardation, the latter of which is not even an inborn error of metabolism- it is a chromosomal disorder. And yet the particular subset of behaviors in question is all called mental retardation. Thus, more cytological and neuro-imaging research must be conducted to fully elucidate the complexities of FXS. For the time being, I think, it is safe to assume that the link between a single gene and a complex class of behaviors is strong for fragile X syndrome. WWW Sources 1)National Fragil X Foundation http://www.fragilex.org/ 2)Neurosciences on the Internet http://www.neuroguide.com/cgi-bin/pdistoc.pl?file=fragile 3)Genetic Causes of Mental Retardation http://specialed.freeyellow.com/YAdaptUse.html 4)Online Mendelian Inheritance in Man http://www3.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=309550