Monday, 2 April 2012

Deafness Found Lurking in Genes


Recently I was at my grandfather’s 80th birthday party. My grandfather is so deaf that you often have to clearly shout in his general direction for him to make sense of words. His hearing aids, which he has worn for almost ten years now, need their batteries changed every 5 to 7 days. He is so deaf, in fact, that my mother bought him a special phone for the hearing impaired which quite literally only has the loudspeaker function. My grandfather’s loss of hearing has gradually deteriorated over the decades and it is something that he has become accustomed to. For sufferer’s of Postlingual nonsyndromic hearing loss however, the deterioration of hearing happens so quickly and so early on in life that they find it hard to adjust to their new lifestyles.

Postlingual nonsyndromic hearing loss is an uncommon impairment that lowers a person’s sound detection over time. The onset of this type of deafness occurs only in males during the ages of 5 and 15. Recently in the University of Miami Miller School of Medicine, teams of eager researchers have discovered a direct link between this form of premature deafness in boys and the PRPS1 gene located on the X chromosome. In their study, they examined a large Chinese family (a race where nonsyndromic deafness seems to be most prominent) who had multitudes of cases involving the hearing loss trait. Click here to view the full abstract of their experiment.

During the screening of their DNA, four different mutations were detected, resulting in a depleted amount of activity in a specific enzyme. By analyzing the structure of this enzyme, they recognised that it affected red blood cells and the connective tissue that produces collagen and other fibres. Due to the lack of this enzyme, the mutation in the gene was linked to the formation of different types of hairs found in the cochlea of the sufferers, and has therefore been elected as a good candidate for further genetic examinations regarding nonsyndromic hearing loss.

The current information that scientists have about Postlingual Nonsyndromic hearing loss can only constitute for basic treatments and coping mechanisms for patients as well as their relatives. However, throughout the course of this extensive study, newly discovered genetic links will give an insight into possible therapeutic treatments and preventative options for this type of deafness. This in turn will hopefully assist in the discovery or new treatments, and the detection of new methods of genetic manipulation for other forms of hearing loss also. This could include new coping mechanisms for cases like my grandfather’s, and for many of the elderly population who have needed to alter their lifestyles to cater for their impairments.


Hannah Culley - 42942810
References:

Gonzales, Robert T- 2011, 10 New Genetic Discoveries – And the Diseases they Could Treat, io9, viewed 18 March 2012 http://io9.com/5835215/10-recent-genetic-discoveries-and-the-diseases-they-will-help-treat

The American Society of Human Genetics All Rights Reserved 2010, ‘Loss-of-Function Mutations in the PRPS1 Gene Cause a Type of Nonsydromic X-Linked Sensorineural Deafness’, The American Journal of Human Genetics, vol. 86, no. 1, viewed 18 March 2012

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