Spinocerebellar Ataxia Essay
Inheritance and Symptoms
Spinocerebellar ataxia is divided into two primary categories: acquired and heredity. Acquired (non-genetic) ataxia is caused by trauma or environmental damage to the cerebellum. Several physical causes of are stroke, tumors, or head injuries like concussions. Chemical causes that can lead to SCA are: lead exposure, excessive alcohol levels, HIV, Chickenpox and even vitamin B12/ E deficiency. There are two sub categories of heritable spinocerebellar ataxia divided according to heredity. First there is the autosomal dominant spinocerebellar ataxias (SCA). SCA heredity follows mendelian inheritance in a dominant pattern with a 50% chance of an afflicted offspring, a list of autosomal dominant SCA is listed in Table 1. Secondly there is autosomal recessive ataxias (SCAR), …show more content…
heredity follow mendelian genetics and assuming both parents are carriers then 25% of offspring will be afflicted and a list of such diseases are in Table 2. In one reported case of spinocerebellar ataxia, the genetic link had been identified as being X-linked (SCAX1).
Spinocerebellar ataxia is a broad category of neurodegenerative genetic diseases that result in a progressive loss of motor function via degeneration of the cerebellum.
Thus, most symptoms associated with SCA and SCAR are related to the damage of the cerebellum. Common symptoms of SCA are unsteady way of walking (gait) that may be accompanied by awkward eye-hand coordination and slow, weak, or imprecise speech.6 Since there are a number of different heritable spinocerebellar ataxias clinical symptoms and prognosis of the disease can be difficult to determine and vary considerably between each form. Each form of SCA and SCAR can be considered its own disease and without genetic testing a proper diagnosis can be difficult. Age of onset varies depending on form of the SCA and the “Impact” of the defective gene to the afflicted individual. The term “Impact” is used to describe the version of the mutated gene that causes the SCA- phenotype. For example, SCA1 can have an onset age of 40 years of age or 20 years of age. This variation is due to the number of trinucleotide repeat mutations that cause the disease. The more repeats present the earlier the age of onset of
symptoms.
Dominant spinocerebellar ataxias are present in both females and males at the same rate. The estimated population of individuals with SCA in the United states at any time is 150,000. Some SCAs have a higher penetrance in specific ethnic groups around the world. There have been a number of founding populations to specific SCAs. Table 4 is a short list displaying the seven most common dominant ataxias that are prevalent in specific populations. SCAs have a prevalence of around 1 to 5 cases per 100,000 people. 7-8 SCA type 3 is the most common form of the disease worldwide; types 1, 2, 6, 7 and 8 have greatly varying prevalence depending on the ethnic background of the population. 9,10 There is a large SCA12 population in Portugal and the once Portuguese colony of brazil.
Spinocerebellar ataxia is divided into two primary categories: acquired and heredity. Acquired (non-genetic) ataxia is caused by trauma or environmental damage to the cerebellum. Several physical causes of are stroke, tumors, or head injuries like concussions. Chemical causes that can lead to SCA are: lead exposure, excessive alcohol levels, HIV, Chickenpox and even vitamin B12/ E deficiency. There are two sub categories of heritable spinocerebellar ataxia divided according to heredity. First there is the autosomal dominant spinocerebellar ataxias (SCA). SCA heredity follows mendelian inheritance in a dominant pattern with a 50% chance of an afflicted offspring, a list of autosomal dominant SCA is listed in Table 1. Secondly there is autosomal recessive ataxias (SCAR), …show more content…
heredity follow mendelian genetics and assuming both parents are carriers then 25% of offspring will be afflicted and a list of such diseases are in Table 2. In one reported case of spinocerebellar ataxia, the genetic link had been identified as being X-linked (SCAX1).
Spinocerebellar ataxia is a broad category of neurodegenerative genetic diseases that result in a progressive loss of motor function via degeneration of the cerebellum.
Thus, most symptoms associated with SCA and SCAR are related to the damage of the cerebellum. Common symptoms of SCA are unsteady way of walking (gait) that may be accompanied by awkward eye-hand coordination and slow, weak, or imprecise speech.6 Since there are a number of different heritable spinocerebellar ataxias clinical symptoms and prognosis of the disease can be difficult to determine and vary considerably between each form. Each form of SCA and SCAR can be considered its own disease and without genetic testing a proper diagnosis can be difficult. Age of onset varies depending on form of the SCA and the “Impact” of the defective gene to the afflicted individual. The term “Impact” is used to describe the version of the mutated gene that causes the SCA- phenotype. For example, SCA1 can have an onset age of 40 years of age or 20 years of age. This variation is due to the number of trinucleotide repeat mutations that cause the disease. The more repeats present the earlier the age of onset of
symptoms.
Dominant spinocerebellar ataxias are present in both females and males at the same rate. The estimated population of individuals with SCA in the United states at any time is 150,000. Some SCAs have a higher penetrance in specific ethnic groups around the world. There have been a number of founding populations to specific SCAs. Table 4 is a short list displaying the seven most common dominant ataxias that are prevalent in specific populations. SCAs have a prevalence of around 1 to 5 cases per 100,000 people. 7-8 SCA type 3 is the most common form of the disease worldwide; types 1, 2, 6, 7 and 8 have greatly varying prevalence depending on the ethnic background of the population. 9,10 There is a large SCA12 population in Portugal and the once Portuguese colony of brazil.