Friday, January 15, 2010
Case Study: Spinocerebellar Ataxia in a Turkish Family
The following study was performed on a Turkish family with a history of SCA type 2.
The first patient (II.2) is a 49 year old female. During her 40s, she began to experience symptoms of SCA. Initial signs included disequilibrium (loss of balance) and dysarthria (difficulty in speech). Her condition continued to worsen and within two years, she was having trouble controlling her hand movements. Testing showed abnormalities in her eye/ limb movements and gait and an MRI scan confirmed that these symptoms were caused by cerebellar atrophy, or the shrinking of the cerebellum. However, her cognitive senses appeared to be fine after she received a score of 29/30 on her minimental status test (a test used to detect for any cognitive impairment).
Her brother (II.3), who was 47 years of age at that time, also began experiencing disequilibrium in his 40s.
Their mother (1.4) has similar symptoms, but the onset of the disease did not appear until she was in her 60s. She also has a case of explosive speech, which is loud and sudden talking that cannot be controlled.
The son of the first patient (111.1) began to experience symptoms when he was only in his 20s. At first, he had head titubations. This later progressed to more severe symptoms, similar to the ones that his mother had experienced: dysarthria, eye and limb movement impairments. MRI testing revealed that he also had cerebellar atrophy.
Fig. 9 - Pedigree which shows the family history of the four patients mentioned above
Source: http://www.marmaramedicaljournal.org/pdf/pdf_MMJ_399.pdf
Fig. 9 shows the inheritance of SCA in this family. We can see that the disease is autosomal dominant because of three good indicators:
a) the disease appears in each generation
b) the disease seems to affects males and females equally
c) the disease affects approximately half of the children
This case study is a good example of anticipation, which was explained in an earlier post. In this family, the onset of the disease did not appear in the parent generation until she was in her 60s. However, the F1 generation experienced symptoms when they were in their 40s, and in the F2 generation had developed symptoms by the time he was only in his 20s. From this, we can conclude that there is a general trend: with each new generation, the disease appears at an earlier age than in the previous generation.
