A study by researchers at Weill Cornell Medicine-Qatar (WCM-Q) has revealed the genetic cause of a neurological disorder and the implications it has for marriage.
The research examined the genetics behind cerebellar ataxia, a congenital malformation of the brain whereby the total volume of the cerebellum is diminished. This can result in the sufferer having problems walking, poor co-ordination and a tendency to be a ‘late developer’ as a child.
However, because cerebellar ataxia is often an inherited disease, it could have major implications for the consanguineous marriages that are common in Qatar, WCM-Q said in a statement yesterday. When the mutated gene that causes the disorder is expressed in a recessive manner, both parents have to have the same recessive gene for some of their children to be affected.
Since genes are inherited, it is much more likely that people within an extended family carry the same genes. Therefore, a consanguineous marriage within a family who carry the mutated recessive gene is much more likely to lead to cerebellar ataxia in the children of that marriage.
Investigators from WCM-Q, WCM in New York and Hamad Medical Corporation have now discovered an unusual recessive mutation that leads to cerebellar ataxia.Their results were recently published in the ‘Annals of Neurology.’
The study was carried out by Dr Alice Abdel Aleem (WCM-Q’s assistant research professor of neuroscience), along with Dr Elizabeth Ross (the Nathan E Cumming professor of neurology and neuroscience, and chair of the Neuroscience Graduate Programme at WCM in New York); Dr Mahmoud Fawzy Elsaid (senior consultant paediatric neurologist from Hamad General Hospital) and Dr Tawfeg Ben-Omran (senior consultant at Hamad General Hospital).
Dr Abdel Aleem said that the study was launched after a young woman visited her clinician with symptoms of cerebellar ataxia. Her brother was also found to have the disorder and the researchers asked if they, and their extended family, would take part in research to examine the genetic cause.
Blood samples were taken from two branches of the family and DNA, RNA and protein were extracted. The data was then analysed by the study research team and the WCM-Q Bioinformatics Core. After looking at the entire genome, a rare variation in the DNA sequence of non-protein coding ribonucleic acid called RNU12 was found. This RNU12 variant was associated with affected family members, following the inheritance pattern expected of a recessive gene.
Laboratory investigations confirmed that the variant impacts the expression and function of RNU12. This is an exciting finding, since most disease-associated mutations identified to date involve the small fraction of the genome that encodes proteins.
Dr Abdel Aleem said the study will open a new window for screening for cerebellar ataxia.
“It also shows geneticists how important it is to conduct research on all parts of the genome – both protein-coding and non-coding – when looking for causes of disease."
The research team that conducted the study.