- For the first time, geneticists have identified 45 new genes that cause blindness or cognitive disorders.
- They focused on a specific gene named SLC6A6.
- They were able to halt this deficiency in a little girl who was suffering from the same gene-related disorder.
The human genome contains 20,000 genes, and all of them could trigger certain types of diseases. Scientists estimate that nearly 7,000 unknown genes are responsible for recessive genetic disorders that arise from mutations in the two copies of the same gene inherited from each parent.
Recently, geneticists at the University of Geneva in Switzerland discovered 45 new genes responsible for blindness or cognitive disorders. They focused on a specific gene named SLC6A6. It encodes a multi-pass membrane protein that transports beta-alanine and an amino acid called Taurine.
Taurine is necessary for the functioning of the brain, retina, and heart. In pathogenic mutations of the SLC6A6 gene, individuals are more likely to suffer from a taurine deficiency, gradual loss of sight in both eyes (until they go blind), and develop a weak heart.
Geneticists found that this deficiency (visual degeneration and cardiomyopathy) could be compensated by using a taurine supplement.
Analyzing Genome Of 500 Pakistani Families
In this study, researchers analyzed the genomes of 500 Pakistani families who had both healthy and ill children. They chose Pakistani families because nearly 50% of marriages in the country take place between first cousins, which significantly escalates the risk of developing a recessive genetic disorder.
They focused on this particular family where two parents (healthy first cousins) had two healthy and two sick children: a 4-year-old girl was gradually losing her sight while a 15-year old boy lost all his sight. The girl was still able to differentiate between colors and shapes.
Researchers examined the blood of all family members and found that their illness was indeed associated with the SLC6A6 gene mutation. The gene creates a cell membrane protein that transports taurine, which plays a crucial role in the functioning of the retina and cardiac muscle.
The family’s genetic abnormality decreased the taurine’s carrying capacity to 15% of its normal level. It is a dietary supplement found in some energy drinks.
Researchers hypothesized that the progression of such diseases could be blocked by controlling taurine levels in children. They brought the suffering family to Geneva and diagnosed damage done to the vision and cardiac muscle in sick children. The boy had lost all his vision but fortunately, the little girl had some vision left.
After taking permission from the Swiss Ethics Commission, researchers gave 100 mg/kg of taurine food supplements every day to the children. To continue this process for a long duration, they organized regular cardiac and ophthalmologic monitoring sessions in Pakistan.
Anatomical stability with photoreceptor preservation | Credit: UNIGE
Within 3 days, the taurine levels in both children’s blood reached normal thresholds, increasing from 6 to 85 μ mol/l.
After 2 years, the little girl’s sight stopped degenerating. In fact, her eye got slightly improved: she could move around by herself. Sadly, the body didn’t saw improvement because he had already lost his whole retina. The cardiomyopathy, however, fully disappeared in both children.
The outcomes are really impressive. This is the first time scientists have been able to treat the heart and the retina by giving food supplements orally.
There are approximately 6,000 children in the world suffering from the same gene-related disorder. The team plans to identify new-borns affected by this condition so that they can be treated at an early stage. They will also continue to search for new genes that cause recessive disorders.