London: In what could be called a major breakthrough, scientists claim to have identified a gene which is linked to birth defects in many individuals.
An international team, led by Leeds University, has, in fact, found the genetic cause of inherited conditions -- Meckel-Gruber syndrome and Joubert syndrome -- that causes
severe foetal abnormalities, the `Nature Genetics` reported. Meckel-Gruber syndrome and Joubert syndrome are part of a wider family of disorders known as "ciliopathies" --
so called because the cilia are not working as they should and don`t respond properly to signals.
This lack of communication can prevent the neural tube from developing correctly in growing embryos, leading to abnormalities in the brain. Affected embryos can also develop abnormalities in the eyes, extra fingers or toes, and multiple cysts in their kidneys, say the scientists.
To find the gene responsible for Meckel-Gruber and Joubert syndromes, the scientists examined DNA from families with a history of the disorder, from skin cells donated by
patients, and from cells grown in the laboratory. They also studied zebrafish, which have very visible embryos.
The work identified a previously unknown gene -- TMEM216 -- as a cause of Meckel-Gruber and Joubert syndromes.
They also showed that the faulty TMEM216 gene stopped cells from making a protein that is needed for signalling.
Because Meckel-Gruber and Joubert syndromes are recessive genetic disorders, only couples who both have a copy of the disease gene are at risk of conceiving babies with
these birth defects.
According to the scientists, the finding should allow couples at risk of conceiving babies with the profoundly disabling Meckel-Gruber and Joubert syndromes to be identified
beforehand through genetic screening.
"Accurate genetic testing for TMEM216 will be particularly important for families throughout the world that have a history of ciliopathies caused by mutations to gene.
"Now that we have identified a gene that causes Meckel-Gruber syndrome and Joubert syndrome, the role of particular signalling pathways whilst the embryo is developing
can also be more clearly understood," Prof Colin A Johnson, who led the team, said