It is possible to understand the importance of genetics in
the development of diseases by considering estimates that indicate
that in Europe 30 million people are diagnosed with a hereditary
disease.
With the completion of the Human Genome Project, which allowed
the complete codification of our DNA, today we are finally able to
diagnose a greater number of genetically transmitted diseases:
"We can
consider our DNA like an enormous book containing an impressive number of
letters that shape the words of computed meaning which are our genes",
explains Prof. Marco Seri, Director of the Operating Unit of Medical
Genetics at Sant'Orsola-Malpighi Polyclinic: "it is now possible to read
all these words and see if a letter has changed, indicating the appearance
of a word without sense, which means if we are facing the mutation of a
gene that determines the presence of a non-functional protein and,
consequently, of a genetic disease. DNA also has variables that do not
determine, in a direct manner, the presence of a disease, but that can, in
conjunction with environmental factors, predispose a person to a disease."
As far as eye diseases are concerned, we know that a good number of
them are transmitted genetically and can cause important disabilities:
"among the genetic eyes diseases which can be transmitted to members of a
family, we find some forms of corneal dystrophy, glaucoma, cataracts,
retinal degeneration among which retinitis pigmentosa.
"Heterogeneous
genetics", in other words the fact that the same disease can be caused by
mutations in various genes, also exists. If we take, for example,
retinitis pigmentosa, we know that more than 100 genes have been described
and are responsible for the eye affections. Often, from a clinical point
of view, patients cannot be distinguished between one another, but from
the genetics point of view, their forms are different sometimes even with
a different modality of transmission."
Why would genetics counselling be important?
"There can
be immediate effects on the individual as well as the family: it is
possible to stabilize, for example, who are the healthy carriers of a
disease and the risk to have a sick child if two healthy carriers of the
same defect end up together."
What are future perspectives for genetic
therapy?
"To know of an altered gene and consequently the protein that
does not work could help understanding the mechanisms that cause the
disease itself, that is its pathogenesis, and putting in place new
therapeutic strategies, pharmacological or not.
Conceptually, genetic
therapy would be a simple procedure based on modifying the altered gene in
the cell affected by the disease.
In reality, it is a very complex process which application
still today has remained isolated to a few cases."
At the present
time, in Italy, experimentations are being conducted on a specific ocular
pathology: "It is an experimentation for genetic therapy in patients with
Leber's congenital amaurosis and a mutation of the gene RPE65, and it is
lead by a team at the University of Naples and by the TIGEM lab in Naples
as well. Data are very promising and we hope that in the future new
experimentations will be carried out for other eye diseases."