Gene therapy

As you almost certainly know there are genetic traits which are passed on to offspring - they can be relatively obvious, like hair colour, eye colour,  etc., or less obvious, e.g. cognitive ability or behaviour. (Often this is because it is also very much influenced by your environment as well - for example your family, friends, and early experiences.) However one major problem is that there are many genetic disorders which are also passed on. These can be very challenging, not only on account of the suffering caused for the individual, but also in that it can make things much more complicated if they want to have children themselves.

However, Italian researchers have now come up with a new method to help treat or reverse such diseases!

Gene therapy itself is rather simple in theory. The aim is to replace the dysfunctional gene with the correct version, which will hopefully lead to the correct proteins being made, and the possible reversal of the disorder.
Unfortunately, there are many problems with this: One very simple one being it is incredibly hard to identify which gene is faulty. Since, with a great many genetic diseases there are many different genes which are involved. Moreover, sometimes it's not even that any one gene is faulty, but because they've all come together in a certain way.

The current method for changing the DNA in each cell is by just using an altered virus to act as a vector for the new gene. The new method uses haematopoietic stem cells (HSCs) as well. This was initially prompted by research into treating three children with metachromatic leukodystrophy (MLD), which has a singular faulty gene as its cause, the ARSA gene. The gene encodes information used by lysosomes, a vesicle containing powerful hydrolytic enzymes, used for the digestion of unwanted material in cells. In MLD patients these don't work correctly in nerve cells, so they begin to slowly decline, leading to brain and spinal cord degeneration, and sensory deprivation.
However, the cells are incredibly difficult to insert a correct copy of the gene into, as they have, unsurprisingly, many biological defenses. To overcome these HSCs were used! (Cells normally found in bone marrow.) Benign viruses carrying a working copy of ARSA were then added to such cells taken from each person, and put back into the bloodstream to act as vectors.
These engineered cells corrected defective cells in the nervous system by supplying the normal version of ARSA. Because these were stem cells, they also reproduced to form new blood cells that themselves took on the same supportive roles, which helped fix the problem!

Hopefully many more such advances in gene therapy will mean that lots more genetic disorders will be able to be treated.

Source: Gene therapy using stem cells prevents inherited diseases: from the Conversation.