The researchers published 2-year outcomes for the first three patients in July 2013. Results were described as promising. The Phase I/II clinical trial is complete. No additional patients are being recruited while the data is analyzed and work progresses to improve the manufacturability and repeatability of the technology while expansion to other geographies to increase access is being considered. Recruiting was completed for the 20 patient cohort in April 2015, which includes an expansion in December 2014 to add 6 additional patients. Inclusion criteria are pre-symptomatic late infantiles and both pre- and early-symptomatic juveniles. See details on inclusion criteria and the trial protocol here. The trial was at a single center at the San Raffaele Institute in Milan, Italy. All costs were to be paid by the researchers. This was a 3-year study. In March 2013, the last of the 8 primary trial patients started therapy. The trial had several compassionate access patients and ultimately was expanded to 20 patients
In late 2013 GSK exercised its option for the San Rafaelle gene therapy technology and is working with the Milan Investigators to prepare for the next phase of study. Intracerebral Gene therapy – A Phase I/II Clinical Trial started recruiting in Paris in late March, 2013 for an Intracerebral Gene Therapy clinical trial where special "vectors" carrying genetically modified material are directly injected into a dozen sites in the brain. The hope is that the corrected cells and the enzyme they produce will then diffuse into surrounding areas of the brain.
The inheritance probabilities per birth are as follows:
If both parents are carriers:
25% (1 in 4) children will have the disease
50% (2 in 4) children will be carriers, but unaffected
25% (1 in 4) children will be free of MLD – unaffected child that is not a carrier
If one parent is affected and one is free of MLD:
0% (0) children will have the disorder – only one parent is affected, other parent always gives normal gene
100% (4 in 4) children will be carriers (but unaffected)
If one parent is a carrier and the other is free of MLD:
50% (2 in 4) children will be carriers (but unaffected)
50% (2 in 4) children will be free of MLD – unaffected child that is not a carrierIn addition to these frequencies there is a pseudo-deficiency that affects 7–15% of the population. People with the pseudo deficiency do not have any MLD problems unless they also have affected status. With the current diagnostic tests, Pseudo-deficiency reports as low enzyme levels but sulfatide is processed normally so MLD symptoms do not exist. This phenomenon wreaks havoc with traditional approaches to Newborn Screening so new screening methods are being developed. Diagnosis
Clinical examination and MRI are often the first steps in an MLD diagnosis. MRI can be indicative of MLD but is not adequate as a confirming test. An ARSA-A enzyme level blood test with a confirming urinary sulfatide test is the best biochemical test for MLD. The confirming urinary sulfatide is important to distinguish between MLD and pseudo-MLD blood results.