Today we celebrate International Albinism Day. On this occasion, DBGen interviews Lluís Montoliu, an internationally renowned scientist for his long research career and his relevant contributions to the knowledge of the genetic and molecular basis of albinism. In addition, he is a renowned specialist in gene editing, the generation of animal models of rare diseases, and a highly recognized science communicator.
Lluís Montoliu holds a degree and a doctorate in Biology from the University of Barcelona. He is currently Deputy Director of the National Biotechnology Center, President of the European Society for Pigment Cell Research (ESPCR), President of the Association for Responsible Research and Innovation in Genetic Editing (ARRIGE), Coordinator of the Scientific Advisory Committee of the Global Alliance of Albinism (GAA), Director of the Spanish node of the European Archive of Mutant Mice (EMMA-Infrafrontier) and member of the Management Committee of the Biomedical Research Center Network on Rare Diseases (CIBER-ER).
- El albinismo. Montoliu, Lluís. Ed. Catarata y Ed. CSIC (2019), ISBN: 978-84-9097-
704-0
- Editando genes: recorta, pega y colorea. Montoliu, Lluís. Ed. Next Door
Publishers (3ª edición, 2021), ISBN:978-8412068597
- Genes de colores. Montoliu, Lluís; Romero, Jesús Ed. Next Door Publishers
(2022), ISBN: 978-84-124894-2-2
Your latest book, Genes de Colores (Color Genes), focuses on the study of pigmentation in humans and animals. The book describes many genes involved in pigmentation, how many of them are associated with rare diseases, such as albinism?
We could say and even remark that a considerable number of the genes causing rare diseases do not generally associate with severe disorders, although there are few exceptions. Beyond the 22 genes causing the 22 known types of albinism, we could include the three types of Griscelli’s syndrome, different types of dyschromatosis, Menkes’ disease, Bloom’s syndrome, some types of Fanconi’s anemia, different types of Waardenburg syndrome, piebaldism, vitiligo, type 1 neurofibromatosis, etc…. You can find the complete list of color genes and associated rare diseases on this website that we update regularly: https://www.ifpcs.org/colorgenes/
In people affected with albinism, why is it important to have a genetic diagnosis?
For several reasons, all of them relevant. First, to increase our knowledge of this genetic condition that, despite being caused by mutations in various genes, it shows common symptoms and deficits that we still do not fully understand, and whose appearance and severity seem related to the mutated gene and the specific mutation. Second, to anticipate any upcoming therapeutic approach. We now know that therapeutic approaches will not be universal but specific to the mutated gene. Therefore, if we want to guide the patient towards therapy we have to identify the gene to be targeted. Third, and this is very relevant point, to discover as soon as possible mutations in genes that cause syndromic albinism, such as the Hermansky-
Pudlak syndrome (HPS) and the Chediak-Hegashi syndrome (CHS). Both are very severe disorders that need special care. We know of 11 subtypes of the former, and a few cases of those that can be life-threatening. HPS1 and HPS4 can lead to pulmonary fibrosis and require lung transplant, and CHS may require bone marrow transplant at a very young age. Fourth, for some families, having a genetic diagnosis may allow them, if they wish, to decide on the course of future pregnancies. Finally, I would add (and this is true for all rare diseases) that for families and affected people, knowing the conclusive genetic diagnosis of their albinism is a small triumph, an inner satisfaction that produces some relief, and a first step to secure the clinical diagnosis and raise hopes for therapy.
Nowadays, what are the approved therapies for the vision loss associated with
albinism?
There are currently no approved therapies for the visual deficit caused by albinism. However, some clinical trials, not yet conclusive, have been conducted with L-DOPA or Nitisinone, two chemical compounds approved for other diseases that have been proposed to treat albinism. L-DOPA is an intermediate in melanin synthesis that also plays an important role in retinal development. Nitisinone blocks the breakdown of the amino acid L-tyrosine (from which melanin is made). In the cases of albinism associated with residual enzymatic activity, Nitisinone may increase melanin production. In addition, gene therapy with viral vectors has been addressed to replace the mutated gene and rescue the function of the normal copy in animal models of
ocular albinism (OA1) and oculocutaneous albinism type 1 (OCA1). They have not yet been approved for clinical trials.
How do you value gene editing, CRISPR, for the development of therapies for albinism?
The CRISPR genetic editing tools, whose use just started in early 2013, are now in clinical phases to treat multiple genetic-based diseases. Their use will probably not be, as was anticipated, to correct mutations based on wild type DNA template sequences. Instead, CRISPR tools are being devised to block or inactivate target genes to achieve therapeutic benefits.
The field is evolving very fast. Currently, several CRISPR versions with much more interesting therapeutic potential than the first generation of genetic editing tools are being used. Not only they are more effective but they also minimize uncertainty issues. I am referring specifically to base editors, tools that allow to replace directly the wrong letters in the DNA with the correct ones. My view is that they will bring us a lot of benefits in the upcoming years. In our CNB laboratory we are trying to validate some of these CRISPR therapeutic approaches to treat albinism animal models that we have generated.