Spinal muscular atrophy due to double gene conversion event

Is Tunisia ready for precision medicine? Challenges of medical genomics within a LMIC healthcare system

As one of the key tools on the precision medicine workbench, high-throughput genetic testing has enormous promise for improving healthcare outcomes. Tunisia has made tremendous progress in acquiring and implementing the technology in the clinical context. However, current utilization does not ensure the whole range of benefits that high-throughput genomic testing provides which impedes the country's ability to move forward into the new era of precision medicine. This issue is primarily related to the current state of Tunisia's healthcare ecosystem and the sociological attributes of its population, creating numerous challenges that must be addressed. In the current review, we aimed to identify and highlight these challenges that may be prevalent in other low and middle-income countries. Essentially, they fall into three main categories that include the socio-economic landscape in Tunisia, which prevents citizens from engaging in precision medicine activities; the current settings of the healthcare system that lack or miss key components for the successful implementation of precision medicine practices; and the inability of the current infrastructure and resources to handle the various challenges related to genomic data and metadata. We also propose five pillar solutions as a framework for addressing all of these challenges, which could strengthen Tunisia's capability for effective precision medicine implementation in today's clinical environment.

Molecular Factors Involved in Spinal Muscular Atrophy Pathways as Possible Disease-modifying Candidates

Spinal Muscular Atrophy (SMA) is a neuromuscular disorder caused by mutations in the SMN1 gene. Being a monogenic disease, it is characterized by high clinical heterogeneity. Variations in penetrance and severity of symptoms, as well as clinical discrepancies between affected family members can result from modifier genes influence on disease manifestation. SMN2 gene copy number is known to be the main phenotype modifier and there is growing evidence of additional factors contributing to SMA severity. Potential modifiers of spinal muscular atrophy can be found among the wide variety of different factors, such as multiple proteins interacting with SMN or promoting motor neuron survival, epigenetic modifications, transcriptional or splicing factors influencing SMN2 expression. Study of these factors enables to reveal mechanisms underlying SMA pathology and can have pronounced clinical application.

Gene conversion in human genetic disease

Gene conversion is a specific type of homologous recombination that involves the unidirectional transfer of genetic material from a ‘donor’ sequence to a highly homologous ‘acceptor’. We have recently reviewed the molecular mechanisms underlying gene conversion, explored the key part that this process has played in fashioning extant human genes, and performed a meta-analysis of gene-conversion events known to have caused human genetic disease. Here we shall briefly summarize some of the latest developments in the study of pathogenic gene conversion events, including (i) the emerging idea of minimal efficient sequence homology (MESH) for homologous recombination, (ii) the local DNA sequence features that appear to predispose to gene conversion, (iii) a mechanistic comparison of gene conversion and transient hypermutability, and (iv) recently reported examples of pathogenic gene conversion events.