Frequency of SNPs in the ghrl gene associated with Diabetes Mellitus type-2: a preliminary analysis of the implication of genetic variability on gene therapy with CRISPR/Cas

The gene of ghrelin (ghrl) (3p26-p25) is responsible for the synthesis of a hormone involved in the stimulation of appetite and storage of fat in adipose tissue (obestatin), which is why it is associated with obesity, multifactorial degenerative chronic disease, capable of increasing the risk of chronic diseases such as DM2 and cardiovascular diseases. The search for targets for gene therapy remains a challenge, and it has been described that the frequency of single nucleotide polymorphisms (SNPs) in genes susceptible to DM2 as ghrl may compromise the effectiveness of gene editing technologies based on RNA-guides of interference (sgRNAs) in CRISPR/Cas systems. Therefore, we sought to determine the frequency of SNPs in the gene candidate for DM2 ghrl in silico. For the Screening of SNPs the NCBI/GenBank and the databases were used: 1000Genomes Project in phase-3, GnomAD, TOPMED, ALSPAC and TWINSUK, gathering the genotype of >172 700 individuals worldwide. A total of 711 SNPs were found, of which 80% statistically presents the lowest relative allelic frequency (≤0.1%), 13% exhibited a relative frequency of between 10-20% and 7% showed a relative frequency of SNPs [C>T] ≥35%. All the observed allelic frequencies are very high in terms of probabilistic occurrence. Additionally, all SNPs were located in introns. These findings should be taken into account because although introns do not encode proteins, SNPs in introns can affect gene expression, and although most of the changes are silent and have no functional repercussions, the large number of SNPs found suggest that the specificity of genetic therapies based on the design of sgRNAs may be affected because of the evident genetic variability to which they are exposed the targets associated with DM2, deserving more studies to fine-tune the effectiveness of this technology with the interest of being able to promote its application at a clinical level.