Primary Hyperoxaluria Type 1 with Homozygosity for a Double-mutated AGXT Allele in a 2-year-old Child

Effect of the allelic background on the phenotype of primary hyperoxaluria type I

PURPOSE OF REVIEW

Primary hyperoxaluria type 1 (PH1) is an autosomal recessive disorder of hepatic glyoxylate metabolism leading to nephrolithiasis and kidney failure. PH1 is caused by mutations on the AGXT gene encoding alanine:glyoxylate aminotransferase (AGT). The AGXT gene has two haplotypes, the major (Ma) and the minor (mi) alleles. This review summarizes the role of the minor allele on the molecular pathogenesis and the clinical manifestations of PH1.

RECENT FINDINGS

PH1 shows high genetic variability and significant interindividual variability. Although the minor haplotype is not pathogenic on its own, it may be crucial for the pathogenicity of some mutations or amplify the effect of others, thus affecting both symptoms and responsiveness to Vitamin B6, the only pharmacological treatment effective in a selected group of PH1 patients.

SUMMARY

In the last years, new drugs based on RNA-interference are available for patients nonresponsive to Vitamin B6, but no specific biomarkers are available to predict disease course and severity. Therefore, a clinical assessment of PH1 taking into account molecular analysis of the mutations and the allelic background and the possible synergism among polymorphic and pathogenic variants should be encouraged to promote approaches of personalized medicine that improve the management of available resources.

Computational insights into missense mutations in HTT gene causing Huntington's disease and its interactome networks

BACKGROUND

Huntington's disease is a rare neurodegenerative illness of the central nervous system that is inherited in an autosomal dominant pattern. Mutant huntingtin protein is produced as a result of enlargement of CAG repeat in the N-terminal of the polyglutamine tract.

AIM OF THE STUDY

Herein, we aim to investigate the mutations and their effects on the HTT gene and its genetic variants. Additionally, the protein-protein interaction of HTT with other proteins and receptor-ligand interaction with the three-dimensional structure of huntingtin protein were identified.

METHODS

A comprehensive analysis of the HTT interactome and protein-ligand interaction has been carried out to provide a global picture of structure-function analysis of huntingtin protein. Mutations were analyzed and mutation verification tools were used to check the effect of mutation on protein function.

RESULTS

The results showed, mutations in a single gene are not only responsible for causing a particular disease but may also cause other hereditary disorders as well. Moreover, the modification at the nucleotide level also cause the change in the specific amino acid which may disrupt the function of HTT and its interacting proteins contributing in disease pathogenesis. Furthermore, the interaction between MECP2 and BDNF lowers the rate of transcriptional activity. Molecular docking further confirmed the strong interaction between MECP2 and BDNF with highest affinity. Amino acid residues of the HTT protein, involved in the interaction with tetrabenazine were N912, Y890, G2385, and V2320. These findings proved, tetrabenazine as one of the potential therapeutic agent for treatment of Huntington's disease.

CONCLUSION

These results give further insights into the genetics of Huntington's disease for a better understanding of disease models which will be beneficial for the future therapeutic studies.