A novel 5 nucleotide deletion in XPA gene is associated with severe neurological abnormalities

Revisiting the structural features of the xeroderma pigmentosum proteins: Focus on mutations and knowledge gaps

The nucleotide excision repair pathway is a broadly studied DNA repair mechanism because impairments of its key players, the xeroderma pigmentosum proteins (XPA to XPG), are associated with multiple hereditary diseases. Due to the massive number of novel mutations reported for these proteins and new structural data published every year, proper categorization and discussion of relevant observations is needed to organize this extensive inflow of knowledge. This review aims to revisit the structural data of all XP proteins while updating it with the information developed in of the past six years. Discussions and interpretations of mutation outcomes, mechanisms of action, and knowledge gaps regarding their structures are provided, as well as new perspectives based on recent research.

Genetic investigation of XPA gene: high frequency of the c.682C>T mutation in Moroccan XP patients with moderate clinical profile

OBJECTIVE

Xeroderma pigmentosum (XP) is a genetically and clinically heterogeneous disease, associated with an inherited defect in one of eight different genes (XPA to XPG and XPV). In addition to the early onset of the skin manifestations, the XP group A is marked by the presence of a mild to severe neural disorders which appear tardily and worsens with age. In this study, 9 patients with moderate clinical profile belonging to 6 XP families were recruited to determine the XPA mutational spectrum in Morocco, using the direct sequencing of the whole coding region of the XPA gene.

RESULTS

The genetic investigation of the XPA gene showed that 7 from 9 patients were homozygous for the c.682C>T, p.Arg228X mutation, while all their investigated family members were heterozygous. The frequency of this mutation was estimated to be 83.33% (5/6 families) .The molecular analysis of the 5 other exons of the XPA gene, showed that the 2 negative siblings carried no mutation in the XPA gene. This finding suggests that c.682C>T (p.Arg228X) mutation is relatively associated with moderate phenotype in XP group A Moroccan families; this result will also contribute to improve the molecular diagnosis of XP disease in Moroccan patients.

XPA: A key scaffold for human nucleotide excision repair

Nucleotide excision repair (NER) is essential for removing many types of DNA lesions from the genome, yet the mechanisms of NER in humans remain poorly understood. This review summarizes our current understanding of the structure, biochemistry, interaction partners, mechanisms, and disease-associated mutations of one of the critical NER proteins, XPA.