Novel mutation identified in the DDB2 gene in patients with xeroderma pigmentosum group-E

The Evaluation of the Genetic Variation Types of the Uridine Diphosphate Glucuronosyl Transferase 1A1 Gene by Next-Generation Sequencing and Their Effects on Bilirubin Levels in Obese Children

Background and Objectives: Obesity is a major nutritional problem with an increasing prevalence among children and adolescents. The uridine-diphosphate-glucuronosyl-transferase1A1 (UGT1A1) gene encodes the UDP-glucuronosyl transferase enzyme, converting the toxic form of bilirubin to a soluble, nontoxic form. There are yet to be studies on the evaluation of the UGT1A1 variant types detected by next-generation sequencing (NGS) and their effects on bilirubin levels in nonsyndromic obese children. Methods: Forty-five children with body mass index (BMI) >95 percentile (p) constituted the obesity group and fourteen healthy children with BMI <85p constituted the control group. Anthropometric, clinical features, and biochemical parameters were evaluated. Furthermore, the UGT1A1 gene was sequenced by NGS. Results: The obese patients had lower total, direct, and indirect bilirubin levels (p = 0.422, 0.026, and 0.568, respectively). In addition, obese patients had more genetic variations in the UGT1A1 gene compared with the control group (62.2% and 50%, respectively). We found that children with variations had higher total direct and indirect bilirubin levels compared with those without variation (p = 0.016, 0.028, and 0.015, respectively). Children diagnosed with obesity in the first two years of their life had fewer genetic variations and lower total bilirubin levels (p = 0.000 and 0.013, respectively). Conclusions: It is assumed that bilirubin can be protective against many chronic diseases. Although bilirubin levels are found to be lower in obese children compared with the control group, some variations in the UGT1A1 gene may be supported by raising bilirubin. We suggest that high bilirubin levels caused by those UGT1A1 variations may be protective against obesity and its many negative effects.

Apoptosis-associated speck-like protein containing a CARD (ASC), TNF Like Factor 1a(TL-1a) and B Cell Chemoattractant Chemokine Ligand 13(CXCL-13) expression profiles in familial Mediterranean fever (FMF) patients

Objectives: This study was carried out to compare the expression levels of ASC(Apoptosis Associated Speck Like Protein Containing a CARD), TL-1a(TNF Like Factor 1a) and CXCL 13(B Cell Chemoattractant Chemokine Ligand 13) genes in FMF patients According to Tell-Hashomer Criteria and Genetic analysis result in Düzce University Research and Application Hospital with healthy controls and to determine their clinical significance in FMF. Method: 36 patients (20 girls, 16 boys) and 12 healthy controls (7 girls, 5 boys) were included in the study. RNA was isolated from the peripheral blood of each individual and expression levels of ASC, TL-1a and CXCL 13 genes were determined. Routine biochemical parameters were also determined. Result: CXCL 13 and TL-1a gene expression levels were significantly increased in patients with FMF, the expression level of the ASC gene was found to be increased in FMF patients, but not significantly. Conclusion: The expression levels of these genes may be related to the pathogenesis of the disease and these genes could be used as a marker in the early diagnosis of the disease.

A protein with broad functions: damage-specific DNA-binding protein 2

Damage-specific DNA-binding protein 2 (DDB2) was initially identified as a component of the damage-specific DNA-binding heterodimeric complex, which cooperates with other proteins to repair UV-induced DNA damage. DDB2 is involved in the occurrence and development of cancer by affecting nucleotide excision repair (NER), cell apoptosis, and premature senescence. DDB2 also affects the sensitivity of cancer cells to radiotherapy and chemotherapy. In addition, a recent study found that DDB2 is a pathogenic gene for hepatitis and encephalitis. In recent years, there have been few relevant literature reports on DDB2, so there is still room for further research about it. In this paper, the molecular mechanisms of different biological processes involving DDB2 are reviewed in detail to provide theoretical support for research on drugs that can target DDB2.

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.

Case Report: Identification of Novel Variants in ERCC4 and DDB2 Genes in Two Tunisian Patients With Atypical Xeroderma Pigmentosum Phenotype

Xeroderma Pigmentosum (XP) is a rare genetic disorder affecting the nucleotide excision repair system (NER). It is characterized by an extreme sensitivity to sunlight that induces cutaneous disorders such as severe sunburn, freckling and cancers. In Tunisia, six complementation groups have been already identified. However, the genetic etiology remains unknown for several patients. In this study, we investigated clinical characteristics and genetic defects in two families with atypical phenotypes originating from the central region in Tunisia. Clinical investigation revealed mild cutaneous features in two patients who develop multiple skin cancers at later ages, with no neurological disorders. Targeted gene sequencing revealed that they carried novel variants. A homozygous variation in the ERCC4 gene c.1762G>T, p.V588F, detected in patient XP21. As for patient XP134, he carried two homozygous mutations in the DDB2 gene c.613T>C, p.C205R and c.618C>A, p.S206R. Structural modeling of the protein predicted the identified ERCC4 variant to mildly affect protein stability without affecting its functional domains. As for the case of DDB2 double mutant, the second variation seems to cause a mild effect on the protein structure unlike the first variation which does not seem to have an effect on it. This study contributes to further characterize the mutation spectrum of XP in Tunisian families. Targeted gene sequencing accelerated the identification of rare unexpected genetic defects for diagnostic testing and genetic counseling.